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The high-energy ball milling process was applied to fabricate a composite material from 7075 aluminium alloy milling chips, silicon carbide, and titanium dioxide powders. Raw materials were ground, and the obtained powders were cold pressed and sintered. It was demonstrated that this method can be used in the recycling of aluminium alloy scrap characterised by a high surface-to-volume ratio, and also that chemical removal of the oxide layer from chips is not necessary. The finest particles, with 50 vol.% of their population below 36 μm, were obtained after grinding for 60 min at a 1000 rpm rotational speed. Such an intensive grinding was necessary to fabricate the compact composite material with a homogeneous microstructure and a low porosity of 0.7%. The corrosion resistance of the composites was studied in 3.5 wt.% NaCl solution using cyclic voltammetry and electrochemical impedance spectroscopy, and corrosion rates in the range of ca. 342 and 3 μA∙cm−2 were obtained. The corrosion mechanism includes aluminium alloy dissolution at the matrix/reinforcement interphase and around intermetallic particles localised within the matrix grains. [ABSTRACT FROM AUTHOR]

This study aims to modernize commonly preferred hybrid aluminum composites in the automotive and defense industries. For this purpose, Al-4Cu/B4C-SiC hybrid composites were manufactured using the hot pressing method and their microstructure, mechanical, and tribological properties were investigated. SEM/EDS analyses of the samples were conducted to examine morphological characteristics. Hardness, relative density, and three-point bending tests were performed on the produced samples. Additionally, wear tests were conducted under dry sliding conditions and different loads (5-10-15 N) to investigate tribological properties. The addition of hybrid reinforcements resulted in high hardness (88.54 HB) and relative density (98.83%) values. The highest bending stress (556.9 MPa) was observed in sample AC-4 (Al-4Cu/2B4C-2SiC). The lowest mass loss (1.1 × 10−3 g) was encountered in sample AC-6 (Al-4Cu/6B4C-6SiC), where all reinforcements were present together. Plastic deformation, oxidation, and residual wear mechanisms were identified on the worn surfaces of the samples. Consequently, the addition of hybrid reinforcements to Al-4Cu composites shows promising potential in enhancing the mechanical and tribological performance of the composites. [ABSTRACT FROM AUTHOR]

The new generation of hybrid aluminum matrix composite was targeted to meet the yearnings of advanced engineering application which it does through improved physical, mechanical, tribological, and microstructural properties. The performance of this composite depends on the reinforcing materials selected and combined, the processing technique adopted in synthesizing the hybrid composites and processing parameters selected during the composite synthesis. This study tends to review different types of eco-friendly materials combined with synthetic materials to synthesize this new generation of hybrid composites. Perhaps, their influence on the physical, mechanical, tribological, and microstructural behavior of the synthesized composites through stir casting technique. Furthermore, research areas which could further enhanced hybrid aluminum matrix composites production with suggested enhancement were looked into for future application in engineering sector. [ABSTRACT FROM AUTHOR]

The effects of different solution temperatures on the microstructure and corrosion resistance of graphene nanoplatelets reinforced A380 (A380-GNPs) composites were investigated. The results show that the grain size of the composites was significantly refined by adding 0.9 wt% GNPs, and most of the Si phases in the A380-0.9 GNPs composite after solution treatment at 505 °C were spheroidal. Energy dispersive spectroscopy analysis indicated that most of the Al2Cu phases have been dissolved into the matrix. The hardness of the 505 °C solution treated composites increased by 28.8% compared to the A380-0.9 GNPs composites. Immersion corrosion tests revealed that the corrosion rate of the 505 °C solution-treated A380-0.9 GNPs composites (46.76 μg cm−2 d−1) was 24.9% lower than that of the non-solution-treated (58.41 μg cm−2 d−1). Electrochemical analyses showed that the corrosion voltage of the 505 °C solution-treated composites (− 507.41 mV) was 7.4% higher than that of the non-solution-treated (− 548.76 mV). The 505 °C solution-treated A380-0.9 GNPs composites had a high surface-area ratio between the anodic phases (α-Al) and the cathodic phases (Al2Cu, Si), and the anodic corrosion current densities were relatively weak, which resulted in the best corrosion resistance. The refinement and uniform distribution of cathodic phases, such as Al2Cu and eutectic Si, inhibit the occurrence of micro-galvanic corrosion and also reduce the corrosion rate of the composites. [ABSTRACT FROM AUTHOR]

The present work aims to elucidate the mechanism of microstructural evolution in different regions of nano-SiC particles reinforced aluminum matrix composites prepared by friction stir processing (FSP) on its electrochemical behavior. Electron backscatter diffraction technique (EBSD) and transmission electron microscopy (TEM) were employed to characterize the microstructure evolution of stir zone (SZ), advancing side thermomechanically affected zone (AS-TMAZ), retreating side thermomechanically affected zone (RS-TMAZ) and base metal (BM). The electrochemical behaviors of the above zones were investigated using electrochemical tests. A homogeneous and fine microstructure is formed in SZ, not only the nano-SiC is homogeneously distributed within the grains with an average grain size of 3.5 μm, but also the recrystallized grains account for the highest percentage of 85 %. The potentiodynamic polarization curve indicates that the corrosion current densities of the BM, RS-TMAZ, AS-TMAZ and SZ are 0.89, 0.39, 0.85 and 0.36 μA/cm2, respectively, while the polarization impedances are 33.40, 51.42, 48.72 and 73.79 kΩ cm2, respectively. Combining the Nyquist and Bode plots analysis, the optimal electrochemical corrosion resistance is in SZ. The fine and homogeneous recrystallized grains in SZ significantly improve its electrochemical corrosion resistance. This is mainly ascribed to the increase in crystal defects as a result of the increase in grain boundaries, elevating the electron scattering. Simultaneously, the increase in high-energy state grain boundaries is beneficial to the rapid formation of a thicker passivation film. [ABSTRACT FROM AUTHOR]

