Search

The efficient hydrogen-production through the Aluminum-water reaction has become a prominent subject of interest. The impediment encountered in the reaction can be effectively alleviated by Aluminum-based alloy. In this study, density functional theory (DFT) was utilized to explore the mechanism of water decomposition stage on the surface of aluminum and gallium alloy (AGA). Through surface reaction calculations of 12 stable AGA configurations, it was gradually revealed that the optimal alloy ratio was gallium-to-aluminum at 3.5:1. Analysis of the density of states (DOS) indicated that the presence of gallium amplified the activity of surface aluminum. Moreover, frontier orbital theory and charge density maps confirmed that, due to the weak interaction between Ga and ions, the presence of H 2 inhibited Ga passivation, thereby enhancing the reactivity of AGA. This paper provided valuable insights into the surface reaction mechanisms of AGA using DFT, offering theoretical support for hydrogen production processes. • Density functional theory investigated the early stages of AGA-water reaction. • Modeling AGA (Ga proportions 73.8%–81.2%) yields 12 stable configurations. • Ga:Al = 3.5:1 exhibits highest energies for O 2 , H 2 O, and co-adsorption. • Ga enhances AGA's catalytic activity, shown in DOS graphs comparisons. • AGA plays dual roles in surface hydrogen dynamics. [ABSTRACT FROM AUTHOR]

The 6061‑aluminum alloy is most used in marine engineering equipment. We used composite co-deposition to prepare a Cu/Co-Mo-Ce alloy coating on the aluminum alloy surface, which not only solved problems related to the ready corrosion of aluminum alloy in marine environments and the difficulty of directly preparing protective coatings but also solved problems associated with the fact that CoMo alloy form many holes by introducing the rare earth Ce. An exploration of the plating process revealed that when the concentration of the other main salts was unchanged and the concentration of Ce3+ was 0.012 mol·L−1, the Cu/Co-Mo-Ce had the flattest morphology, and the best corrosion resistance. The coatings were characterized and analyzed using SEM, EDS, XRD, and XPS. Finally, the ions deposition processes were tested via cyclic voltammetry and chronoamperometry and AC impedance. [ABSTRACT FROM AUTHOR]

Diffusion coefficients in the BCC phase of the Al–Nb–V ternary system are studied for the first time, including an assessment of the atomic mobilities. Ternary interdiffusion coefficients are obtained from the intersecting diffusion paths of several sets of diffusion couples that are annealed at both 1100 °C and 1200 °C. Existing experimental data from the pertinent binary systems are also employed for the assessments of atomic mobilities using the 1-parameter Z-Z-Z binary diffusion coefficient model developed by Zhong et al [1]. Interdiffusion coefficients in the BCC region of the Al–V system are also extracted through a forward-simulation analysis and incorporated into the mobility modeling. A complete description of diffusion in the BCC phase of the Al–Nb–V system is presented following the Binary and Cross-Binary Parameters Only (BCBPO) model developed by Zhong and Zhao [2]. Our data will be valuable input to diffusion-related simulation of refractory high entropy alloys containing aluminum. [ABSTRACT FROM AUTHOR]

