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In this study, extrusion experiments were carried out on Al-Mg-Si-Cu-Mn alloys with different extrusion ratios (ERs), extrusion temperatures (ETs), and extrusion speeds (ESs). By using electron backscatter diffraction (EBSD) analysis, tensile testing, and other analytical means, the evolution of microstructure, texture, and properties of the extruded alloys was systematically investigated, and the strengthening-toughening mechanism induced by the extrusion parameters was revealed. It was found that the strength of the extruded alloy shows a tendency to first increase and then decrease with the increase of the ER and ES, and the 'critical ER' and 'critical ES' are 29.5 and 2.5 mm/s, respectively; the strength of the extruded alloy gradually increases with the increase of the ET. The alloy achieved excellent strength-toughness matching at the ER of 29.5, ET of 480 °C, and ES of 2.5 mm/s. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the extruded alloy at this condition were ∼169.58 MPa, ∼314.36 MPa, and ∼16.57 %, respectively. This excellent strength-toughness matching is mainly related to the following aspects: 1) grain refinement provides high grain boundary strengthening effect and appropriate work hardening ability; 2) <111>//ED texture has a strong preferential orientation; 3) the variation trend of dislocation density is importantly related to <111>//ED and EX a {011}<111> textures; 4) Cube{001}<100> and Goss{011}<100> textures have a softening effect. The above findings provide new insights into the potential mechanisms of hot extrusion forming of aluminum alloys, which are of important guiding for the design and development of aluminum alloys with excellent strength-toughness combinations. [Display omitted] • <100>//ED texture is related to Cube{001}<100> and Goss{011}<100> textures. • Cube{001}<100> and Goss{011}<100> textures have a softening effect. • <111>//ED texture has a strong preferential orientation. • Dislocation density is importantly linked to <111>//ED and EX a {011}<111> textures. • Excellent strength-toughness matching of Al-Mg-Si-Cu-Mn extrusion alloys can be realized under specific extrusion parameters. [ABSTRACT FROM AUTHOR]

High strength aluminium alloys are of significant interest for laser-based Additive Manufacturing as they can provide a high specific strength but have limited assembly possibilities due to poor weldability and the presence of large intermetallic particles challenging the conventional manufacturing route. Increasing the geometrical freedom by enabling their use with laser-based Additive Manufacturing would create new possibilities. This study investigates the possibilities of using an aluminium 7000 series alloy with Laser Powder Bed Fusion (L-PBF) and secondly for comparison with Direct Energy Deposition (DED). The chemical composition targets 5.1–6.1 wt% Zn and 2.1–3.9 wt% Mg. The level of Zn and Mg in the powder was increased to 10 wt% Zn and 3 wt% Mg to compensate for the expected evaporation during the laser-based AM process and guarantee a sufficient Zn and Mg content for precipitation strengthening. Solidification cracking in the initial alloy composition was resolved by the addition of 1 wt% Zr and 1 wt% V. For L-PBF, a study of the impact of the laser spot size showed a larger spot size is beneficial to improve the process stability. A study of the capability of preheating and of slowing down the process showed both further improve the process stability as well which is required to manufacture successfully larger parts to characterise the quasi-static tensile properties. For optimal process parameters for a fast process, meaning a scan speed of 700 mm/s, a yield stress of 425 ± 7 MPa and an ultimate tensile strength of 442 ± 5 MPa was obtained after a homogenisation and ageing heat treatment. In the as built state, the strength was significantly lower. For optimal process parameters for a slow process, meaning a scan speed of 250 mm/s, a yield stress of 398 ± 11 MPa and an ultimate tensile strength of 440 ± 16 MPa were obtained in as built state. For DED the mechanical properties of the alloy showed to be significantly dependent on process parameters. An excessive energy input results in more Zn and Mg evaporation and decreased cooling rates. Such parameters also impact the process stability of DED throughout the build cycle. Limiting the energy input resulted in dense samples and stable build cycles which after a heat treatment to peak ageing reached a yield stress of around 400 MPa and an ultimate tensile stress of around 440 MPa in the X- and Z-direction. • L-PBF of Al-10Zn-3Mg-1Zr-1V achieves a high relative material density. • High yield stress (398 MPa) and ultimate tensile stress (440 MPa) in as built state. • Occurrence of solidification cracking is linked to L-PBF process parameters. • DED combined with a heat treatment leads to comparable strengths. [ABSTRACT FROM AUTHOR]

Friction Stir Extrusion (FSE) has been proven as an effective solid-state process to directly recycle metal chips into high-quality wires/rods/tubes. However, the demand for Al-based composite wires with enhanced properties is substantial, and achieving a uniform distribution of the strengthening phase within the composite wire by establishing a robust metal/ceramic interface remains a significant challenge. In this study, AA6082 Aluminum alloy wires reinforced with 12.5 vol% SiC particles, exhibiting homogeneous particle distribution and superior mechanical properties, were successfully produced through the FSE technique. The investigation focused on examining the influence of processing parameters and the addition of SiC reinforcement on the microstructure and mechanical characteristics of the extruded wires. Scanning electron microscopy (SEM), Electron Backscatter Diffraction (EBSD), together with microhardness, bending, and tensile tests, were used to comprehensively analyze the resulting properties. The findings demonstrate a substantial enhancement in the wires' mechanical properties due to the SiC particles. Both tool rotation and tool force were varied during the experimental campaign. Notably, the reduction in porosity and grain refinement resulted in a 12.78 % increase in tensile strength and an 18.6 % improvement in microhardness compared to Al 6082 alloy extruded wires. Grain orientation analysis revealed a fully recrystallized microstructure with a weak texture. Furthermore, the study evaluated power consumption and surface roughness while assessing the feasibility of deposition, thereby highlighting the potential application of this technique in advanced additive manufacturing processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Al-Ce alloys have attracted recent interest because of their high thermal stability due to the low solubility of Ce in the Al matrix. The Al 11 Ce 3 eutectic phase gives excellent strain hardening behavior and moderate high-temperature strength in the as-cast state. However, its strengthening effect is limited by its coarse as-cast structure. Therefore, alternative manufacturing methods such as additive manufacturing or equal channel angular pressing have been applied to refine the Al 11 Ce 3 phase to good effect. However, these techniques are both expensive and time-consuming. Therefore, this study aims to use Shear Assisted Processing and Extrusion (ShAPE), an emerging solid phase processing technique that is more easily scalable than the previously mentioned methods. ShAPE can produce useful cross-sections of an Al-8Ce-4Mg alloy while refining the Al 11 Ce 3 phase to produce a higher strength material. It was found that a low temperature ShAPE process can improve the room temperature yield strength by ∼60 % compared to a binary Al-4Mg alloy. Additionally, the high-temperature yield strength of the Al-Ce alloys increased by 20 %, with a simultaneous 15 % improvement in ductility compared to the binary Al-Mg alloy. These results highlight the potential for ShAPE as a processing technique for Al-Ce alloys. • Shear Assisted Processing and Extrusion is suitable for processing an Al-8wt%Ce-4wt%Mg alloy into a round tube. • Processing refined the Al 11 Ce 3 particles, which increased the UTS of the alloy by 366 % compared to an Al-4wt%Mg alloy. • Reducing processing temperature increased strength and increasing extrusion speeds increased ductility. [ABSTRACT FROM AUTHOR]

Experiments were conducted to systematically assess the superplastic properties and the microstructural changes of an Al-3Mg-0.2Sc alloy processed by 10 HPT revolutions at room temperature (RT ≈ 300 K) or at 450 K after subsequent tensile testing at temperatures from 473 to 723 K over a wide range of strain rates. The HPT processing at RT led to the development of elongated grains with an average size of ∼140 nm whereas the grain structures were equiaxed and slightly larger (∼150 nm) after HPT at 450 K. After HPT processing at RT, the Al-Mg-Sc alloy exhibited true superplastic flow at low homologous temperatures and attained a maximum elongation of ∼850 % at 523 K. Nevertheless, the elongations decreased at temperatures T ≥ 623 K and an elongation higher than 400 % was only achieved at 673 K for a strain rate of ε ˙ = 4.5 × 10−3 s−1. The material processed by HPT at 450 K displayed superior microstructural stability and substantially higher superplastic ductilities. Elongations of >1100 % were attained at 673 K for strain rates from 3.3 × 10−4 to 1.0 × 10−1 s−1 and a record elongation of ∼1880 % for an HPT-processed metal was achieved at 1.5 × 10−2 s−1 at 673 K. High strain rate superplasticity was also reached for an extended range of temperatures and strain rates. Analysis of the data confirms a stress exponent of ∼2 which is consistent with superplastic flow by grain boundary sliding accommodated by dislocation glide and climb. [ABSTRACT FROM AUTHOR]