In this work, fully densified Ni–SiC reinforced Ti6Al4V matrix composites were consolidated by pulsed electric current sintering (PECS) technique. The microstructural evolution and mechanical properties of the developed composites with varying SiC contents were investigated. The microstructural study revealed in-situ precipitation of TiC, Ti 5 Si 3 and Ti 3 SiC 2 strengthening phases within the composites. The α colony size in the composites was notably reduced compared to the fabricated SiC-deficient samples due to the addition of SiC additive into the Ti6Al4V alloy matrix. The in-situ precipitated phases enhanced the mechanical properties of the composites. Composite reinforced with 10 wt% SiC (TNi10SiC) displayed the highest hardness value of 609.8 ± 50.9 HV 0.5 among the sintered samples, translating to an increment of about 88 % compared to the unreinforced sample T. Among the sintered samples, the highest flexural strength of 2094.32 ± 97.67 MPa was obtained for the TNi5SiC composite, after which the flexural strength deteriorates with increasing SiC content as witnessed in TNi10SiC composite with the least flexural strength of 863.67 ± 71.57 MPa due to agglomeration of the reinforcement phases within the composite. Samples reinforced with 0 wt% SiC experienced a ductile fracture, and the composites containing 2.5 wt% - 5 wt% SiC content witnessed intergranular and interlamellar fractures. However, at higher SiC content, reinforcement pull-out and debonding of the agglomerated reinforcement phases predominates, and composites fail by brittle fracture. [ABSTRACT FROM AUTHOR]

Al6061 alloy has become prevalent in the industrial sector because of its low density, excellent machinability, and corrosion resistance but it lacks properties like hardness and wear. Therefore, surface modifications by friction stir processing (FSP) are done with additive nanosized particles like multi-walled carbon nanotubes (MWCNT), Titanium oxide (TiO2), and Graphene nanoparticles (GNP) To perform 2-pass FSP, a uniquely engineered fixture with coolant circulated underneath the plate at sub-zero temperatures is used. Grain refinement has been observed in micrographs as a consequence of 2-pass FSP. The coolant circulated beneath carries the heat generated and enhances the heat dispersion rate, culminating in finer grains. The calculated mean grain size of the Al6061 alloy was considerably decreased in all the surface composites. There is a substantial improvement in the microhardness profile, which has increased by nearly 70–90%, as well as a significant enhancement in tensile strength of almost 20–30% in all the composites. The ductile type of failure during tensile load is revealed by SEM fractography. The process of dynamic recrystallisation is responsible for the development of equiaxed grains. The wear resistance of all the composites is also enhanced, and the COF of Al6061/GNP composite is found to be lowest at 0.23. [ABSTRACT FROM AUTHOR]

Aerospace and automotive industries, among others, utilize reinforced aluminium metal matrix composite materials extensively. Aluminium alloy 5052 matrix was reinforced with tungsten carbide and titanium dioxide particulate reinforcements by varying their weight fractions, to fabricate the hybrid composites. The melt‐stir casting route was used to process the materials, and their characteristics were determined by measuring Vickers microhardness, tensile strength and peak elongation. The cost‐effectiveness and productivity of the melt‐stir casting route led to its selection. Investigations were carried out to assess how reinforcement particles were mixed into the aluminium alloy matrix using scanning electron microscopy and energy‐dispersive x‐ray analysis. The microstructure of aluminium alloy 5052 showed a distinct homogenous structural integrity. Adding tungsten carbide and titanium dioxide particles to aluminium alloy 5052 led to a 6.57 % rise in the Vickers microhardness value. The tensile strength of the hybrid composites made of aluminium, tungsten carbide, and titanium dioxide increased by as much as 8.7 %. The findings demonstrated that all of the hybrid composites failed due to particle fracture and ductile fracture in the case of the as‐cast aluminium alloy 5052. [ABSTRACT FROM AUTHOR]

Lightweight metal matrix composites made of aluminium are now essential in several fields, including aerospace and automotive. An important factor determining the quality and properties of the composite material is the ease or difficulty of evenly dispersing the reinforcement throughout the matrix. The goal of this research is to find out the impact of 40 and 90 µm varyingsized boron carbide (B4C) particles in A356 alloy composites. Using the liquid stir casting technique and K2TiF6 as the wetting flux, A356 alloy with 9 wt.% of B4C composites were prepared. SEM and EDS images were used to study the material's microstructure. ASTM-approved methods were used to measure the material's mechanical properties. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) confirmed that B4C particles were evenly distributed throughout the A356 alloy. The addition of B4C reinforcement to the A356 alloy matrix increased the hardness, ultimate, yield, compression, and impact strength of composites with a reinforcement size of 40 μm. The hardness of A356 alloy was enhanced by 40.7% and 34.6%, respectively, when 9 wt. % of 40 and 90 μm B4C were added. Similarly, there was a 34% increase in ultimate strength and a 31% improvement in yield strength. Both cases showed a little decrease in the ductility of the composites. Scanning electron micrographs were used to examine the morphologies of tensile fractured surfaces. [ABSTRACT FROM AUTHOR]

Abrupt advancement in technologies lead to growing thirst for efficient and economical alternative materials that possess superior properties. This lead to a gradual shift from the use of monolithic alloys to Metal Matrix Composites (MMCs). High resistance to corrosion and wear makes Aluminium MMC (AMMC) the most promising variant for structural, automotive, marine and aerospace applications. This review opens an insight into the current advancement of AMMCs, detailing an overview on diverse matrices and types of reinforcements that were used to produce such composites. This work also explores and classifies the gain and shortcomings of various phase formations during thermal treatment, revealing the possibilities of improving the physical strength and wear resistance with minimal complexity. This work also highlights the growing concern on corrosion performance of advance AMMC with ceramic reinforcements. In spite of the challenges involved in commercialising AMMC, recent trends of industrial utility reveal their potential to meet evolving demands. [ABSTRACT FROM AUTHOR]

The size and distribution of the silicon phase and intermetallic phase are important factors affecting the properties of Al11Si3Cu2NiMg alloy (M142). In this study, BNNS and micro-TiB2 were used to synergistically refine and reinforce M142 composites (M142-BNNS-TiB2). After T6 heat treatment, the comprehensive mechanical properties of M142-BN-TiB2 composites were excellent, with an ultimate tensile strength of 463 MPa and an elongation of 2.6%. In addition, the introduction of BNNS and micro-TiB2 changed the fracture mode of M142 from brittle fracture to quasi-cleavage fracture, and the introduction of BNNS and micro-TiB2 refined the Si phase and intermetallic phase, which could change the origin of the crack in the composite, thus improving the ductility of the composite. [ABSTRACT FROM AUTHOR]