Radiation-based gauges have been widely utilized in the industry as a dependable, non-destructive method of measuring metal layer thickness. It is only possible to trust the conventional radiation thickness meter when the material's composition is known in advance. Thickness measurement errors are to be anticipated in contexts like rolled metal factories, where the real component of the material could diverge greatly from the stated composition. An X-ray-based device was suggested in this study to measure aluminum sheet thickness and identify the type of its alloys. Transmission and backscattered X-ray energy were recorded using two sodium iodide detectors while a 150 kV X-ray tube in the described detection system was operated. Aluminum layers of varying thicknesses (2–45 mm) and alloys (1050, 3105, 5052, and 6061) were simulated to be placed between the X-ray source and the transmission detector. The development of radiation-based systems used the MCNP code as a very powerful framework to imitate the detecting architecture and the spectra acquired by the detectors. The recorded signals were transferred to the frequency domain using the Fourier transform, and the frequency characteristics were extracted from them. Two GMDH neural networks were trained using these characteristics: one to identify the alloy type and another to determine the aluminum layer's thickness. The classifier network had a 92.2% success rate in identifying the alloy type, while the predictive network had a 1.9% error rate in determining the thickness of the aluminum layer. By extracting important characteristics and using powerful neural networks, this study was able to improve the precision with which aluminum layer thickness was measured and correctly identify the alloy type. The suggested method is used to determine the thickness of aluminum and its alloy sheets and may also be applied to other metals. • An X-ray-based device was suggested to measure aluminum sheet thickness and identify the type of its alloys. • Transmission and backscattered X-ray energy were recorded using two NaI detectors. • The recorded signals were transferred to the frequency domain using the Fourier transform. • Two trained GMDH neural networks determined the alloy type and the aluminum layer's thickness. [ABSTRACT FROM AUTHOR]

The 6016 aluminum alloy has good plasticity but low strength. In this work, Al-Ti-Sc master alloy was prepared by thermite reduction method in order to obtain an effective grain refiner with a simplified preparation process and a reduced cost. The refining effects of the ternary master alloy on the 6016 aluminum alloy were checked to improve the strength and plasticity simultaneously. The chemical reactions during the preparation process of the Al-Ti-Sc master alloy was studied by thermodynamic software of HSC 6.0. The content of Sc and Ti in the master alloy reaches 2.48 wt% and 1.4 wt%, respectively, on proper experimental conditions, and the main phases of the master alloys are α-Al and Al 3 (Sc,Ti) phase. In the refined alloys, the average grain size can reach 27 μm, and the ultimate tensile strength and the elongation after fracture reaches 280 MPa and 35% in cast state, respectively. Compared to the pristine 6016 aluminium alloy, the significantly enhanced strength and good plasticity of the refined alloys contribute to the combined effects of grain refinement and precipitated phase strengthening. For the fracture of low doped alloys, originates from cleavage fracture mechanisms, and for the ones with high dosages, ductile fracture becomes dominant. [Display omitted] • A series of ternary Al-Ti-Sc master alloys were prepared by thermite reduction of Sc 2 O 3 and TiO 2. • The effects of technical factors on Sc and Ti contents were researched during the thermite reduction process. • The main second phase in Al-Ti-Sc master alloys is a well-matched Al 3 (Sc,Ti) solid-solution phase. • Both strength and plasticity of 6016-based alloys are improved significantly by addition of Al-Ti-Sc master alloys. • The strengthening mechanisms of the refined 6016-based alloys by Al-Ti-Sc master alloys were clarified. [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]

• Ti6Al4V/AA2024 alloy component is fabricated based on interweaving structure. • The compressive shear strength of the Ti6Al4V/AA2024 alloy component is 86.1 MPa. • The Ti6Al4V/AA2024 alloy component's shear strength is 79 % of as-deposited AA2024. • The fracture occurs in the interweaving layer in shear tests. The presence of brittle intermetallic compounds (IMCs) can easily lead to cracks at the interface of titanium/aluminum alloy components. A novel interweaving structure was proposed and a Ti6Al4V/AA2024 dissimilar alloy component was prepared. The interlocking between Ti6Al4V and AA2024 mitigates the adverse effects of brittle IMCs on the Ti/Al interface, while the interweaving of Ti6Al4V and AA2024 avoids the generation of continuous IMCs. The average compressive shear strength of the Ti6Al4V/AA2024 alloy component is 86.1 MPa, which is 79 % of that of as-deposited AA2024. The fracture occurred in the interweaving layer in shear tests. [ABSTRACT FROM AUTHOR]