This study investigates the compressive creep response of hypo- and near-eutectic Al-Ce alloys via finite-element modeling (FEM), by considering the composite response of a weak, fast-creeping Al matrix containing slow-creeping Al 11 Ce 3 eutectic reinforcement. In the as-cast microstructure of an eutectic Al-12.5 wt%Ce alloy, the Al 11 Ce 3 eutectic phase is lamellar, regardless of the various cross-sectional geometries (Chinese-script, fish-bone, and comb-like). FEM models based on these various lamellar microstructures investigate the effect of Al 11 Ce 3 reinforcement volume fraction, orientation, and geometry on load transfer performance between matrix and reinforcement during creep deformation. FEM predicts that, when the lamellar Al 11 Ce 3 phase is continuous along the loading direction (where load transfer is most effective), the creep resistance of the alloy is barely affected by cross-sectional geometry of the Al 11 Ce 3 reinforcement or by the solid-solution strengthening of the Al matrix, at constant Al 11 Ce 3 volume fraction. However, alloy creep resistance and load transfer between phases are significantly reduced when applying load parallel to aligned, discontinuous lamellae, and they can be improved by matrix solid-solution strengthening. Furthermore, Al 11 Ce 3 short plates (as created in Al-12.5Ce by coarsening of lamellae upon over-aging at 590 °C/24 h) provide the least creep resistance and load transfer. Lastly, multi-colony FEM models are created by combining colonies with various lamellar orientations to approximate the creep performance of polycrystalline hypo- and near-eutectic alloys which, when compared to experimental data for hypoeutectic Al-7Ce and for near-eutectic Al-(10–13)Ce, provide better predictions than single-colony FEM models or analytical solutions. [ABSTRACT FROM AUTHOR]

A 6061 Al alloy build consisting of 3 additive layers was successfully fabricated using a sheet-based friction stir additive manufacturing process. The study focused on analyzing the microstructure and texture characteristics in the central regions of each layer and the thermal mechanical affected zones (TMAZs) beneath the stir zones (SZs). Mechanical properties of the final multilayered build were also analyzed. The results revealed that, following plastic deformations and thermal cycles, the equiaxed grains formed in the central region of layer 2 were the finest (∼7.9 μm) among the three layers, attributed to the highest degree of recrystallization. Additionally, the average grain size of the TMAZs further decreased to ∼4.0 μm due to lower frictional heat generated by the tool pin. Furthermore, the geometrically necessary dislocation densities of the TMAZs showed a slight increase compared to those of the central regions. In terms of textures, shear and deformation textures were predominant in the central regions, while shear texture dominated the TMAZs. The primary precipitates found at the center of the SZs included β, β′, Q′, Al 8 Fe 2 Si and (Fe,Mn,Cr) 3 SiAl 12. Besides, the yield strength and ultimate tensile strength of the build drop significantly to 119.7 MPa and 204.6 MPa, respectively. Moreover, a non-monotonic decrease in hardness as the increase of distance from the top of build could be found, due to the existence of numerous grains with soft orientations and the intense dissolution and coarsening of β" and β' phases. [ABSTRACT FROM AUTHOR]

Hot tensile tests were performed to assess the temperature and strain rate dependency of the yield strength of particle-containing aluminium wrought alloys. In this class of alloys yield strength accrues from a combination of the intrinsic matrix strength of pure Al, the strength due to second-phase particles and the strength due to alloy elements in solid solution. In Mg-containing Al alloys dynamic strain ageing (DSA) adds an extra strength contribution in a certain range of temperatures and strain rates. For each of these mechanisms a suitable constitutive model was devised; the resultant yield strength predictions were compared to the experimental results of various particle-containing Al sheet alloys. For non-heat-treatable Al alloys where the effect of sub-micron sized dispersoids is predominant, the model is capable of predicting the experimental yield strength with good accuracy, including the general decrease of yield strength with increasing temperature and a rather mild strain rate sensitivity. In Mg-containing alloys the incorporation of DSA was decisive to yield adequate model predictions, especially in an intermediate temperature range where DSA is most pronounced. It is only at very high temperatures and/or low strain rates that the presumed activation of additional rate-sensitive deformation mechanisms led to a significant softening of the Mg-bearing alloys which is not covered by the present modelling approach. [ABSTRACT FROM AUTHOR]

Modern aerospace and transportation sectors have imposed more stringent requirements for high-strength aluminum alloys. Taking into account factors such as processing, assembly, maintenance, and recycling, there is a desire to develop one high strength aluminum alloy over wide temperature range from 25 °C to 300 °C, however, it is an ongoing challenge topic. Here, a novel Al-Cu-Li-Sc alloy with a reduced Cu content (∼2.8 wt%) was designed, exhibiting great yield strength with 482 MPa at 25 °C, 351 MPa at 200 °C, and 186 MPa at 300 °C, better than present commercial Al-Cu-Li alloys, Al-Cu-Sc alloys, due to the promotion of nucleation of T1 precipitates and their improved coarsening resistance. The novel Al-Cu-Li-Sc also overcomes the shortcoming of commercial Al-Cu-Li alloy which is the rapid degradation of mechanical properties after thermal exposure at 200 °C, as well as exhibiting comparable heat resistance to Al-Cu-Sc alloy after thermal exposure at 300 °C. This study offers a valuable engineering insight to develop light-weight, high-strength and heat-resistant aluminum alloys. [ABSTRACT FROM AUTHOR]

With rapid development of aerospace and automobile, the service condition of structural components becomes increasingly harsh, diverse and high mechanical properties are urgently needed. In this work, an advanced in-situ ZrB 2np /AA6111 composite with excellent room and high-temperature properties was prepared via Al-Zr-B reaction system. The microstructure revealed that ZrB 2 nanoparticles with regular polygonal shapes ranged from 10 to 150 nm approximately, and a good α-Al/ZrB 2 interface bonding was confirmed. The agglomeration of ZrB 2 particles was significantly weakened during hot extrusion. Due to the inhibiting effect on dislocation motion and pinning effect on grain boundaries induced by ZrB 2 particles, fine recrystallized grains were obtained in ZrB 2 /AA6111 composites after extrusion. Compared with AA6111 matrix alloy, the yield strength, ultimate tensile strength and elongation of AA6111-3ZrB 2 composites at room temperature and 300 °C were increased by 18.9 %, 12.7 %, 50.0 % and 34.1 %, 22.4 %, 42.4 %, respectively. An excellent room and high-temperature strengthening effect was simultaneously achieved assisted by ZrB 2 particles. The improvement of room-temperature properties was mainly owed to the Grain refinement and Orowan bypassing strengthening mechanisms. The good high-temperature properties mainly relied on the superior coarsening resistance of ZrB 2 particles which could fully played the Orowan strengthening effect and well protected the grain boundaries at high temperature. This work provides a feasible approach to design high-performance aluminum alloys and is beneficial for the further development of modern industries. • Room and high temperature properties of AA6111 were improved by ZrB 2 particles. • In-situ ZrB 2 particles showed excellent thermal stability at high temperature. • The DRX was significantly promoted by ZrB 2 particles during hot extrusion. [ABSTRACT FROM AUTHOR]

The effects of hot deformation strain rates and temperatures on aluminium alloys' dynamic recovery and recrystallisation mechanisms have been widely discussed in the literature. However, their influence remains controversial due to a need for comprehensive and detailed thermomechanical testing and characterisation data across a wide range of hot deformation conditions. In this study, hot compression tests of AA7050 were conducted at strain rates of 0.0005–5 s−1 and temperatures of 380–460 °C. The geometrically necessary dislocation (GND), low-angle grain boundary (LAGB) and high-angle grain boundary (HAGB) were acquired by the latest high angular resolution, high-speed EBSD detector (OI Symmetry 2), and their underlying mechanisms were analysed in relation to Zener-Hollomon parameter (Z). It was found that within the tested range of the hot compression condition (ln (Z) between 20.23 and 29.45), continuous dynamic recrystallisation (CDRX) predominates at lower ln (Z) values with its activity being initially increased and then decreased as ln (Z) rises, while discontinuous dynamic recrystallisation (DDRX) becomes dominant at higher ln (Z) levels. This transition of the dominant mechanism is intriguingly reflected in the evolution of HAGB length, which increases, then decreases and finally increases again. The LAGB length shows a relatively linear relationship with ln (Z), and the average GND density exhibits a near-linear correlation until reaching a plateau. Based on the obtained results, the transformation of the dominant microstructural evolution mechanisms with increasing ln (Z) was clarified: from grain growth, to recovery, to CDRX, and then to DDRX, along with the quantitative trend of HAGB length per unit area. This transformation mechanism is believed to encompass the full range of material processing window, providing a basis for justifying the previous controversial proposition in literature and a guide for defining and fabricating microstructures in manufacturing applications. [ABSTRACT FROM AUTHOR]