In the present study, the densification behavior, microstructural evolution, mechanical properties, and friction behavior of a TiB2/Al8SiCu composite and Al8SiCu alloy manufactured by laser powder-bed fusion (PBF-LB) were systematically investigated. The results confirm that the addition of in situ TiB2 particles into Al8SiCu alloys reduce the volumetric energy density required for a high-density TiB2/Al8SiCu composite. The TiB2 particles promoted a transformation of columnar to equiaxed crystals and the formation of high-angle grain boundaries. The grains on the vertical direction of the PBF-LBed TiB2/Al8SiCu composite were much finer than those of the PBF-LBed Al8SiCu alloy. The addition of TiB2 promoted the grain refinement of the Al8SiCu alloy, of which the average grain size decreased from 15.31 μm to 7.34 μm. The yield strength (YS), ultimate tensile strength (UTS), and elongation (El) of the PBF-LBed Al8SiCu alloy were 296 ± 6 MPa, 517 ± 6 MPa, and 11.7 ± 1.0%, respectively. The PBF-LBed TiB2/Al8SiCu composite achieved a balance between strength and ductility with a yield strength of 328 ± 8 MPa, an ultimate tensile strength of 541 ± 3 MPa, and an elongation of 9.1 ± 0.7%. The increase in strength mainly resulted from grain boundary strengthening, dislocation strengthening, load-bearing strengthening, solid-solution strengthening, and Orowan strengthening, of which the dislocation strengthening and Orowan strengthening were critical. The enhanced hardness associated with the grain refinement and the formation of the in situ TiB2 particles also led to an enhanced tribological performance, of which reductions in the average friction coefficient from 0.655 to 0.580 and wear rate from 1.76 × 10−3 mm3/Nm to 1.38 × 10−3 mm3/Nm were found. [ABSTRACT FROM AUTHOR]

Flexoelectricity is often studied at the macroscopic scale for energy conversion and harvesting. The fact that microstructural heterogeneities can have a profound impact on a material's flexoelectric response has been under-appreciated and largely unexplored. To capture the effects of microstructure on both the macroscopic flexoelectric behavior and the development of microscopic electric field that drives such microscale processes, we develop a computational framework that enables the quantification of how the microstructure can influence the flexoelectric behavior of heterogeneous materials. The specific material evaluated is a porous composite of tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride polymer and aluminum (Al) particles. The models explicitly resolve the Al particles and voids within the microstructure. The focus of the analysis is on assessing the physical mechanisms that enhance the macroscopic flexoelectric output and determining the effective flexoelectric coefficient of the inhomogeneous material. The approach also allows the contributions of individual strain gradient components to the effective flexoelectric coefficient to be delineated and offers a method of determining the flexoelectric coefficients associated with individual strain gradient components using measurements of the macroscopic flexoelectric responses of microstructures with different concentrations of Al particles and voids. It is concluded that the enhancement of local strain gradients near the Al particles and voids and the activation of contributions from multiple strain gradient components are the primary mechanisms for the increase in the macroscopic flexoelectric output of the composites. The macroscopic flexoelectric coefficient under cantilever beam bending is found to rise linearly with the Al content, consistent with the experimental measurements. [ABSTRACT FROM AUTHOR]

To improve the microstructure of the Al/Mg composite fabricated by extrusion bonding, a novel method to achieve asymmetric extrusion of Al 7075/Mg EW75 composite is proposed, which uses an off-center setup of the initial billet and symmetric die. Good metallurgical bonding is achieved on the interface by the formation of the Mg23Al30 and Mg17Al12 phases as opposed to the Al3Mg2 and Mg17Al12 phases reported before. The asymmetric extrusion promotes recrystallization, refines the microstructure of the matrix, and weakens the strong basal texture of magnesium, which homogenizes the plastic deformation during loading and alleviates the stress concentration on the intermetallic layer. Asymmetric extrusion delays interface crack formation and improves tensile strength of the extruded composite. [ABSTRACT FROM AUTHOR]

In this study, Al6061 alloy matrix composites reinforced Al2O3-decorated reduced graphene oxide (Al2O3/RGO) with 0.1, 0.3 and 0.5 weight present (wt%) were successfully fabricated using high energy ball milling and hot extrusion techniques. The microstructures of these Al2O3/RGO/Al6061 aluminum matrix composites (Al MMCs) were characterized. The results showed that Al2O3/RGO were uniformly distributed within the Al6061 matrix and tightly bonded to the matrix. Al2O3 encapsulation on RGO surface would prevent the formation of Al4C3 brittle phase in matrix, ensuring that there was no reaction between the reinforcement and the matrix Al6061. Tensile strength and Vickers hardness tests demonstrated that the mechanical properties of Al MMCs significantly increased with addition of Al2O3/RGOs. Remarkably, Al MMCs with 0.1 wt% reinforcement showed tensile yield and tensile strengths of 270 MPa and 286 MPa, respectively, which were 49% and 43% higher than those of pure Al6061 prepared using the same process. Furthermore, the 0.1 wt% Al2O3/RGO composite also showed the best plastic deformation capability in considering of the strength. [ABSTRACT FROM AUTHOR]

The purpose of this work is to analyze the impact of reinforced Al2O3–LM6 aluminum composite made with dual mixed slurry for semi-solid casting with stirring, which is documented according to microstructure and wear properties. Under dry sliding pin-on-disk conditions, the composition and surface morphology of worn surfaces were carefully examined for the 10 N applied force, 1.2 m/s sliding speed, and sliding distances up to 750 m. Experimental findings indicate that Al2O3 reinforcement with semi-solid dual slurry effects give outstanding resistance against the adhesive wear. Microstructure, EDS, and XRD results from worn surface evaluation all show evidence of protective layers, which helps explain the reason for the rate of wear decreased due to processing. In this experiment, LM6 serves as the matrix material and Al2O3 as reinforcement. Al2O3–LM6 semi-solid cast composite was created via a dual mixed slurry technique with temperature control close to the solidus line for varying compositions. This work reports a substantial relationship between metallurgical and mechanical parameters. Mechanical properties and wear characteristics have been investigated. [ABSTRACT FROM AUTHOR]

Fabrication of aluminium (Al) composites by stir casting process is an effective method for fabrication of better quality of Metal Matrix Composites (MMCs). Stir casting technique is one of the most commonly accepted techniques. In this research work, al7075 / SiC+CeO2 hybrid MMCs have been fabricated with varying wt.% of SiC (2%, 4%, 6% and 8%) particulates and constant 5% of CeO2 particulates. The ascast alloy and hybrid composite were hot rolled at a temperature of 500°C. Whereas, both the ascast and hot rolled hybrid composite was subjected to micro-structural, mechanical and wear tests. Optical microscope analysis revealed uniform dispersal of hard particles with in the base matrix in case of both of ascast and hot rolled composites. Hot rolled MMCs showed enhancement of 22.64% of hardness when compared with ascast alloy with increasing reinforcement of 0-6 wt.% of SiC content. Tensile strength increases by 28.24% for hot rolled composites when compared to the as cast and other hybrid composites. Reduction of wear loss by 54.38% for hot rolled composites when compared to the as cast and other hybrid composites. A tensile and wear fractography result shows the internal fractured structure which was analysed using a SEM analysis. [ABSTRACT FROM AUTHOR]