We study the phase stability of the B2 phase in a two-phase Al 0. 5 NbTa 0. 8 Ti 1. 5 V 0. 2 Zr refractory high entropy alloy. We find that the ordered phase of this alloy primarily contains Zr, Al, and Ti, where Zr and Al occupy opposite sublattices. Although the site occupancy of Ti is not conclusive from the experiments, first-principles calculations confirm the preference of Ti atoms to occupy the Zr sublattice. We also find that the B2 phase composed of Al, Zr, and Ti is unstable and that it transforms into Zr 5 Al 4 Omega, L 1 0 , or an ordered hexagonal phase depending on strain and the presence of antisite defects. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mg-Gd master alloy has a significant modification effect on eutectic silicon of Al-Si alloy. • The mechanism of modification of eutectic Si by Mg-Gd master alloy is twin groove mechanism. • The 1.0wt.%Mg-Gd master alloy can improve the mechanical properties of Al-Si alloy. In this study, the modification of eutectic Si was carried out by adding Mg-Gd master alloy to Al-10Si aluminum alloy. The influence mechanism of Mg-Gd master alloy modification Si on the morphology, size and mechanical properties were studied. The results show that the Mg-Gd master alloy has a remarkable modification effect on eutectic Si, with the average length of eutectic silicon changing from 11.71 μm to 1.95 μm. A large number of twin bands appear in eutectic Si after modification, and the modification mechanism is mainly twin plane reentrant edges. After modification, the mechanical properties are improved significantly and the fracture mode is mainly quasi cleavage fracture. [ABSTRACT FROM AUTHOR]

• Area density could be reduced by explosively welding Mg to Al. • Impact causes delamination in the clad material with a thickness ratio of Mg: Al = 0.7: 0.3. • Compared to A6061-T6, clad material with a thickness ratio of Mg: Al = 0.5: 0.5 produces less forward ejecta. • Shielding performance can be enhanced by increasing the damage area in rear wall using Mg/Al clad material. In this study, we propose the use of a clad material, created from aluminum alloy A1100P-H24 and magnesium alloy AZ31B-H24 through explosive welding, as a Whipple shield for space applications. Two kinds clad materials with thickness ratios of Mg: Al = 0.5: 0.5 and Mg: Al = 0.7: 0.3 made from explosive welding, are compared to the current standard, the 1 mm thick A6061-T6 Whipple shield utilized in the international space station. By explosive welding low density, high specific strength, and high impact strength magnesium alloy with aluminum alloy, clad materials achieved 16.8% and 23.7% reduction in area density compared to A6061-T6. In the context of space debris mitigation, we performed hypervelocity impact tests on these clad materials. Detailed comparisons were made between the impact characteristics of the explosive welded clad materials and A6061-T6 by examining the perforation hole size and shape, and by collecting and analyzing the ejecta produced during impact. The experimental results revealed that the clad material with the thickness ratio of Mg: Al = 0.7: 0.3 experienced delamination at the material interface due to the penetration of projectile. On the other hand, the Mg: Al = 0.5: 0.5 clad material exhibited a perforation hole pattern comparable to that of monolithic aluminum and magnesium alloy materials. The cumulative number distribution of ejecta indicated that the clad material with a Mg: Al = 0.5: 0.5 ratio could reduce ejecta production. To further evaluate interface delamination, post-impact ultrasonic analyses were performed on the clad materials. [ABSTRACT FROM AUTHOR]