The 2195 aluminum alloy is limited in aerospace structural components due to its poor formability at room temperature (RT) and narrow range of working parameters at hot deformation, which prompted considerable interest in understanding the microscopic damage mechanisms at different temperatures. This work focuses on the interaction between the second-phase particles and the matrix, as well as their evolving relationship to investigate the damage mechanisms of the 2195-O alloy. Particular attention was given to the nucleation mechanisms that trigger damage. SEM, BSE, and EBSD methods were employed to characterize the evolution of the microstructure during tensile tests ranging from RT to 450 °C. The results indicate that nucleation mechanisms exhibit temperature-dependent variations: At RT, a high area fraction of particles and inadequate coordination with matrix deformation lead to stress concentration on the particles, and particle fracture is the primary nucleation mechanism. Meanwhile, voids nucleate at the particle-matrix interface at 300–450 °C, where localized strain concentration is induced by differential deformation between particles and the matrix. Moreover, matrix cracking occurs at 450 °C due to a reduction in the quantity of particles and grain coarsening. Matrix-cracks tend to expand and aggregate, leading to decreased elongation at 450 °C. [ABSTRACT FROM AUTHOR]

To improve the ductility of ultrafine-grained Al alloys, a simple and effective approach was developed to incorporate low-density ZrB 2 nanoparticles and high-density S′ precipitates into the 2024Al matrix through submerged FSP and subsequent aging. The resultant nanocomposite exhibits significant work-hardening, thereby achieving superior strength-ductility synergy during uniaxial tensile tests at room temperature. [ABSTRACT FROM AUTHOR]

The effect of age hardening treatment on microstructure, tensile properties, and corrosion behavior of additively manufactured A20X alloy was investigated. Three single-step aging temperatures (150 °C, 175 °C, and 200 °C) and one double-step aging temperature (pre-aging at 165 °C followed by aging at 185 °C) along with varying heat treatment durations ranging from 30 min to 144 h, were studied systematically. Microstructural characterizations revealed that the co-existence of coherent/semi-coherent (Ω, θ ′) and incoherent precipitates (θ) resulted in the maximum hardening effect (up to 30 % higher microhardness). This improved the yield strength at room and 150 °C by 33.4 % and 22.6 %, respectively. Double aging delivered the best combination of microstructure with fine grains and optimal precipitate assembly in a short duration (12–16 h). The heat-treated LPBF A20X showed higher ductility and similar mechanical properties compared to the cast A20X. However, optimal precipitate characteristics reduced the corrosion potential by 13–16 % due to a higher galvanic reaction. The highest corrosion potential (−0.622 V) was achieved in the solutionized state. [ABSTRACT FROM AUTHOR]

The effect of age hardening treatment on microstructure, tensile properties, and corrosion behavior of additively manufactured A20X alloy was investigated. Three single-step aging temperatures (150 °C, 175 °C, and 200 °C) and one double-step aging temperature (pre-aging at 165 °C followed by aging at 185 °C) along with varying heat treatment durations ranging from 30 min to 144 h, were studied systematically. Microstructural characterizations revealed that the co-existence of coherent/semi-coherent (Ω, θ ′) and incoherent precipitates (θ) resulted in the maximum hardening effect (up to 30 % higher microhardness). This improved the yield strength at room and 150 °C by 33.4 % and 22.6 %, respectively. Double aging delivered the best combination of microstructure with fine grains and optimal precipitate assembly in a short duration (12–16 h). The heat-treated LPBF A20X showed higher ductility and similar mechanical properties compared to the cast A20X. However, optimal precipitate characteristics reduced the corrosion potential by 13–16 % due to a higher galvanic reaction. The highest corrosion potential (−0.622 V) was achieved in the solutionized state. [ABSTRACT FROM AUTHOR]

In this research, 6082 aluminum alloy automotive flange components with complex shape and large wall thickness difference were formed via squeeze casting. The effect of T6 heat treatment process parameters (solution time, solution temperature, aging time and aging temperature) on microstructure and mechanical properties were studied through controlling variable method. The yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of 6082 aluminum alloy automotive flange components after T6 heat treatment were firstly increased and then decreased with the increasing solution temperature, solution time and aging time, respectively. However, with an increase of aging temperature, YS and UTS were significantly increased, while EL was decreased. The optimal T6 heat treatment process parameters (solution temperature of 525 °C, solution time of 180 min, aging temperature of 185 °C and aging time of 420 min) were obtained. Under the optimal T6 heat treatment process parameters, the YS, UTS, EL were 304.2 MPa, 348.7 MPa and 7.42 %, respectively. The fracture mode is a mixture of ductile and cleavage fracture. After T6 heat treatment, a plethora of tiny precipitates appeared, which included the Al(FeMn)Si phase with a size of about 100 nm and the finer β ″-Mg 2 Si phase. These tiny precipitates lead to lattice distortion to hinder the movement of dislocations and they had a significant strengthening effect on the improvement of mechanical properties. In short, 6082 aluminum alloy automotive flange components produced by squeeze casting after T6 heat treatment has significantly competitive advantages for its outstanding mechanical properties. [ABSTRACT FROM AUTHOR]

To improve the ductility of ultrafine-grained Al alloys, a simple and effective approach was developed to incorporate low-density ZrB 2 nanoparticles and high-density S′ precipitates into the 2024Al matrix through submerged FSP and subsequent aging. The resultant nanocomposite exhibits significant work-hardening, thereby achieving superior strength-ductility synergy during uniaxial tensile tests at room temperature. [ABSTRACT FROM AUTHOR]

The electrical-assisted tensile tests of 5086 Al alloy sheets with different current parameters were carried out at room temperature with a frequency of 150 Hz and voltages of 50 V, 60 V and 70 V. It was found that the serrated plastic instability (named PLC effect) was eliminated as the pulse current increased to 150 Hz/60 V, but the PLC effect was observed with 150 Hz/50 V. To distinguish the thermal effect and athermal effects of pulse current on PLC effect, the comparative heating tensile (HT) test in furnace with a temperature rising trend of 150 Hz/60 V was conducted. The obtained curves still showed serrated flow behavior, indicating that the thermal effect was insufficient to suppress the PLC effect. The influence of pulse current on the microstructure and texture evolution was investigated through TEM and EBSD. According to the microscopic analysis, the pulse current accelerated the solute atoms' diffusion and dislocation movement. S orientation {123}<634> of 150 Hz/60 V presented more obvious transformation compared with that of HT specimen. It was illustrated that the athermal effect of pulse current plays an important role in the crystal orientation and suppressing the PLC effect. [ABSTRACT FROM AUTHOR]

We have assessed the elasto-plastic (sub)surface behaviour of 7050-T7451 aluminium alloy treated by shot peening using S110 steel shots of 300 μm in diameter and two different intensities, namely Almen intensity (A) of 3.4 (low-intensity) and 10.9 (high-intensity). Shot peening (SP) is a cold work process applied in the aerospace industry to enhance the fatigue tolerance of structural components after machining. The local mechanical response within the SP-induced layer was depth profiled at room temperature by performing an X-ray micro-diffraction experiment in transmission geometry at a synchrotron source, during tensile loading of the specimen to rupture. The presence of a SP-induced layer in the specimen is evidenced by compressive longitudinal lattice strains (∼-540 με for low-intensity and ∼-4200 με for high-intensity at 0.1 mm from the surface for the 311 reflection), parallel with respect to the applied load, i.e. perpendicular to the direction of impact of the steel shots, and also by higher values of the Full-Width-at-Half-Maximum (FWHM) of the diffraction peaks than those measured in the bulk material, due to the local plastic deformation induced by shot peening. High-intensity shot peening produced a higher surface roughness (Sa ∼13 μm), and also two times thicker deformed surface layer (∼0.4 mm), than low-intensity shot peening (Sa ∼2 μm and ∼0.2 mm thick deformed layer). For both shot peening conditions, the local yield stress of the surface layer and bulk material were similar, however the severely affected layers exhibit a non-linear elastic behaviour when applying loads lower than the yield stress of the material. Beyond yielding, the presence of SP-induced layers is mainly evidenced by the relatively higher value of the FWHM near-surface compared to the bulk (∼20 % higher for low-intensity and ∼40 % for high-intensity), due to the initial plastic deformation accumulated during shot peening and additional plasticity during loading of the specimen. • Surfaces treated with low- and high-intensity shot peening (SP) were depth profiled. • In-situ tensile tests combined with X-ray micro-diffraction were done to rupture. • High-intensity SP induced a thicker compressive layer than low intensity SP. • The yield stress of both surfaces is similar to the bulk material. • SP affected layers show a non-linear elastic behaviour when applying elastic loads. [ABSTRACT FROM AUTHOR]