This study investigates the impact of heat input, generated during friction stir welding, on the microstructure, mechanical properties, and corrosion resistance of dissimilar joints between A390-10 wt.% SiC composite and AA2024-T6 aluminum alloy. Welds were created using two rotational speeds: 600 rpm and 1600 rpm, while maintaining a constant traverse speed of 60 mm/min and employing a triangular pin tool. The results reveal that increasing the heat input from 125 to 354 J/mm leads to enhanced mixing in the stir zone, resulting in the formation of a layered structure. The stir zone area increases by 23% with the rise in heat input from 125 to 354 J/mm. Moreover, as the heat input and plastic strain in the stir zone increase, the particle size decreases by 31%, and their distribution becomes more uniform. Furthermore, an increase in heat input leads to the formation of coarser precipitates and particles on both the advancing and retreating sides, regardless of the type of precipitates formed. Conversely, reducing the heat input from 354 to 125 J/mm results in achieving maximum hardness (165.3 ± 2.3 HV0.1), yield strength (410.3 ± 11.3 MPa), ultimate tensile strength (514.5 ± 10.4 MPa), and minimum corrosion rate (0.41 mm/year). [ABSTRACT FROM AUTHOR]

The increased demand for lightweight structural materials in the transport sector has compelled researchers to develop materials with high strength and reduced structural weight, aiming to enhance vehicle performance, minimize fuel and oil consumption and reduce CO2 emissions. However, their structural weight and strength still need to be improved. Herein, an attempt has been made to fabricate aluminum-based composites reinforced with hexagonal boron nitride (h-BN: 1,3,5,7 wt%) and multi-walled carbon nanotubes (MWCNTs: 0.25, 0.5, 0.75, 1 wt%) through powder processing method. The results revealed that the 3BN/Al composite disclosed better densification (96.8%) and hardness (49 ± 1.5) among all BN/Al composites. Furthermore, the addition of 0.5 wt% CNTs to BN/Al composite significantly improved the densification (97.7%), Vickers hardness (106%) and tensile strength (189%) over pure Al. This improvement was attributed to homogeneously distributed h-BN and CNTs in the Al matrix and the formation of hard aluminum carbide (Al4C3) phase. The results demonstrate that BN/CNTs/Al composite exhibits superior mechanical strength, making them promising structural and functional materials for aerospace and automobile industries. [ABSTRACT FROM AUTHOR]

Efficiently joining TC4 and carbon fiber-reinforced aluminum matrix (Cf/Al) composite greatly expands the applications of composite in the aerospace industry. In this study, a liquid-solid infiltration extrusion (LSIE) process was proposed to effectively join Cf/Al composite with TC4 while preparing them. The microstructure, interfacial properties, and phase composition of the Ti-Cf/Al interface were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The mechanical response and failure modes of the composite were investigated. The results show that a TiAl3 intermetallic transition layer with a width of about 10 μm was successfully formed at the interface of TC4 and Cf/Al composite. Compared with the Cf/Al composite, the presence of this transition layer significantly increased the shear strength of the joint by 35.8 pct. In addition, through the unique deformation mechanism of the transition layer, the joint effectively disperses the stress concentration and delays the crack extension, thus realizing the transformation of the composite material from bending brittle fracture to multi-crack progressive damage mode. Meanwhile, the deformation behavior and strengthening mechanism of the TiAl3 transition layer on the composite are also deeply explored in this study. This successful and simple toughening strategy provides a feasible way to realize the application of continuous Cf/Al composite. [ABSTRACT FROM AUTHOR]

In this work, the high-temperature stable D023-Al3Zr was introduced to an Al-Cu-Ni-V alloy to improve the HT (350 °C) mechanical properties by the melt in situ reaction. The effect of Al3Zr contents and T6 heat treatment on the microstructure, room temperature, and high-temperature tensile properties of the Al3Zr/Al-6Cu-2Ni-0.5 V composites was investigated. The α-Al, Al2Cu, Al3Ni, Al3CuNi, Al7Cu4Ni, and Al3Zr phases were present in the as-cast composites. The amount of the fine (2-4 μm) blocky D023-Al3Zr increases with the increased addition of K2ZrF6 salt. After T6 heat treatment, the dispersed fine θ′-Al2Cu precipitates (200-300 nm) formed in the matrix. The interconnected structure of the Al3CuNi phase was broken, became spherical and coarsened. In addition, the Al3Zr particles had higher Cu content and changed from blocky to elliptical or spherical shapes without changing the tetragonal crystal structure after the T6 treatment. The highest HT tensile strength was observed for the as-cast composite containing 12 wt.%Al3Zr, reaching 118 MPa, 35.48% higher than the base alloy. After the T6 treatment, the tensile strength of 9 wt.%Al3Zr/Al-6Cu-2Ni-0.5 V composite at room and the elevated temperature reached 288.5 and 143.1 MPa, respectively. The analysis shows that the addition of K2ZrF6 not only introduced the high thermal stability D023-Al3Zr, but also promoted the precipitation and refinement of the θ′-Al2Cu after aging. The improvement of high-temperature mechanical properties of the composites is mainly attributed to the precipitation strengthening of the D023-Al3Zr phase and the dispersion strengthening by the θ′-Al2Cu phase that indirectly modifies by K2ZrF6. [ABSTRACT FROM AUTHOR]

Due to its lightweight, high strength, good machinability, and low cost, aluminum alloy has been widely used in fields such as aerospace, automotive, electronics, and construction. Traditional manufacturing processes for aluminum alloys often suffer from low material utilization, complex procedures, and long manufacturing cycles. Therefore, more and more scholars are turning their attention to the laser powder bed fusion (LPBF) process for aluminum alloys, which has the advantages of high material utilization, good formability for complex structures, and short manufacturing cycles. However, the widespread promotion and application of LPBF aluminum alloys still face challenges. The excellent printable ability, favorable mechanical performance, and low manufacturing cost are the main factors affecting the applicability of the LPBF process for aluminum alloys. This paper reviews the research status of traditional aluminum alloy processing and LPBF aluminum alloy and makes a comparison from various aspects such as microstructures, mechanical properties, application scenarios, and manufacturing costs. At present, the LPBF manufacturing cost for aluminum alloys is 2–120 times higher than that of traditional manufacturing methods, with the discrepancy depending on the complexity of the part. Therefore, it is necessary to promote the further development and application of aluminum alloy 3D printing technology from three aspects: the development of aluminum matrix composite materials reinforced with nanoceramic particles, the development of micro-alloyed aluminum alloy powders specially designed for LPBF, and the development of new technologies and equipment to reduce the manufacturing cost of LPBF aluminum alloy. [ABSTRACT FROM AUTHOR]