Titanium is a highly valued material. Developing a lower-cost titanium (Ti) metal powder production process, potentially substituting the conventional Kroll-HDH method, has challenged the titanium community for decades. The ease of aluminum forming alloys with titanium and the strong chemical affinity of titanium to oxygen rule out the possibility of fabricating pure Ti metal directly by aluminum reduction of TiO 2. Based on the demonstrated enhanced deoxidation of Ti using Mg metal, this paper proposes an Al–Mg combined stepwise reduction of TiO 2 to fabricate Ti metal powder. Critical challenges overcome in this research include predicting reaction thermodynamics and preparing Ti 2 O intermediate by Al reduction of TiO 2 without significant Al alloying, which is made possible by forming mild-acid soluble Ca 12 Al 14 O 32 Cl 2 byproduct. Various Al reduction conditions were investigated and optimized. To the best of our knowledge, it is the first report to fabricate Ti 2 O powder by Al reduction of TiO 2 with a highly stable chemical composition. The difficulty of sintering the Ti 2 O intermediate before Mg deoxidation to reduce the surface oxygen contribution is mitigated by mixing a certain amount of low-oxygen titanium powder with the Ti 2 O powder. This allows the densification temperature to be lowered from 1400 °C for sintering pure Ti 2 O powder to 1100 °C. Even with as much as around 15 wt% oxygen, the sintered powder can be effectively deoxidized by Mg with the help of hydrogen. A titanium metal powder with an oxygen content of 0.134 wt%, an Al content of 0.123 wt%, and other impurities meeting the standard of pure titanium metal powder (GB/T 34486-2017 FTA1) is successfully prepared by the Al reduction-Mg deoxidation combined process. It is a promising alternative for producing titanium metal powder and its derivatives. [Display omitted] • An Al-Mg combined stepwise reduction of TiO 2 to fabricate Ti metal powder is described. • A novel Al reduction-acid picking process helped by CaO and CaCl 2 was built. • Ti 2 O powder with a low Al content was successfully prepared by Al reduction of TiO 2. • A strategy to mitigate the difficulty of direct densification of Ti 2 O was achieved. [ABSTRACT FROM AUTHOR]

The buckling behaviour of combined shells fabricated from aluminium alloy and carbon fiber–reinforced polymer (CFRP) composites subjected to external hydrostatic pressure were investigated. Three sets of combined cylindrical shells with different combinations and one set of bare aluminium alloy cylindrical shells were designed and fabricated. The wall thickness of each cylindrical shell was measured. All the cylindrical shells were tested under external hydrostatic pressure, and the buckling load and final collapsed mode were recorded. Numerical models with real imperfections were established, linear and nonlinear analyses were performed to evaluate the buckling loads of cylindrical shells. The experimental and numerical results agreed favourably. On this basis, the effects of the thickness-diameter ratio, combination method and geometric imperfection on the buckling of combined cylinders were studied. This research can provide a reference for the design of combined shells made from CFRP and metal shell. • The geometry and buckling of 8 combined cylinders were tested. • The effects of the thickness-diameter ratio, combination method and geometric imperfection on the buckling of combined cylinders were discussed. • The failure mode of carbon fiber–reinforced polymer composite combined shell was discussed. • The numerical results are in good agreement with experimental results (within 8 %). [ABSTRACT FROM AUTHOR]

The effects of pre-soaking in seawater on the corrosion behaviour of the nickel aluminium bronze alloy were examined using electrochemical and erosion-corrosion tests. The surface passive film of the alloy pre-soaked for 30 d consisted of an outer loose CuO film, a middle dense Cu 2 O film, and a denser inner Cu 2 O film contained Al 2 O 3. The corrosion properties of the sample pre-soaked for 30 d were significantly improved, with ∼71% reduction in corrosion rate at 3 m/s compared with the unsoaked sample. Strong bonding between the substrate and passive films formed during pre-soaking effectively inhibited the entry of ions from seawater. • The pre-soaked sample surface corrosion film is divided into three layers. • The middle and inner layers are composed of dense Cu 2 O and thin Al 2 O 3 for protection. • The pre-soaked corrosion film has stronger adhesion to the substrate after erosion. • Significant improvement in erosion-corrosion performance of pre-soaked film sample. [ABSTRACT FROM AUTHOR]