The predominant method for improving the mechanical characteristics of aluminum-lithium (Al–Li) alloys during laser welding is by regulating the transition from columnar crystals to equiaxed crystals. The transition is facilitated through the incorporation of TiC particles, which play a crucial role in augmenting the strength and toughness of the aluminum alloy. The inclusion of TiC particles offers a new opportunity to enhance the utilization of Al–Li alloys in laser welding procedures. The main aim of this study is to control the transition from columnar to equiaxed crystal structures by creating a TiC nanoparticle-reinforced aluminum alloy filler wire. This is intended to improve the properties of laser-welded joints. The study investigates the impact of different TiC particle contents on the microstructural characteristics. The presence of TiC particles is noted to enhance the transformation of columnar crystals into equiaxed crystals in the welded joints, resulting in a refined microstructure. The augmentation of particle content results in a notable reduction in the average grain size, decreasing from 78.25 μm to 37.15 μm. This alteration shifts the directional growth preference from specific crystallographic axes to a stochastic trajectory. Significantly, when the particle content reaches 0.6 wt%, remarkable enhancements in both tensile strength and elongation are evident, resulting in an ultimate tensile strength of 318 MPa and an elongation of 4.8 %. The dispersed configuration of TiC particles plays a pivotal role in hindering the movement of dislocations, consequently increasing the energy necessary for this mechanism. Moreover, the existence of these particles at grain boundaries impedes the propagation of cracks by altering the direction of the crack path, absorbing additional energy, and consequently improving toughness. An evident pattern emerges when examining higher particle concentrations, indicating that a decrease in ultimate tensile strength is concomitant with an increase in elongation. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L-PBF) is an additive manufacturing technology widely applied to the manufacture of metallic parts. The L-PBF processed aluminum-silicon (Al–Si) cast-type alloy components exhibit an anisotropic tensile ductility. In this study, we investigated the influence of heat treatments on the microstructural features of an Al–12%Si binary alloy fabricated via L-PBF and the associated inhomogeneous deformation of its melt-pool structure, which contributes to the resulting anisotropic tensile ductility. The mechanical inhomogeneity of the melt-pool structure and the change induced by annealing at various temperatures (300 and 530 °C) were characterized using microscale digital-image correlation analyses of scanning electron microscopy images obtained in situ during tensile deformation and nanoindentation hardness mapping. In the specimen fabricated via L-PBF, the high strain was concentrated at the locally coarsened microstructure (the soft region) along the boundaries of the melt pools rather than at the refined solidification microstructure (the hard region) within the melt pools. The localized strain varied depending on the geometrical relation between the orientation of the melt-pool boundary and the tensile direction, thus contributing to the anisotropic tensile ductility. This tendency appeared less pronounced in the specimen annealed at 300 °C, which exhibited a slightly homogenized melt-pool structure. The reduced strain localization is associated with a reduced difference in local strength between the melt-pool boundary (soft region) and the melt-pool interior (hard region). The slight homogenization of the melt-pool structure emphasized the effect of grain morphologies in the α-Al matrix on the inhomogeneous deformation within melt pools. In the specimen annealed at 530 °C, which exhibited a homogenized α-Al/Si two-phase microstructure, the uniformly distributed Si phase would be responsible for the homogenous deformation, resulting in an isotropic tensile ductility. This study advances our understanding of the correlation between the melt-pool structure and the deformation behavior of Al–Si alloys processed using L-PBF, which provides new insights for controlling the ductility by post-processing. [Display omitted] • Microstructures of L-PBF Al–12Si alloy after annealing at 300/500 °C were studied. • Nanoindentation revealed that melt-pool boundary was locally softer than interior. • Micro-DIC analysis captured inhomogeneous deformation on the melt-pool structure. • Strain localization behavior at melt-pool boundary depended on tensile direction. • Strain distribution in melt-pool interior can be affected by α-Al grain structure. [ABSTRACT FROM AUTHOR]

Determination of ideal aging processing is crucial for developing heat-treatable aluminum (Al) alloys with good mechanical performances. To make full use of the advantages of precipitation, in the present work, we firstly established a yield strength model from the perspective of thermo-kinetic synergy. Then, we proposed a two-steps scheme to design the aging processing of the heat-treatable Al alloys. By taken the 6xxx Al alloys as representatives, in the first-step, the optimal aging time (t p) at a given temperature, which derives from a high energy barrier for β" precipitation, is determined from the plateau endpoint of system energy dissipation curve. In the second-step, the optimal aging temperature (T A), which originates from a large driving force for β" precipitation, is determined as the transition point from the Guinier-Preston (GP) zones to the β" phase. The rationality of this scheme was verified via the model system of Al-1.0Mg-0.6Si alloy, the precipitation behaviors of which have been well studied. Finally, we applied this scheme to the Al-0.46Mg-1.04Si alloy, whose optimal aging processing parameters are determined as T A = 438 K and t p = 9.37 h. Subsequent parallel experiments confirmed that the alloy samples aged at this pre-designed aging processing condition behaves the highest yield strength of σ y = 279.20 MPa, agreeing well with the predicted value of 275.80 MPa from the present strength model. We further extended the applications to the 2xxx Al alloys. The predicted ideal aging processing parameters (3.50 h at 438 K) and the according yield strength (399.57 MPa) for the Al-4.62Cu alloy are in accordance with the experimental results. Our investigation provides an insightful guidance for designing the advanced Al alloys with high strength from the perspective of precipitation thermo-kinetic synergy. [ABSTRACT FROM AUTHOR]

Aluminum alloys, known for their high strength, good toughness, and lightweight properties, are widely used in aerospace, rail transportation, and other fields. 3D printing, as an emerging additive manufacturing (AM) technology, achieves the transformation from digital models to physical products through layer-by-layer material deposition. This processing method significantly enhances the flexibility of both design and manufacturing, while also enabling the efficient production of complex piping and intricate cavity structures. This paper comprehensively and systematically introduces the classification, structure, performance, defects, and elimination methods of AM aluminum alloys. It begins with an introduction to AM technologies and traditional aluminum alloys. Then, it discusses the classifications and performances of AM aluminum alloys, such as Al-Si, Al-Mg-(Sc, Zr), Al-Cu-(Mg), Al-Zn-Mg-(Cu), Al-Fe, Al-Ni, Al-Mn, and Al-based composites, and providing a detailed and comprehensive overview of the mechanical properties (both in horizontal and vertical directions), heat resistance, fatigue performance, creep behavior, corrosion resistance, impact resistance, and wear resistance of the alloys. It also discusses the potential defects of different types of alloys and their mitigation methods, especially the formation mechanisms and elimination methods of porosity, deformation, and cracking. Moreover, the role of refiners in 3D-printed aluminum alloys is separately demonstrated. Finally, the paper presents the practical applications and prospects of 3D printed aluminum alloys, aiming to establish a systematic and comprehensive framework to provide a multi-faceted overview of aluminum alloys in AM, offering valuable insights and guidance for scientific research and industrial applications. • This article takes a comprehensive approach, covering a wide range of aluminum alloys used in additive manufacturing: Al-Si, Al-Mg-(Sc,Zr), Al-Cu-(Mg), Al-Zn-Mg-(Cu), Al-Fe, Al-Ni, Al-Mn, and Al-based composites. • The article provides a thorough examination of various properties, including mechanical properties in both horizontal and vertical orientations, heat resistance, fatigue performance, creep behavior, corrosion resistance, impact strength, and wear resistance. • In discussing the defects associated with additive manufacturing aluminum alloys, the article details the different defects that can occur in different alloys and extensively describes methods for their elimination. • The article offers a very comprehensive perspective on the types, properties, structures, defects, and elimination methods of aluminum alloys in additive manufacturing, concluding with a discussion on specific applications and future prospects. [ABSTRACT FROM AUTHOR]

A novel mechanism for pore coarsening during hot rolling was proposed that the hydrogen in the ingot, driven by non-uniform hydrostatic pressure, accumulates into the tortuous shrinkage cavities at the thickness center of the slab. High pressure hydrogen gas gradually changes the stomatal curvature and finally leads to pore coarsening. • Pore coarsening phenomenon was confirmed in hot rolled Al-4.5 Mg alloy. • Distorted ambient grains reveal the macro-pores are formed by gas expansion. • Hydrogen migration was evaluated experimentally and its effect to pore coarsening was studied by numerical simulation. • A novel mechanism of pore coarsening is proposed by taking into account hydrogen gas. [ABSTRACT FROM AUTHOR]