To use Al composites in structural applications, we need to improve strength and ductility at the same time. In this article, we explore three main concepts to solve this problem: improving the dispersion uniformity of CNTs in Al powder without damaging its structure by solution coating technique, fabricating a hybrid composite by reinforcing Al with nano-TiC-CNT, comparing the properties of nano-TiC-CNT and micron-TiC-CNT hybrid composites. Microstructure observation by SEM, TEM, and XRD revealed well-dispersed and preserved CNTs without the formation of a second phase. The Al-0.5CNT composite showed good tensile strength and elongation at break of 278 MPa and 14%, respectively. Further improvements in tensile strength and ductility of 285 MPa and 23%, respectively, were measured after the addition of 2.5 wt%; (1.4 vol%) TiC nanoparticles to Al-0.5CNT composite. However, the introduction of 2.5 wt-% TiC macroparticles only improved the tensile strength by 48% but elongation at break was up to 32%. The improved strength and ductility are attributed to the introduction of geometrical necessary dislocation and Orowan looping of dislocations leading to back stress strengthening. The new Al composite is expected to find application in automotive and aerospace component manufacture and thermal management. [ABSTRACT FROM AUTHOR]

In this study, SiC-reinforced aluminum matrix composites were powder metallurgically (PM) prepared and sintered using high-frequency induction system (HFIS). The samples with different ratios of SiC (wt.%10, 20 and 40) added to the aluminum matrix were sintered at 660, 800, and 1000 °C. In addition, Al/SiC composites were compared by sintering with the conventional sintering (CS) method under similar sintering conditions. The heating rate for the sintering process using HFIS was 500 °C/min, while the CS method used a heating rate of 10 °C/min. The effect of the temperature and SiC ratio on the density, hardness, phase structure, and microstructure of composites was investigated. The optimum sintering temperature was determined according to the SiC additive amount. When 10%, 20%, and 40% SiC by weight were added to the aluminum matrix in the sintering process with HFIS, the required sintering temperatures were determined as 660, 800, and 1000 °C, respectively. While new phases were not formed as a result of short-term HFIS sintering, a high-temperature Al4C3 phase was detected in CS sintering. HFIS sintered Al/SiC composite samples were obtained in Al and SiC phases with high density and hardness ranging from 43-118 HV. In the high-temperature sintering process with HFIS, the formation of Al4C3 was prevented and its physical and mechanical properties were improved. [ABSTRACT FROM AUTHOR]

The requirement for high-performance and energy-saving materials motivated the researchers to develop novel composite materials. This investigation focuses on utilizing aluminum alloy (A383) as the matrix material to produce hybrid metal matrix composites (HMMCs) incorporating boron carbide (B4C) and multi-walled carbon nanotube (MWCNT) through a cost-effective stir casting technique. The synthesis of HMMCs involved varying the weight fractions of B4C (2%, 4%, and 6%) and MWCNT (0.5%, 1%, and 1.5%). The metallographic study was carried out by field emission scanning electron microscopy (FESEM) mapped with EDS analysis. The results indicated a uniform dispersion and robust interfacial interaction between aluminum and the reinforced particles, significantly enhancing the mechanical properties. Micro-hardness and wear characteristics of the fabricated HMMCs were investigated using Vickers microhardness testing and the pin-on-disc tribometer setup. The disc is made of hardened chromium alloy EN 31 steel of hardness 62 HRC. The applied load was varied as 10N, 20N, 30N with a constant sliding speed of 1.5 m/s for different sliding distances. The micro-hardness value of composites reinforced with 1.5 wt% MWCNT and 6 wt% B4C improved by 61% compared to the base alloy. Additionally, the wear resistance of the composite material improved with increasing reinforcement content. Incorporating 1.5% CNT and 6% B4C as reinforcements results in the composite experiencing about a 40% reduction in wear loss compared to the unreinforced aluminum alloy matrix. Furthermore, the volumetric wear loss of the HMMCs was critically analyzed with respect to different applied loads and sliding distances. This research underscores the positive impact of varying the reinforcement content on the mechanical and wear properties of aluminum alloy-based hybrid metal matrix composites. [ABSTRACT FROM AUTHOR]

The mechanical properties of the aluminum matrix composite directly affect its application in aerospace, transportation, and other industries. In this study, the effect of TiB2 particles on the comprehensive properties which includes microstructure, thermal deformation behavior, tensile properties, fracture morphology and hardness of Al-Zn-Mg-Cu alloy was analyzed. Furthermore, the microstructures of these alloys were analyzed using energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and a metallography microscope. The stress–strain curves and dynamic softening of the two alloys were studied using the thermal compression test. Furthermore, a thermal processing diagram was constructed for comparing the safety and instability processing zones of the alloys. The Vickers hardness test and the tensile test were performed to compare their hardness, tensile properties, and fracture morphologies. The results demonstrated that TiB2 was contributing to the refinement of the grain size. When the deformation temperature and the stress–strain rate were 300–450 °C and 0.01–10 s−1, the alloy exhibited the same stress-strain variation trend during the thermal compression process before and after adding TiB2 particles. But the deformation resistance of the alloy was improved and processing instability zones were reduced from 300–320 °C/2.5–10 s−1 and 430–450 °C/0.2–0.5 s−1 to 420–450 °C/0.2–1 s−1 because of the addition of TiB2 particles. TiB2 particles could also increase the hardness of the alloy by 71.96% and improve the plastic properties and the fracture stress compared with before adding. [ABSTRACT FROM AUTHOR]