• Barrier layer thinning of anodic films formed on aluminum alloys is a new challenge. • A simple barrier layer thinning step was studied after a single-step anodizing. • The thinning step was carried out in galvanodynamic mode with a constant scan rate. • Using an adequate rate, barrier layer thinning is controlled at the nanometric scale. • Barrier layer drilling opens the way for new post-treatments of functionalization. Thinning the barrier layer thickness of anodic films prepared on refined aluminum substrates (4 N or 5 N) was usually performed to elaborate -after the usual two-step anodizing method- anodic aluminum oxide (AAO) templates with pores opened at both sides, allowing the subsequent nanodevices synthesis. By contrast, there is a lack of studies concerning similar barrier layer thinning for anodic films grown -by a single-step anodizing - on commercial low alloyed aluminum substrates (1XXX series) or other more complex aluminum alloys (AA 2XXX-8XXX). Yet such a need is now emerging, particularly for future applications requiring transverse electrical conductivity of usual anodic films toward the aluminum alloy substrate. This work aims to study and to master a simple and cheap method for thinning the barrier layer thickness of such anodic films on commercial aluminum alloys. Here, the thinning is studied using a current density decrease (at a constant rate) after the anodic film growth in phosphoric acid-based electrolyte, using the conjunction of in-situ accurate electrochemical follow-up and ex-situ FE-SEM morphological observations. Variation of current density scan rate highlights that fast processes lead to no barrier layer thinning, and slow ones to the detachment of the whole oxide film. However, by choosing the right scan rate range, it is possible to successfully obtain, in a straightforward manner, anodic films still supported on aluminum alloy substrates, but with barrier layer thickness tuned at the nanoscale. [Display omitted] [ABSTRACT FROM AUTHOR]

• The static shear and fatigue performance of CFRP/aluminum alloy adhesive joint was studied. • The effect of size parameters on the mechanical property and failure behavior was clarified. • The fatigue failure mechanism of CFRP/aluminum alloy adhesive joint was revealed. The size parameter is quite significant for the performance of adhesive joint. In order to investigate the effect of size parameters on the mechanical property and failure behavior of CFRP/aluminum alloy single-lap adhesive joint, T300 CFRP laminate and AA5182 aluminum alloy sheet were bonded by Sika Power 497 structural adhesive under different size parameters. The quasi-static shear test and fatigue test were implemented, and the failure behavior and failure mechanism were analyzed. Results showed that the increase of aluminum alloy sheet thickness or bonding area length could effectively improve the bonding strength of adhesive joint, when the strength of the aluminum alloy sheet or the adhesive layer was insufficient. The shear failure modes of adhesive joint mainly included adhesive failure, base material failure and mixed failure. The fatigue failure modes of adhesive joint were mainly adhesive cohesion failure and adhesive adhesion failure. At low stress levels, the aluminum alloy sheet might fracture. In addition, this work can provide a scientific guidance for the engineering application of adhesive bonding technology. [ABSTRACT FROM AUTHOR]

Electron beam physical vapor deposition (EB-PVD) with high power axial EB guns has high deposition rates and therefore is well suited for depositing comparatively thick coatings with high throughput in mass production processes. The top sliding layer on bearing shells is a well-known use case for this technology. In low-cost manufacturing, often semi-finished products such as sheets or strips are coated, from which final products with a broad range of dimensions can be manufactured. The adaptation of related processes such as pretreatment and substrate cooling of three different semi-finished products was the focus of the investigations. All process steps were optimized for high throughput. Deposition with AlSn or AlSnCu alloys was carried out at coating rates up to 1 μm/s. These alloys, containing elements with different vapor pressures, were evaporated out of one continuously fed crucible with long-term stability. The deposited coatings have finely dispersed tin clusters in the aluminum matrix. The tin clusters have linear dimensions in the range of 200 to 400 nm. This size range is a direct consequence of the high coating rate; it is thus process-specific for EB-PVD. Such coatings are highly beneficial for applications such as plain bearings. Initial load tests have impressively confirmed the advantages for EB-PVD processed bearings. • Aluminum-tin alloys were deposited by EB-PVD at a static deposition rate of up to 1 μm/s. • The pretreatment process and substrate cooling have been optimized for high throughput. • The technology has been adapted to different types of semi-finished products: bearing shells, metal sheets, and strips. • The AlSn coatings have finely dispersed tin clusters with linear dimensions ranging from 200 to 400 nm. • Initial load tests showed a high load capacity of the manufactured bearings. [ABSTRACT FROM AUTHOR]