The effects of total Zn and Mg content on the microstructure, tensile properties, and fatigue properties of Al-3.2xZn-xMg-1.66Cu alloy sheets were systematically investigated after aging at 120 °C for 24 h. As the total content of Zn and Mg increased, the recrystallized grains were gradually refined, and the types of precipitate particles did not change, all of which comprised Guinier Preston (GP) zones and η′ metastable-phase particles, whereas both the number and volume fraction of η′-phase particles increased gradually, where the particles were first coarsened and then refined. The η′-phase particles were largest (∼8.2 nm) in the alloy with the total Zn and Mg content of 5.15 wt.%. The grain boundary precipitate (GBP) gradually coarsened and the width of the precipitates free zone (PFZ) gradually decreased. When the total content of Zn and Mg was increased from 2.61 to 11.40 wt.%, the yield strength and tensile strength increased from 173 and 309 MPa to 554 and 620 MPa, respectively, whereas the elongation decreased from 29.9% to 8.5%. However, the fatigue strength of the alloy sheet first decreased from 149 to 119 MPa and then increased to 183 MPa under the condition of R = 0.1. The fatigue strength of the alloy sheet with total Zn and Mg contents of 5.15 and 11.40 wt.% were the lowest one and the highest one, respectively, and the latter was 54% higher than the former. • The η′-phase particle coarsens and then refines with the total content of Zn and Mg increased. • The change law of fatigue strength with increasing total content of Zn and Mg is different from tensile properties. • The Al-3.93Zn-1.22Mg-1.66Cu alloy sheet has the largest η′-phase particles and the lowest fatigue strength. • The correlation between the fatigue strength and the size of η′-phase particles of alloy sheets is negative. [ABSTRACT FROM AUTHOR]

The high design freedom of laser powder bed fusion (LPBF) additive manufacturing enables new integrated structures, which in turn demand advances in the process conditions and material design to exploit the full potential of this process. A computational multi-scale thermal simulation and metallurgical analysis of the aluminium alloy Scalmalloy® were used to develop and present a specific process window to enable an in-situ heat treatment during LPBF. High resolution analysis and synchrotron experiments on specimens manufactured in this process window revealed a major proportion of nano-sized A l 3 (S c x Z r 1 − x ) solute-clusters were already present in the as-built state, as predicted by simulation. Supported by this experimental research, the new processing concept of in-situ heat treatment yielded the highest recorded strength values combined with high ductility directly after LPBF for Scalmalloy®. This advancement in LPBF enables highly complex, thin-walled structures directly made from a high-strength, lightweight material, which is not possible with conventional processes that require a subsequent heat treatment cycle. [Display omitted] • The applicability of an integrated (in-situ) heat treatment during laser powder bed fusion for a high-strength aluminium alloy was shown. • A multi-scale simulation was performed to identify a suitable build platform heating for in-situ heat treatment. • High-resolution microstructural analysis showed the presence of Sc-rich clusters already in the as-built material state. • Tensile tests could confirm the strength increase by cluster formation, showing the same level of strength as peak-aged Scalmalloy® material. • The up-quenching concept of AlMgSi alloys was adapted to explain the significant increase in as-built tensile strength. [ABSTRACT FROM AUTHOR]

The high design freedom of laser powder bed fusion (LPBF) additive manufacturing enables new integrated structures, which in turn demand advances in the process conditions and material design to exploit the full potential of this process. A computational multi-scale thermal simulation and metallurgical analysis of the aluminium alloy Scalmalloy® were used to develop and present a specific process window to enable an in-situ heat treatment during LPBF. High resolution analysis and synchrotron experiments on specimens manufactured in this process window revealed a major proportion of nano-sized A l 3 (S c x Z r 1 − x ) solute-clusters were already present in the as-built state, as predicted by simulation. Supported by this experimental research, the new processing concept of in-situ heat treatment yielded the highest recorded strength values combined with high ductility directly after LPBF for Scalmalloy®. This advancement in LPBF enables highly complex, thin-walled structures directly made from a high-strength, lightweight material, which is not possible with conventional processes that require a subsequent heat treatment cycle. [Display omitted] • The applicability of an integrated (in-situ) heat treatment during laser powder bed fusion for a high-strength aluminium alloy was shown. • A multi-scale simulation was performed to identify a suitable build platform heating for in-situ heat treatment. • High-resolution microstructural analysis showed the presence of Sc-rich clusters already in the as-built material state. • Tensile tests could confirm the strength increase by cluster formation, showing the same level of strength as peak-aged Scalmalloy® material. • The up-quenching concept of AlMgSi alloys was adapted to explain the significant increase in as-built tensile strength. [ABSTRACT FROM AUTHOR]

Enhanced solution-treatment (EST) tends to increase the strength of aluminum alloys by increasing the solute concentrations due to the sufficient dissolution of soluble constituents. However, results of spray-formed 7055 Al–Zn–Mg–Cu alloy indicate that the strength increment occurs only in hot-extruded alloy not in cold-rolled one and is related to increasing the average Taylor factor (M A) instead of the solute concentrations. The increased M A of hot-extruded alloy is attributed to the transformation of some S texture grains into the Copper texture ones with increasing the solution-treating temperature, whereas recrystallization and grain growth of cold-rolled alloy exerts little effect on the M A. [ABSTRACT FROM AUTHOR]

In this study, a hybrid wire arc additive manufacturing (WAAM) and interlayer friction stir processing (IFSP) approach was utilized to enhance the quality of 2024 aluminum alloy components. The defects characteristic, microstructure evolution, and mechanical properties of the fabricated components and after T6 heat treatment were analyzed systematically. Our analysis reveals that IFSP can break and dissolve the eutectic phases, significantly reduce porosity defects and refine the grain size of the as-deposited materials, thus improving the overall mechanical properties. Notably, compared to the WAAM as-deposited component, the yield strength (YS) and ultimate tensile strength (UTS) in the top-layer stir zone (SZ) of IFSP component increased from 154 ± 3 to 267 ± 2 MPa, and from 258 ± 12 to 360 ± 3 MPa, respectively. However, in the middle-layer SZ, S-phase precipitation and coarsening induced by thermal cycling during additive manufacturing slightly reduced the tensile properties. Post-T6 heat treatment led to uniformly distributed properties in the IFSP component along both horizontal and vertical directions, with the YS, UTS, and elongation (EL) averaging 353 ± 9 MPa, 470 ± 4 MPa, and 10.5 ± 1.6%, closely matching those of wrought counterparts. The significant improvements in mechanical properties are primarily attributed to the elimination of porosity and precipitation of fine needle-like S-phase. This research not only demonstrates the potential of IFSP in enhancing the mechanical properties of WAAM-fabricated 2024 aluminum alloy but also offers a promising technique for producing high-quality components suitable for high-performance aerospace applications. [ABSTRACT FROM AUTHOR]

In the present study, the dislocation configuration in 7005 aluminum alloy plate stored at room temperature for 96 h following solution quenching was changed by pre-stretch at room temperature for various deformations, to reveal its influence on the tensile properties, especially fatigue life and fatigue fracture characteristics of alloy plate. The results show that with the increase in pre-strain deformation to 16%, the thickness of the thin strip grains decreases from 7.70 to 6.31 μm, the dislocation density in the matrix of the plates gradually increases, especially the changing law of dislocation distribution inside a grain and among grains is "nonuniform-uniform-nonuniform". The plate exhibits an obvious hardening effect, the strength and hardness increase, but the elongation decreases monotonically. However, the fatigue performance of the alloy plates under the conditions of a maximum stress of 180 MPa and a stress ratio of R = 0 is improved by 3∼16% pre-strain deformation, the alloy plates underwent 12% pre-strain deformation have the longest fatigue life that is (1.10 ± 0.16) × 106 cycles, due to the higher dislocation density and the uniform dislocation distribution inside a grain and among grains, which is 169% longer than that of the alloy plates without pre-strain. The results provide an important theoretical basis and some experimental data for improving the fatigue performance of 7005 aluminum alloy plate used in high-speed railway and aviation industries. • Dislocation distribution is "nonuniform-uniform-nonuniform" with the increasing pre-strain. • Dislocation configuration has significant impact on the fatigue fracture behavior. • 12 % pre-strain deformation of alloy plates can prolong the fatigue life to 1.69 times. • A schematic diagram of fatigue crack propagation was created. [ABSTRACT FROM AUTHOR]

This study rigorously examines the AA1060 aluminum alloy's mechanical properties across different thermal conditions (298K–77K) and orientations (RD-ND and TD-ND). Through annealing at 350 °C for 50 min followed by extensive mechanical testing at ambient and cryogenic temperatures, the study delves into the microstructural evolution and deformation mechanisms utilizing Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Findings indicate a pronounced increase in yield strength, tensile strength, and ductility with decreasing temperature. Notably, RD-ND oriented samples demonstrated enhanced mechanical strength over TD-ND oriented samples under both temperature regimes, underscoring the alloy's pronounced anisotropy. This comprehensive study illuminates the AA1060 alloy's temperature-dependent mechanical enhancements and anisotropic behavior, emphasizing the significant impact of microstructural orientation on its mechanical properties. The insights gained illuminate the AA1060 alloy's temperature-dependent and anisotropic behaviors, highlighting microstructural orientation's important role in its mechanical properties, with profound implications for aluminum alloy application across varying temperature and stress conditions. [ABSTRACT FROM AUTHOR]