The poor mechanical and tribological properties limit the higher requirements of aluminum alloys in engineering and industrial applications, which leads to the rapid development of aluminum matrix composites (AMCs). Particulate reinforced AMCs have attracted extensive attention in automobile, electronics and military industries due to their low density, high strength, and excellent wear resistance. However, the interfacial reaction between reinforcements and the Al matrix tends to occur in conventional preparation processes owing to the higher reaction temperatures. The spark plasma sintering (SPS) technique is considered to be an efficient method for the fabrication of metal matrix composites, which can achieve rapid sintering, lower sintering temperatures, and higher densities than conventional fabrication processes. In addition, SPS can produce AMCs with excellent non-porous microstructure, fine grain size, and a strong bonding interface between reinforcement and Al matrix. Therefore, the interfacial reaction is effectively controlled and the structural integrity is maintained, resulting in enhanced strength and ductility. Based on the advantages of particulate reinforced AMCs and the SPS technique, the particulate reinforced AMCs fabricated by SPS have been extensively studied in recent decades, but have not been systematically evaluated. Therefore, this paper reviews the state-of-the-art particulate reinforced AMCs fabricated by SPS, focusing on the microstructure characterization, strengthening mechanisms, and mechanical and physical properties. Furthermore, the future research priorities and challenges of the high-performance particulate reinforced AMCs fabricated by SPS are also prospected. [ABSTRACT FROM AUTHOR]

A novel (8.5Al3BC + 14.5Al2O3)/Al composite was fabricated with exceptional elevated-temperature properties and stiffness. The composite boasts an average Young's modulus of 99 GPa, with ultimate tensile strength and elongation of the composite at 350°C averaging 188 MPa and 4.4%, respectively. The synergistic strengthening effect of Al3BC and γ-Al2O3 is responsible for the high-temperature properties, while they both contribute to the improvement of stiffness as they have a high initial Young's modulus. This innovative composite design holds promising potential for advancements in material engineering and performance optimization. This work reports a novel fabricated (8.5Al3BC + 14.5Al2O3)/Al composite with prominent elevated-temperature properties and stiffness and reveals the positive contribution of Al3BC and γ–Al2O3 particles to strength-ductility combination at high temperature. [ABSTRACT FROM AUTHOR]

Metal machining workshops generate a lot of metal chips, which pose both health and disposal challenges. Herein, for the first time, we demonstrate a novel process of reusing lathe-turning steel chips to manufacture high-compression strength Al alloy/steel composites. The process involves melting aluminium alloy onto the steel chips under vacuum and argon gas conditions. Clean and dried steel chips are packed inside a mould with a top layer of aluminium alloy pieces at three different quantity ratios of 80%Al/20% steel, 20%Al/80% steel and 50%Al/50% steel. The steel mould is then heated in a furnace at 650–700 °C until the aluminium metal melts. After a predetermined time of melting, argon gas is bubbled into the top layer (molten aluminium) of the mould while vacuum pumping is activated on the lower side of the mould (steel chips) for 5 min. The sample is allowed to cool within the mould. The composite containing 50%Al/50% steel has the highest mechanical properties with compression strength twice that of the other two samples. The microstructural observations revealed a good bonding between the steel chips and the Al alloy matrix. The study further presents the machinability of the samples, and it is seen that the composites behave like the aluminium matrix alloy during a turning operation and therefore do not require a special machining operation. It is shown that through this method, machining chips of steel can be recycled into high-compression strength metal–metal composites. These materials have the potential for high-compression strength applications such as machine supports and high-impact cushions. [ABSTRACT FROM AUTHOR]

Aluminum matrix reinforced with carbide powders is considered one of the best ways to improve abrasion resistance in pure alloys. Thus, this study aims to evaluate the abrasive wear resistance of A380 aluminum alloy reinforced with different amounts of NbC reinforcement. The A380 aluminum alloy was selected as the matrix and melted at a temperature of 750°C in an induction furnace. Three weight fractions of NbC powder (5 wt%, 10 wt%, and 15 wt%) and one without NbC were chosen as the reinforcement material and were added using the stir casting method at 400 rpm for 5 min. Mg acts as a bonding agent, Sr was used to modify the eutectic phase, and Al5Ti1B was a grain refiner. Three-body abrasive wear test was conducted in accordance with the ASTMG65 standard. The material properties were evaluated by hardness test, grain size determination, density, porosity, and metallographic analysis. The composite shows an increase in wear resistance and hardness as the NbC content was elevated, especially in the sample containing 15 % NbC. The worn surfaces showed a similar pattern with grooves and plowing, and the highest fraction of NbC (15%) had the lowest amount of plowing. [ABSTRACT FROM AUTHOR]

Keeping in view the structural applications of aluminum alloys, squeeze overcasting has been considered an attractive alternative to deal with the inherent casting defects at the interface region of bimetallic composites. Microstructure at the joint interfacial region highly depends on the casting parameters. For this reason, the current study has considered the most effective parameters including melt temperature, insert preheat temperature, squeeze pressure, pressure duration and time delay to fabricate the defect-free Al2026/Al–4.5%Cu composite. Besides this, the influence of aging treatment with 5%HCl solution quenching has been investigated on yield strength, ultimate tensile strength, percentage elongation and microhardness of interfacial region of the bimetallic joint. Results of the current study show that the melt temperature and squeeze pressure are the most influential parameters to boost mechanical properties. Metallographic analysis based on SEM shows that the optimum set of input parameters (MT = 800 °C, IT = 250 °C, SP = 100 MPa, PD = 150 s, TD = 10 s) offers the strong metallurgical bond between melt and solid insert without any inherent casting defects such as micro-cracks, gas porosity, pinholes, shrinkage voids and hot tearing. EDS analysis depicts that zinc coating is highly concentrated at the interfacial region which facilitates the formation of strong metallic bonding between distinct metals. [ABSTRACT FROM AUTHOR]

The microstructure and the mechanical properties of heat-treated thixoformed graphene-reinforced aluminium alloy composite Al–7.0 wt% Si–0.3 wt% Mg reinforced with graphene nanoplatelets (GNP) produced by thixoforming has been investigated. The fabricated composite was further subjected to conventional T6 and short T6 (ST6) heat treatment. The thixo-ST6 condition involved 1 h of solution treatment at 540 °C, followed by water quenching and 2 h of artificial ageing at 180 °C. Microstructural revealed the formation of well refined and spherodisation of eutectic Si phase with an average size when subjected to thixo-ST6 heat treatment, along with the presence of uniformly dispersed GNP particles during thixoforming, effectively inhibits the grain growth and recrystallisation. The thixo-ST6 heat-treated sample exhibited improved strength, with a maximum yield strength of 281 MPa and an ultimate tensile strength of 326 MPa, compared to the thixo-T6 sample which achieved 219 MPa and 239 MPa, respectively. The results suggest potential benefits for the automotive industry, where lightweight materials with improved strength are highly desirable. The combination of thixoforming and ST6 heat treatment can be considered as a promising approach for the production of high-performance aluminium alloy composites, particularly for automotive applications. [ABSTRACT FROM AUTHOR]