• The laser-cladded Cu-Ni-Cr alloy coating was prepared on aluminum alloy substrate. • The shear strength of Cu-Ni-Cr alloy coating is larger than the substrate. • The Cu-Ni-Cr alloy coating has excellent resistance to galvanic corrosion with TC4. The Cu-Ni-Cr alloy coating was prepared on 5083 aluminum alloy substrate using laser cladding technology. The microstructure of the coating and its galvanic corrosion resistance in contact with TC4 alloy were studied. The results indicate that the Cu-Ni-Cr alloy coating primarily consists of Al-rich dendrite phase and Cu-rich matrix phase. The shear strength of the Cu-Ni-Cr alloy coating is 154.68 MPa, which is greater than that of the aluminum alloy substrate. The galvanic current density of the TC4/Cu-Ni-Cr couple is 0.05 μA·cm−2. The neutral salt spray corrosion test results demonstrate that the Cu-Ni-Cr alloy coating exhibits excellent resistance to galvanic corrosion. The coating can attenuate the galvanic corrosion effect when it is in contact with the TC4 titanium alloy, offering new solutions to address the galvanic corrosion challenges between titanium alloy and aluminum alloy in marine environments. [ABSTRACT FROM AUTHOR]

• The joint quality of perforated CFRP and aluminum alloy stick-self-punch riveting was studied. • The static characteristics and the failure modes of the joint were analyzed. • Results showed that the main failure mode of HH-BR joint was laminate tearing. • The reasons why HH-BR joints have better performance than H-BR and SPR joints were explained. This paper explores the new hybrid hole-drilled bonding and self-piercing riveting (HH-BR) connection technique to enhance the strength and overall performance of carbon fiber reinforced polymer (CFRP) and dissimilar metal materials at joint interfaces. The forming quality, mechanical performance, failure modes, and fracture characteristics of the CFRP and aluminum alloy joints utilizing the HH-BR procedure were analyzed in detail and compared with the joints of the hole-less adhesive-bonding self-piercing riveting (H-BR) and self-piercing riveting (SPR). At the same time, the effects of different rivet performance levels, overlap lengths, and various fiber orientation angles on joint performance were discussed. The results show that joints made by the HH-BR technique have a substantial advantage in terms of achieving superior mechanical performance and interlocking value. Firstly, HH-BR joints with bent rivets and torn fibers have connection strengths that are noticeably higher than those with CFRP laminate delamination or rivet pullout failure. The use of the HH-BR technique for joining CFRP/aluminum alloy culminated in reduced strength loss and higher energy absorption than H-BR and SPR joints, improving the joint's overall strength. Secondly, the interlock value between the rivet and the plate, is what essentially determines the strength of HH-BR joints, especially evident in connections with 0°/90° fiber orientation and more overlap lengths. The results also show that there is a strong relationship between the height of the rivet head and the joint's mode of failure, and the height of the rivet head is affected by the rivet force. Furthermore, the interlock value's magnitude, the joint's remaining bottom thickness, and the metal material's capacity for plastic deformation are all directly correlated. [ABSTRACT FROM AUTHOR]