A novel Al–Si–Cu alloy was designed for additive manufacturing of automotive components, such as pistons and supercharger rotors, requiring a combination of elevated temperature properties and high cycle fatigue strength. The alloy was designed with an Al–Si hypereutectic chemistry to exploit the formation of primary Si nucleants to enable an equiaxed as-printed microstructure during laser powder bed fusion (LPBF). The alloy design space was assessed using a combined integrated computational materials engineering (ICME) approach with melt-spinning experiments to select a chemistry exhibiting primary Si nucleants acting as heterogeneous grain nucleation sites. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) of the LPBF as-printed samples revealed primary Si particles with a fully equiaxed grain structure and no apparent texturing as evaluated using electron backscatter diffraction (EBSD). High-resolution scanning transmission electron microscopy (STEM) revealed sub-micron Si particles and Al 2 Cu θ-phase precipitates which result in enhanced room and elevated temperature mechanical strength (room temperature: UTS: 449 ± 10 MPa, YS: 336 ± 12 MPa) as compared to commercial Al10SiMg (UTS: 417 ± 3 MPa, YS: 236 ± 6 MPa). [ABSTRACT FROM AUTHOR]

Friction stir-derived solid-state processes leverage the synergistic effect of frictional heating and intense shear deformation to achieve localized microstructural modification for the improvement of mechanical properties. In the present work, a novel processing route called solid-stir extrusion (SSE) has been explored for continuous, high-rate extrusion of a high strength non-age-hardenable-AlMgSc alloy. In the current study, loss of strength associated with frictional heating during the process is mitigated as elevated strength is observed in as-extruded condition, thereby eliminating the need for post process heat treatment. The effect of process attributes on mechanical property and microstructure evolution was investigated. The SSE process caused extensive grain refinement and fragmentation of thermally stable Al 3 Sc intermetallic periodically at shear bands, which contributes to the elevated mechanical strength. The spatial variation in mechanical properties and microstructural heterogeneity was characterized using nanoindentation and microstructural correlation. The current findings indicate the significance of the process-specific alloy design approach to increase performance of material in as-processed condition. • Novel solid-stir extrusion (SSE) technique is developed for continuous rod extrusion. • The extruded AlMgSc alloy was subjected to microstructural and mechanical characterization. • The SSE process resulted in a distinctive material flow pattern, leading to a heterogeneous microstructure that exhibited a synergy between strength and ductility. • Nanoindentation analysis contributed to the understanding of microscale variations in mechanical properties. • The alloy chemistry effectively minimized the strength reduction observed in previous studies. [ABSTRACT FROM AUTHOR]

Al/Ti laminated metal composites (LMCs) benefit from a bionic laminate structure that allows for simultaneous strength and plasticity enhancement. However, the Al layer with lower strength is always the first to crack under stress, resulting in declining mechanical properties of the Al/Ti LMCs. In this study, 2024 Al-GNPs/TC4 LMCs were prepared by replacing the conventional Al or Al alloy layers with 2024 Al-GNPs composites. Its ultimate tensile strength of 757 MPa surpasses that of almost all other Al/Ti LMCs. The lamellar structure and GNPs were found to have a synergistic effect in enhancing the mechanical properties by inhibiting crack extension across and within the layers, respectively. The hindrance of crack extension by the lamellar structure is primarily due to strain delocalization in TC4, as confirmed by phase-field-crystal simulation. On the other hand, GNPs impede crack extension through passivation and deflection, which was revealed by molecular dynamics to be attributed to dislocation hindrance and load transfer. Furthermore, it was confirmed that the main factors affecting the formation of intermetallic compounds are diffusion coefficient and solid solubility. This work provides new insights for breaking the performance limits of LMCs. [ABSTRACT FROM AUTHOR]

Aluminum alloy is widely used in high˗speed train bodies. However, compared with the base material, the tensile strength and elongation of its laser welded joints are significantly reduced, which limits the lightweight application of the next generation of high˗speed trains. The research in this article indicates that laser welding with Ca micro˗alloyed 5356 filler metal has changed the mechanical properties and microstructure of the weld seam. Without the Ca in the filler metal, the strength and elongation of the laser welded joint are only 215.5 MPa and 3.1 %. When the Ca content in the filler metal reaches 0.04 wt%, the laser welded joint has high tensile strength and maximum elongation, which are 251.5 MPa and 9.7 %, respectively. As the Ca content increases, the grain size of the welded joint gradually decreases, and the limiting effect of Ca element on the growth of α˗Al grains is the main reason for grain refinement. In addition, the addition of Ca transforms the coarse Fe˗rich phase in the weld into a fine˗grained second phase, while promoting the formation of deformable nanoparticles γ˗Al 12 Mg 17 , leading to the accumulation of dislocations and successfully improving the strength and plasticity of laser welded joints. When the Ca content further increases, the second phase grows, and the tensile strength and plasticity of the joint slightly decrease, but are still higher than that of the joint without Ca. [ABSTRACT FROM AUTHOR]

In this paper, 2A12-T3 aluminum alloy is first solution-treated and then experienced an artificial aging for different time to induce different S phase characteristics. By using this method, the texture formation behavior solely contributed from S phase characteristic could be determined during hot rolling. It is found that the increase of S phase in size and density has a positive effect on Brass texture formation, which is attributive to the increased Dislocation Shear Slipping (DSS) near S /Al interface. The relative slip tendency factor (M s x ) is proposed to quantitatively evaluate the impact of S phase characteristic on Brass formation. It is revealed that Brass volume fraction (V Brass) has a better positively linear relationship with M s x than texture intensity. Then, the effect of Brass texture on tensile property is analyzed in details. Crystal plasticity simulation shows that Brass texture can improve the yield stress and tensile strength and simultaneously keep the elongation. Comparatively, the rolling sheet aged for 3 h obtains an excellent combination of strength and ductility. [ABSTRACT FROM AUTHOR]

The aluminum alloys produced by friction stir based AM were commonly characterized by fine-grains and coarsened precipitates. Abnormal grain growth (AGG) occurred often when the deposited fine-grained aluminum alloys were subjected to a T6 heat treatment, limiting the application of the friction stir based AM technologies and the produced components. In this study, friction surfacing deposition additive manufacturing (FSDAM) were developed to fabricate components of commercial 7075 high-strength aluminum alloys. The effect of post-processing heat treatment on the microstructure and mechanical properties of the fine-grained 7075 aluminum alloys produced by FSDAM were investigated systematically. The new post-processing heat treatment that was able to generate nano-sized precipitates without AGG was developed for the deposited 7075 aluminum alloys. The ultimate tensile strength, yield strength and ductility of the deposited 7075 aluminum alloys were comparable to those of the extruded 7075 aluminum alloys, offering a new solution for additive manufacturing high strength aluminum alloy components cost effectively. [ABSTRACT FROM AUTHOR]

A novel process combined intensive melt shearing direct chill (MS-DC) casting technology, shortened homogenization treatment, hot rolling and intermediate annealing (MS-DC combination process) was proposed to inhibit the growth of coarse Fe-rich primary intermetallic phases (IMPs) in the center of conventional DC cast aluminum alloy ingots and avoid the formation of large-sized T phase caused by long-time homogenization. The analysis of the dissolution kinetic of the primary phase showed that MS-DC as-cast structure provided favorable conditions for shortening the homogenization treatment and the nano-sized T phases precipitated during MS-DC combination process. Besides, the MS-DC combination process increased the number of randomly oriented subgrains and the drag force of recrystallization in the cold-rolled sheet, generating refined grains and random weak textures during solution treatment. Furthermore, more types of textures existed in the solution-treated MS-DC sheet, the mixed structure of β fiber deformation texture, CubeND and Cube texture decreased the planar anisotropy (Δr) value and increased the average plastic strain ratio (r ave) value, which is conductive to the improvement of deep drawability. [ABSTRACT FROM AUTHOR]