This research presents a novel approach to overcome the stress shielding effect and non-degradability commonly observed in metallic implants, which often require revision surgery. The study introduces a hybrid metal/ceramic (Ti/HA) reinforcement within the Mg-3Zn binary alloy matrix fabricated using the squeeze casting technique. The alloy matrix incorporates 1 wt% Ti and varying weight percentages (0.5, 1, and 1.5 wt%) of hydroxyapatite (HA). Microstructure analysis revealed significant grain refinement in the alloy upon adding the hybrid reinforcement. Phase analysis using XRD confirmed the presence of Mg-Zn intermetallic phases and corresponding reinforcement phases. Vickers microhardness testing demonstrated a 14.4% (89 HV) increase in hardness for the hybrid composite with 1Ti/1.5HA compared to the unreinforced alloy and other composites. Compressive testing revealed enhanced mechanical properties in the hybrid composites. The 1Ti/1.5 HA hybrid composite displayed a 12% (121 MPa) increase in compressive yield strength (CYS) compared to the alloy, while the 1Ti/1HA hybrid composite exhibited an impressive 22.5% (217 MPa) increment in compressive strength. Corrosion performance evaluation in a phosphate-buffered saline (PBS) environment indicated that the 1Ti/1.5 HA hybrid composites demonstrated comparable corrosion performance to the unreinforced alloy, with a corrosion density of 4.53 × 10−5 μA/cm2 and a linear polarization resistance of 893 ohms. Based on the findings, the Mg-3Zn alloy with 1Ti/1.5 HA hybrid reinforcement emerges as a promising material for load-bearing biodegradable implants. [ABSTRACT FROM AUTHOR]

The performance of industrial tribo-systems depends on advanced composites with superior tribological characteristics. In this study, the CoCrFeMnNi high entropy alloy (HEA) is prepared through mechanical alloying, while stir squeeze casting aided with an ultrasonic transducer is used to fabricate AA 6082 alloy and x% HEA/AA composites (where, x= 2, 4, 6, 8 in weight percentage). The effect of HEAp on dry sliding wear performance of HEA/AA composites is examined in as-cast conditions using a pin-on-disk wear tester at varying normal applied pressure (0.254 MPa, 0.509 MPa, 0.763 MPa, 1.018 MPa, and 1.273 MPa), varying sliding distance (1000 m, 2000 m, 3000 m, 4000 m, and 5000 m) and a constant sliding speed (3.5 m/sec), special emphasis is centered on response factors such as wear rate, seizure resistance, and bulk temperature upsurge. The composite showed an ability to withstand higher temperatures, and better seizure and wear resistance over the alloy. The phase identification and microstructural study were carried out using an X-ray diffractometer, field emission scanning electron microscope, and transmission electron microscope, whereas the topography of worn-out surface was examined through an optical profilometer. There was a substantial decrease in coefficient of friction, and wear rate noticed as the HEAs concentration increased, whereas in all the wear conditions, the wear rate of 8% HEA/AA composite shows maximum resilience against wear, the inclusion of HEA particles also influences the extent of the subsurface at the seizure condition. [ABSTRACT FROM AUTHOR]

The effect of different Cu contents (0~5%) on the microstructure and mechanical properties of 15wt.%Mg2Si/Al-La composite was investigated in the present work. The results show that Cu addition had a refining effect on the primary Mg2Si particles. The smallest particle size was acquired when 2% Cu was added. The UTS exhibited a parabolic tendency, which increased from 173 MPa to 227 MP by 31.21% and then decreased with further increasing Cu content. The UTS enhancement could be attributed to the appropriate content of Cu (2%) addition, which led to the formation of Cu-rich phases. When the Cu content was further increased, the UTS of the composite decreased for the coarsening of the Mg2Si particles and the increasing fraction of hard brittle phases. [ABSTRACT FROM AUTHOR]

When processed conventionally, aluminum-bronze alloys with high mechanical strength require machining after the raw state of fusion, and the waste (chips), if not reused, can cause problems for the environment and costs for the company. Therefore, this article proposes an alternative for recycling aluminum bronze through the new route via Powder Metallurgy (PM), analyzing the resulting microstructure. This study compares the microstructures of the aluminum bronze derived from extraction (the samples received - SR) and the state after the powder metallurgy (PM) process with the addition of vanadium carbides (VC). The study also analyzes the distribution of VC in the microstructure of the PM composite as well as the influence of the TQ30 heat treatment on this composite. For the PM process, aluminum alloy and bronze chips were ground together with vanadium carbide (VC) in a high-energy mill for 50 hours. The powders obtained were pressed uniaxially (400 MPa) to achieve good compaction. The samples were then sintered (900°C/1h), water quenched (900°C/2h), and subjected to treatment according to the TQ30 standard, which, in addition to the previous treatments, also includes tempering at 500°C for 2 hours (ASTM B150/B150M-12 standard). The microstructure observed in the SR samples was martensitic (in needles), with secondary phases dispersed in the matrix. On the other hand, the microstructure of the PM samples showed equiaxed grains of the alpha phase (κ), as well as the secondary phases kapa (κ) and beta line (β'), in contrast to the needle-shaped microstructure of the conventional melting process. [ABSTRACT FROM AUTHOR]

Given the characteristics of a thick steel/aluminum composite plate, such as its large thickness and the significant differences between its components, it is difficult to prepare using direct rolling. Instead, a thick steel/coating/aluminum composite plate may be successfully prepared by combining supersonic flame coating technology with a hot rolling composite process. In this study, the interface shear strength test, SEM, EDS, and other detection methods were applied to investigate the effects of the reduction rate and coating thickness on the interface structure and mechanical properties. The results show that under the condition of single-pass direct rolling, the micro-interface of steel/aluminum is improved with an increase in the reduction rate, but the bonding strength of the interface remains poor. After adding the coating, the thickness of the diffusion layer and the shear strength increase significantly. When the coating thickness is reduced to 0.1 mm, the deformation coordination and shear strength of the composite plate are further enhanced under the combined action of mechanical interlocking and metallurgical bonding. The tensile shear fracture is mainly located at the steel/coating interface. The interfacial shear strength reaches 66 MPa, which exceeds the requirements of the US military standard MIL-J-24445A (SH) for steel/aluminum shear strength. The research results thus support the use of this new method for the simple and efficient production of thick steel/aluminum composite plates. [ABSTRACT FROM AUTHOR]