The pitting potential, intrinsic surface acidity, point of zero charge of passive film on Al are studied using first-principles calculations to establish their relationships. Influences of alloying elements Zn, Cr, Nb, Si, Mo and Sc on adsorption of NH 3 and NaCl, pH pzc of Al 2 O 3 and pitting susceptibility of Al are investigated. The efficiency for enhancing pitting resistance of Al is evaluated, yielding the ratios Si: Zn: Cr: Mo: Nb: Sc = 1.8: − 0.3: 1: 1.9: 1.4: 0.2. A model for the dependence of pitting potential on the concentration of alloying elements in Al alloy matrix is developed, based on effects of alloying elements on the surface charge of passive film. The effects of Sc on pitting potential and pH pzc of Al oxide are predicted based on the calculated results, which are supported by electrochemical measurement, XPS analysis and contact angle titration. • Correlations between pitting potential and surface acidity, pH pzc of passive film on Al alloy are proposed. • We develop a model for the linear dependence of pitting potential on alloying element contents in Al alloy matrix. • The efficiency for Zn, Cr, Nb, Si, Mo and Sc to enhance pitting resistance of Al alloy is theoretically predicted. [ABSTRACT FROM AUTHOR]

Many additively manufactured alloys exhibit higher strengths than compositionally identical alloys processed via conventional processing routes. However, this enhancement is not consistently observed in 7xxx series aluminum alloys. These alloys present two complications when printed via Laser Powder Bed Fusion (LPBF): significant evaporation of strengthening elements from the melt pool and hot cracking during solidification. To address these issues, we introduce two modifications to the feedstock powder: (i) we increase the concentration of alloying constituents to counteract evaporation during printing, and (ii) we disperse TiC nanoparticles within the feedstock powder to promote heterogeneous nucleation and limit grain growth, thus avoiding hot cracking and improving strength. Relationships between the evaporation of alloying elements and laser energy density are quantified experimentally using inductively-coupled-plasma mass-spectrometry and are well captured by simple analytical models. The microstructures in as-printed and heat-treated conditions are characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Printing parameters have been optimized to attain minimum porosity, resulting in tensile strengths up to 650 MPa, which are in good agreement with predictions from classic models of strengthening mechanisms. [ABSTRACT FROM AUTHOR]

Effects of neutron irradiation on the microstructure and mechanical properties of CMRR (China Mianyang Research Reactor) structural material pure aluminum and 6061 alloy were studied by scanning/transmission electron microscopy (S/TEM) and tensile tests. The fast neutron (E > 0.1 MeV) fluences of 1.09–2.89 × 1022 n•cm−2 produced damage doses of 1.6–4.2 displacements per atom (dpa). Voids and faulted 1/3<111> dislocation loops were observed in both pure aluminum and 6061 alloy. In particular, voids tended to preferentially aggregate on coarse Cu-rich and fine Mg 2 Si precipitates which contributes to the higher irradiation tolerance in terms of void formation for 6061 alloy, suggesting that the uniformly distributed precipitates can act as trapping sites for defect clusters during irradiation and thus promote recombination. The size and density of Mg 2 Si precipitates showed a slight increase and Cu-rich precipitates emerged in 6061 alloy after neutron irradiation. Moreover, radiation-induced segregation was also detected along the grain boundaries. After tensile testing, the pure aluminum showed a lower yield strength and larger uniform elongation than 6061 alloy, where a moderate uniform elongation was still reserved after irradiation to 4.2dpa. The severely reduced ductility in 6061 alloy is supposed to be caused by the transmutation product silicon which contributes to the increase of dispersed multiple precipitates after irradiation. Our results indicate that precipitates especially Mg 2 Si play a decisive role in void suppression, but are not suitable in diminishing the radiation hardening. [ABSTRACT FROM AUTHOR]