Al–6%Mg-Sc-Zr alloys with a combined Sc and Zr ratio of 0.32 wt% make up the focus of this research. The content of Sc and Zr varied with an increment of 0.02%. Their ultrafine-grained (UFG) microstructure was formed with Equal Channel Angular Pressing (ECAP). Superplasticity tests were performed at temperatures ranging from 300 to 500 °C and at a strain rate varying between 3.3·10−3 and 3.3·10−1 s−1. The values of strain hardening factor (n), strain rate sensitivity factor (m), and superplastic deformation threshold stress (σ p) were determined. The microstructure and failure patterns of the alloys post superplasticity tests were studied. The effect of the Sc/Zr ratio on the superplastic behavior, cavitation fracture and dynamic grain growth of UFG Al–6%Mg alloys was investigated. The satisfiability of Hart's criterion for calculating uniform deformation value under superplastic conditions was verified. Grain boundary sliding and intragranular deformation make comparable contributions to superplastic flow in the UFG aluminum alloys under study. Al–6%Mg-0.20%Sc-0.12%Zr (Sc/Zr = 3.3 at.%) and Al–6%Mg-0.18%Sc-0.14%Zr (Sc/Zr = 2.8 at.%) alloys exhibit the highest superplasticity. Shown that changes in the Sc/Zr ratio affect the precipitating mechanism, spatial distribution and composition of the precipitating particles Al 3 (Sc x Zr 1-x). The optimal Sc/Zr ∼2.6–3.3 (at.%) ratio for the Al–6%Mg alloy corresponds to an Al 3 (Sc 0.5 Zr 0.5) and Al 3 Sc precipitated particles. The large Al 3 Zr particles formed through the discontinuous precipitation mechanism was detected at Sc/Zr < 1 (at.%). [ABSTRACT FROM AUTHOR]

The high-performance additive manufacturing of relatively small aluminum alloy components has been widely proven successful. However, wire arc additive manufacturing (WAAM) has always been challenging in achieving uniform microstructure and high mechanical properties when manufacturing large-sized parts. Therefore, this study used cold metal transition wire arc additive manufacturing (CMT-WAAM) to prepare Al-5.49Cu-0.4Mn-0.29Cd (ACMC) alloy to obtain a uniform microstructure and improve its mechanical properties. The results show that the as-deposited (AD) samples have an obvious layered deposited structure. The grains in the microstructure are all equiaxed crystals and a large amount of copper-rich eutectic phase precipitates at the grain boundaries. After heat treatment, the vast majority of the eutectic phase dissolves, and θ'phase, with a size of 100–200 nm, uniformly precipitates in the α-Al matrix. The ultimate tensile strength (UTS) and yield strength (YS) of the heat-treated (HT) specimen can reach 483.7 MPa and 412.3 MPa, respectively. There is no significant difference in the mechanical properties between the transverse and longitudinal directions of thin-walled samples. Based on experimental results and theoretical analysis, the strengthening mechanism and fracture mechanism of CMT-WAAM aluminum alloy were revealed. This work provides a theoretical basis for the microstructure optimization and mechanical performance improvement of ACMC alloy, which is of great significance for the high-performance preparation of large-sized components in the aerospace field. • The microstructure consisting of equiaxed grains was obtained. • Al3(Zr, Ti) hindered the change of grain size after heat treatment. • The ultimate tensile strength after heat treatment reached 483.7 MPa. • The strengthening mechanism of Al–Cu–Mn–Cd alloy was revealed. • The fracture mechanism of Al–Cu–Mn–Cd alloy was analyzed. [ABSTRACT FROM AUTHOR]

Existing additively manufactured aluminum alloys exhibit unfavorable tensile strength above 200 °C due to the strengthening phase coarsening, microstructure instability and cracking. This paper designed a novel Al-5Fe-1Mg-0.6Sc-0.3Zr alloy for powder bed fusion using laser beam (PBF-LB) with tensile strength of 189 MPa at 400 °C, which is the highest value reported. The main strengthening phases of the alloy were Al 6 Fe particle and nano-scaled L1 2 -Al 3 (Sc, Zr) precipitates. The exceptional high-temperature performance is attributed to high volume fraction (∼35%) of nanoprecipitates Al 6 Fe modified by Sc and Zr elements, showing enhanced thermal stability and refined particle dimension. The addition of Sc and Zr elements also significantly retards the phase transformation from Al 6 Fe to θ-Al 13 Fe 4 and inhibits brittle θ phase growth during thermal exposure. IMPACT STATEMENT: The paper designed a heat-resistant Al-Fe-Mg-Sc-Zr alloy with exceptional high-temperature performance (UST of 189 MPa at 400 °C) for PBF-LB. Adding Sc/Zr element can effectively enhance the thermal stability of Al 6 Fe and delays its transition to Al 13 Fe 4 phase. [Display omitted] [ABSTRACT FROM AUTHOR]

Achieving high-quality 7075 high-strength aluminum alloy manufactured via directed energy deposition-arc (DED-Arc) remains challenging due to its sensitivity of microstructures and properties to heat inputs. This study examines how TiC nanoparticles can effectively reduce the adverse effects of high heat input from the arc on the surface morphology, microstructure, and properties of 7075 aluminum alloy deposits. The surface morphology, defects, microstructures, and mechanical properties of the deposited alloy parts were characterized. The analysis revealed that reducing the heat input results in smoother surface morphology but has little effect on the number of defects, grain morphology, grain size, and tensile strength. Even under various heat inputs, all deposited samples containing TiC nanoparticles exhibit equiaxed grain structures with an average grain size of approximately 8.98 ± 0.27 μm and possess a tensile strength exceeding 500 MPa with minimal variance. Further studies involving microstructures and computational fluid dynamics suggest that the incorporation of TiC nanoparticles mitigates the impact of thermal dynamic conditions within the molten pool. It was discovered for the first time that there is a significant lattice mismatch of about 18% between the crystal planes of TiC and the Al-matrix in the deposited samples. This mismatch increases the free energy of the growth phase, effectively creating a pinning effect for the growing grains. Consequently, this nanoparticle-induced physical barrier disrupts the conventional control of grain growth dictated by thermodynamic conditions, effectively limiting grain size under various heat inputs by arc. This work demonstrates a promising strategy to reduce the sensitivity of microstructure and properties to heat input during DED processes. [Display omitted] • The TiC-nanoparticles modified raw materials deposited three crack-free of 7075 thin walls over a wide heat input range. • The microstructure and mechanical properties are not sensitive to large heat input variation range. • The physical barrier established by TiC-nanoparticles inhibited the effect of thermal undercooling on grain growth. [ABSTRACT FROM AUTHOR]

Cold Butt Welding (CBW) exploits plastic deformation to enable room temperature fabrication of joints with comparable strength to their base metals. Challenges arise when CBW involves alloys with very different mechanical properties, where the necessary conditions to reach their plastic regime differ significantly. The present study unravels the conditions at the interface under which dissimilar AA1070 and AA6082 aluminum wires achieve bonding. Statistical studies were performed to establish a minimum deformation threshold required for successful bonding. The joints were characterized through optical light microscopy, scanning electron microscopy, and micro and nano hardness examinations. In-situ tensile testing was conducted to evaluate the bond strength and failure mechanism. It was found that during the CBW process, at increasing force, the constraints generated by the clamping apparatus on the wires are such that the soft alloy can exceed its ultimate strength and eventually reach the yielding stress of the hard alloy at the interface, allowing both materials to plastically deform and bonding to occur. Moreover, the deflection in the flow of both materials leads to grain refinement and crystalline reorientation inside a region centred around the bonded interface. The severely deformed area was proven by hardness and tensile testing to be the strongest part of the weld, typically identified as the mechanically affected zone. [Display omitted] • A study on Cold Butt Welding (CBW) of dissimilar aluminum wires is provided for the first time. • Higher deformation is required for dissimilar joints to achieve bonding if compared with similar ones. • Plastic deformation of both pieces initiates the oxide removal, which triggers the bonding mechanism. • In the dissimilar joints, the soft alloy, thanks to the constraints given by the clamps, reaches the yielding strength of the hard alloy. • Severe grain refinement produces a work-hardened region that confers the joints higher strength than that of the base metals. [ABSTRACT FROM AUTHOR]

The low-cycle fatigue (LCF) behaviour of a large 7075 aluminium alloy bar was investigated, and the results indicated that the microstructure at the center (0R) and surface section of the bar (R) were different in terms of grain sizes and textures. The microstructure of the 0R specimen was characterised by coarser elongated grain and higher <111> texture intensity compared to that of the R specimen. The LCF life of the 0R specimen was higher than that of the R specimen at a strain amplitude range of 0.6%–0.9%, thereby indicating the dominant effect of higher texture intensity. However, the 0R specimen sustained short LCF life at low strain amplitudes of 0.4% and 0.5%, indicating the predominant effect of grain refinement. The fracture analysis results indicated that there were wider striations for the 0R specimen at a strain amplitude of 0.4%. Interestingly, the yield strength, ultimate tensile strength and elongation of the 0R specimen were higher than that of the R specimen. The higher mechanical properties of the 0R specimen was consistent with its longer low cycle fatigue life at strain amplitude range of 0.6%–0.9%. Moreover, the features of the fracture, including fracture initiation and fast fracture regions, were also elaborated. The competition of grain sizes and texture evolutions determined the LCF life of the alloy depending on the strain amplitude range: the grain size effect gradually overshadowed that of the texture with decreasing strain in terms of fatigue life. [ABSTRACT FROM AUTHOR]