Nickel aluminium bronze alloy specimens were produced using laser powder bed fusion (LPBF) and subjected to heat treatment to understand their corrosion behaviour when exposed to a 3.5 wt% NaCl solution. Electrochemical analysis, including impedance spectroscopy and polarization curves, was performed to characterize the samples after 30 days of immersion. The findings reveal that the as-built samples exhibit superior corrosion resistance compared to the heat-treated samples, primarily attributed to the lower presence of intermetallic phases, which hinder the alloy's passivation process. • NAB produced via AM exhibit lower corrosion current densities than thr heat-treated. • The microstructure and corrosion behavior of NAB is significantly influenced by fabrication methods and heat treatment. [ABSTRACT FROM AUTHOR]

• Rapid preparation of porous graphite skeletons using selective laser sintering (SLS) molding technology. • Three-dimensional bicontinuous graphite/aluminum alloy composites were prepared using vacuum pressure casting. • The three modulations of flexural strength, thermal conductivity and thermal expansion coefficient of the composite are achieved by adjusting the volume fraction of porous graphite skeleton. • When the volume fraction of porous graphite skeleton is 55 %, the bending strength of three-dimensional bicontinuous graphite/aluminum alloy composite reaches 75.8 MPa, thermal conductivity (TC) reaches 116.84 W/m K, and coefficient of thermal expansion (CTE) reaches 6.11 × 10-6 K−1, which is expected to be a potential thermal management material. In this paper, porous graphite skeletons were rapidly prepared using selective laser sintering (SLS) molding technique. After several vacuum impregnation reinforcements, carbonization, graphitization and surface modification, the porous graphite skeleton has good compressive strength and thermal-physical properties. A356 aluminum alloy was compounded with porous graphite skeleton by vacuum extrusion casting method to obtain three-dimensional bicontinuous graphite/aluminum alloy composites. The effects of vacuum impregnation reinforcement on the comprehensive properties of the porous graphite skeleton were investigated, and the bending strength, thermal conductivity (TC) and coefficient of thermal expansion (CTE) of the three-dimensional bicontinuous graphite/aluminum alloy composites were regulated by changing the volume fraction of the porous graphite skeleton. In the composites, the porous graphite skeleton bonded well with the aluminum alloy interface. The various properties of the composites showed significant anisotropy of each by the influence of the porous graphite skeleton. When the volume fraction of porous graphite skeleton is 55 %, the bending strength of three-dimensional bicontinuous graphite/aluminum alloy composite reaches 75.8 MPa, TC reaches 116.84 W/m K, and CTE reaches 6.11 × 10-6 K−1, which is expected to be a potential thermal management material. [ABSTRACT FROM AUTHOR]

The mechanical properties and stress corrosion cracking (SCC) resistance of 7xxx series aluminium alloys are significantly affected by the composition and distribution of precipitates formed during heat treatment. In particular, their quench sensitivity is related to the formation of η-phase precipitates that nucleate heterogeneously on grain boundaries at lower cooling rates after solution treatment, which has been a key factor restricting the gauge of hot rolled plates in the aerospace industry. To better understand the effects of slower cooling rates on the composition of quench-induced grain boundary precipitates (Q-GBPs) found in thick plate 7xxx alloys, plasma focused ion beam and high-resolution scanning transmission electron microscopy were used to obtain accurate composition data. The η-phase Q-GBPs have a complex- branched morphology, which develops higher aspect ratios and secondary arms as the cooling rate is reduced. Only a small change in average composition of Q-GBPs was found with cooling rate; but a large scatter was observed. This is caused by significant Zn/Cu/Al composition gradients developing along their principal growth directions in both AA7050 and AA7085 alloys. This concentration gradient did not reduce significantly after a T76 treatment. Simulations of Q-GBP growth with different cooling rates using a CALPHAD-informed phase-field model, with the η-phase represented by a two-sublattice model, gave results consistent with experimental observations. Chemical gradients were predicted to develop in the Q-GBPs due to the changing local equilibrium at the growth front during the cooling. The influence of this non-homogeneous microchemistry on the SCC behaviour of 7xxx alloys is briefly discussed. [Display omitted] [ABSTRACT FROM AUTHOR]