The present study investigates the laser powder bed fusion of Al 2024 alloy. The Al 2024 is one of the most widely used aluminium alloys in aerospace industries owing to its excellent mechanical properties such as high strength-to-weight ratio, high fatigue and fracture strength, etc. However, the additive manufacturing of the Al 2024 alloy is scarce in literature due to its high solidification cracking and low processing window. The current study explores the composition changes tailored for the additive process to promote columnar to equiaxed transformation, constitutional supercooling and heterogeneous nucleation. The Al 2024 alloy was modified using Ti to eliminate solidification cracking. The mechanical characteristics such as tensile, hardness, and fracture toughness were evaluated for varying orientations in as-fabricated and T6 samples, and the corresponding strengthening mechanisms were explored in detail using the microstructural features. The maximum tensile strength obtained in the T6 condition (483 MPa) was comparable to the wrought Al 2024 and the maximum hardness and fracture toughness were better compared to the wrought counterparts. The different precipitates, such as Al 2 Cu/Al 2 CuMg, evolved during T6 heat treatment, along with the ultrafine grains produced due to Ti addition, were observed to be the primary strengthening mechanism contributing to the high strength of the additive samples. [ABSTRACT FROM AUTHOR]

To satisfy the requirements of formability, strength-toughness, and corrosion resistance for laser additive manufacturing of lightweight aluminum alloy brake discs, this study adopted a thermodynamic design method incorporating Mn, Cu, Er, and Zr elements to develop multi-element Al–Mg–Zn-(Mn–Cu–Er–Zr) alloy. The optimized laser cladding process was employed to prepare a novel alloy sample. The results indicate that a novel T-AlMgZnCuZrEr phase with a distinct structure compared to the conventional T-phase in Al–Mg–Zn alloys was observed in the sample prepared by synergistic addition of Mn, Cu, Er, and Zr. Owing to the significant strengthening and toughening effects of the novel T-phase, the compressive strength and toughness product, along with the corrosion potential of the laser cladded sample reached 26520 MPa2 m1/2 and −0.73 V, respectively, which were 27% and 39% higher than those of Al–Mg–Zn alloy. The precipitation and growth mechanism of the novel T-phase was elaborated, and the kinetic equation for the in-situ precipitation of the T-phase was established. A multi-component design method for strengthening and toughening Al alloy to improve the performance by controlling microstructure through laser cladding was obtained, which provides a valuable reference for laser cladding to prepare lightweight aluminum alloy with high strength-toughness and corrosion resistance. [ABSTRACT FROM AUTHOR]

The 4032 aluminum alloy is a high-Si deformation aluminum alloy, that is commonly generated through forging due to the difficulties involved in its direct casting. In this work, the 4032 aluminum alloy is innovatively prepared via a squeeze casting process, and the Al-6Nb-1.5Ti-0.5B refining agent is incorporated to enhance its mechanical properties. A range of analytical techniques are subsequently employed to analyze the grain refinement mechanism of Al-6Nb-1.5Ti-0.5B under squeeze casting conditions. It was found that the microstructure of the aged 4032 aluminum alloy after refinement treatment was mainly composed of α-Al grains measuring <100 μm in size, in addition to a eutectic Si phase, that is accompanied by stacked dislocations and diffusely distributed Q′-Al 5 Cu 2 Mg 8 Si 6 and θ′-Al 2 Cu phases. The yield strength of the alloy reached 340 MPa, its tensile strength was 404 MPa, and the elongation was 4.1 %. In the presence of the Al-6Nb-1.5Ti-0.5B refiner, the generation of nucleation cores (e.g., MAl 3 (M = Ti, Nb)) in the melt led to a significant reduction (∼50 %) in the α-Al grain size of the aged 4032 aluminum alloy (i.e., 95.1 ± 21.0 μm), compared with the standard alloy. After the T6 heat treatment of the refined 4032 aluminum alloy, the size of the precipitation phase was reduced by 36.8 %, and fine silicon particles with a spherical morphology and a more random distribution were observed. No obvious selective orientation was detected, and the fracture morphology improved significantly, thereby leading to a synergistic improvement in the strength and toughness of the alloy. • The effect of Al-Ti-Nb-B under squeeze casting on the properties of 4032 is studied. • The prepared alloy has comparable properties to forging after T6 heat treatment. • The microstructure evolution model is established based on the experimental results. • The theoretical yield strength is calculated and in line with the actual situation. • It shortens the production process and high-performance Al-Si alloys are prepared. [ABSTRACT FROM AUTHOR]

In this work, a new Al–Mg–Zn alloy was designed based on thermodynamic calculations combined with the concept of cooperative strengthening and toughening. The influence of different aging processes on microstructure and mechanical properties of the designed Al–Mg–Zn alloy was studied using experimental techniques including hardness testing, room-temperature tensile testing, EBSD, and HRTEM. The results indicate that after four different aging heat treatments, fine and uniformly distributed nano T-Mg 32 (Al, Zn) 49 phases have precipitated within the grains. Compared to single-stage aging (140 °C/36 h, 180 °C/7 h), two-stage aging (90 °C/24 h + 140 °C/18 h, 90 °C/24 h + 180 °C/5 h) resulted in a smaller size and an increased number density of precipitated phases within the grains. After the aging process of 90 °C/24 h + 140 °C/18 h, the grains exhibited the smallest precipitated phases, being of 2.77 nm in size and a number density of 1.06 × 1023 #/m³. Additionally, TEM diffraction spot analysis identified the presence of Al 3 (Sc, Zr) precipitates within α-Al matrix. Under the aging process of 90 °C/24 h + 140 °C/18 h, the alloy exhibited superior mechanical properties with a tensile strength of 566 MPa, yield strength of 477 MPa, and elongation of 16.5%. The primary strengthening mechanisms of the presently investigated Al–Mg–Zn alloy include precipitation strengthening, solid solution strengthening, and grain boundary strengthening. A yield strength model considering various strengthening mechanisms is used to predict the yield strength based on thermodynamic calculations and experimental data. The research findings will offer theoretical insights guiding the design of compositions and heat treatment schedule for aluminum alloys. [ABSTRACT FROM AUTHOR]

In this study, 2195 Al–Cu–Li alloys with a remarkable layered structure were fabricated through spray deposition, hot extrusion, and three distinct heat treatment processes (namely, solid solution treatment (ST), artificial peak-aging (PA), and artificial over-aging (OA)). The samples subjected to varying heat treatments are revealed to exhibit an exceptional combination of strength and ductility at 77 K, in contrast to their counterparts at 298 K. Specially, the mechanical properties of the PA samples are enhanced to various degrees with decreasing temperature from 298 K to 77 K. It is found that the synergistic effects of dense dislocations and uniform T 1 precipitates, as well as their extensive interactions, are responsible for the exceptional strain hardening capacity at cryogenic temperature. Particularly, multiple slip systems and the temperature-dependent relative slip distance are beneficial for the formation of dense dislocations and thus for enhancing ductility at 77 K. Furthermore, the observation of rare and small microcracks, along with intergranular delamination at 77 K, suggests that layered structures impede the plastic instability of the alloy and improve its ductility. These findings provide valuable insights into the deformation behaviors of high-strength aluminum alloys for cryogenic applications. • The spray deposited 2195 Al–Cu–Li alloy displays a superior strength-ductility synergy at cryogenic temperature. • Superior cryogenic strength-ductility synergy of the PA sample stems from the synergy of multiple strengthening mechanisms. • The temperature-dependent relative slip distance enhances ductility at 77 K. • Observations of rare and small cracks and intergranular delamination at 77 K improve its ductility. [ABSTRACT FROM AUTHOR]

The microstructural and mechanical properties of ultrasonic spot-welded (USWed) joints of AA7072-clad AA7075-T6 alloy to galvanized HSLA steel are investigated. The tensile lap shear strength increased with increasing welding energy and reached ∼145 MPa at a welding energy of 2500 J. The dissimilar joints also exhibited a longer fatigue life than other USWed Al-steel joints reported in the literature. In the present dissimilar ultrasonic spot welding, direct Al–Fe interactions to form intermetallic compounds were prevented and accelerated inter-diffusion between Al and Zn occurred along with localized melting at higher welding energy levels. The subsequent fast cooling led to the formation of an Al–Zn eutectic layer (∼40 μm thick) with fine structures at the interface of the dissimilar joints, which displayed a robust sticking capacity as demonstrated by the extensive shear dimples on both tensile and fatigue fracture surfaces. While interfacial failure occurred in the majority of tensile lap shear and fatigue tests, both modes of interfacial failure and TTT (transverse through-thickness) failure were present at lower cyclic stress levels during fatigue, with the interfacial failure being slightly more dominant in the two competitive failure modes. [ABSTRACT FROM AUTHOR]