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs. [ABSTRACT FROM AUTHOR]

In this paper, a brake cylinder coating comprising a composite material of an Fe3Al and Cr3C2 mixed powder was prepared by adding laser cladding onto carbon structural steel. We studied the influence of process parameters on the microstructure and tribological properties of the cladding materials using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and 3D white light interferometer and wear tests. The influence of different processes on the morphology of the carbide strengthening phase was found to be relatively small with a Cr3C2 content of 15 wt.%. The carbides mainly exhibited a network structure in each group of cladding layers. The area of the network strengthening phase varied under different processes. Of the cladding layers formed with different processes, the scanning speed of the 0.003 m/s cladding layer had the lowest wear rate. When the laser power was too low or the powder feed rate was too high, unmelted Cr3C2 particles could be found in the cladding layer. During the wear process, the particles peeled off, causing severe abrasive wear. When the powder feeding rate was too low, more materials in the base material entered the cladding layer. This made the composition of the cladding layer similar to that of the grinding material, resulting in severe adhesive wear. [ABSTRACT FROM AUTHOR]

In the semiconductor manufacturing process, when conducting inductively coupled plasma-reactive ion etching in challenging environments, both wafers and the ceramic components comprising the chamber's interior can be influenced by plasma attack. When ceramic components are exposed to long-term plasma environments, the eroded components must be replaced. Furthermore, non-volatile reactants can form and settle on semiconductor chips, acting as contaminants and reducing semiconductor production yield. Therefore, for semiconductor processing equipment parts to be utilized, it is necessary that they exhibit minimized generation of contaminant particles and not deviate significantly from the composition of conventionally used Al2O3 and Y2O3; part must also last long in various physicochemical etching environment. Herein, we investigate the plasma etching behavior of Y2O3–Y4Al2O9 (YAM) composites with a variety of mixing ratios under different gas fraction conditions. The investigation revealed that the etching rates and changes in surface roughness for these materials were significantly less than those of Y2O3 materials subjected to both chemical and physical etching. Microstructure analysis was conducted to demonstrate the minimization of crater formation. Mechanical properties of the composite were also analyzed. The results show that the composite can be commercialized as next-generation ceramic component in semiconductor processing equipment applications. [ABSTRACT FROM AUTHOR]

The microstructure and compressive properties of the 7xxx series aluminum alloy (Al – 12.44Zn – 3.22Mg – 1.13Cu – 0.19Zr – 0.12Sr) reinforced with SiC whiskers via squeeze casting are investigated after aging treatments T6-1, T6-2, T6I4-1, and T6I4-2. For this purpose, the effect of four kinds of aging heat treatments on the properties of the aluminum metal matrix composites (AMMCs) is studied systematically through Vickers hardness and room temperature compressive testing. The microstructure is analyzed by optical microscopy, scanning electron microscopy, and x-ray diffraction. The experimental results show that the hardness of the AMMCs after four kinds of aging processes has different degrees of improvement compared to no-aging. After the T6-1, T6-2, T6I4-1, and T6I4-2 aging processes, the hardness of the composites is 325, 278, 306, and 345.8 HV, respectively. The additional T6-2 aging treatment provides the highest compressive strength and compressive strain, about 747 MPa and 7%, respectively, as well as a maximum dislocation strengthening of approximately 86.89 MPa. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are considered ideal nanoscale reinforcement for the development of high-performance metal matrix composites due to their unique structure and excellent mechanical properties. However, CNTs are easy to agglomerate and have poor wettability with the aluminum matrix, resulting in unsatisfactory effects when added to the aluminum melt. In this study, Cu-coated carbon nanotubes (Cu@CNTs)-reinforced aluminum matrix composites were fabricated by high-energy ultrasonic-assisted casting. Moreover, the effects of different Cu@CNTs content on the microstructure and mechanical properties of aluminum matrix composites were explored. Meanwhile, Fluent 19.0 software was used to further explore the function of ultrasonic vibration in the melt. The results demonstrated that the mechanical properties of composite with 1.2 wt% Cu@CNTs are optimal. Compared with the matrix, the composite with 1.2 wt% Cu@CNTs displayed a 39.3% increase in yield strength, 53.5% increase in ultimate tensile strength, and 5.7% increase in elongation. The simulation results showed that the uniform dispersion of Cu@CNTs and grain refinement can be attributed to the acoustic streaming effect and cavitation effect of high-energy ultrasound. The improvement of the properties of the composites can be attributed to the grain refinement and the load-bearing effect of CNTs. [ABSTRACT FROM AUTHOR]

Al-Cu-Fe-Ce quasicrystalline-reinforced 6061 aluminum matrix composites were prepared through hot press sintering and treated with a solid solution and aging treatments. The influence of the solid solution and aging treatments on the microstructure and mechanical properties of the composites was investigated by XRD, EDS, SEM, and TEM. The results show that using Al-Cu-Fe-Ce quasicrystalline intermediate alloy as the reinforcing phase increases the interfacial areas of the composites and enhances the grain boundary strengthening effect, which is conducive to the improvement of the mechanical properties of the composites. And through the solid solution and aging treatment, the β phase and the Al2CuMg phase belonging to the orthorhombic crystal system, as well as the β″ phase and a small amount of the β′ precipitated phase, were formed in aluminum matrix composites, and these precipitated phases all existed in the composites in a fine and uniform distribution, which ensured the consistency of the mechanical properties of the materials and improved the mechanical properties of the composites. Meanwhile, the deficiency of quasicrystalline particle-reinforced 6061 aluminum matrix composites in age-hardening was solved and the age-hardening capability of the composites was further developed. This method provides a feasible process route for the preparation of high-performance aluminum matrix composites. The application of this process is expected to improve the mechanical properties and durability of this composite and offer a more reliable option for the application of aluminum matrix composites in aerospace, transportation, and other fields. [ABSTRACT FROM AUTHOR]

In this paper, a series of AlN–Al nanocomposite films are prepared by reactive magnetron sputtering. The effects of N 2 flow rate on the microstructure and mechanical properties of the films are studied. The formation and evolution mechanism of the nanocomposite structure are revealed. The results show that with the decrease of N 2 flow rate, the microstructure goes through three stages: pure AlN, amorphous Al surrounded nanocrystalline AlN and AlN nanoparticle reinforced Al matrix composite. Benefiting from the good wettability of Al on AlN ceramics, the film deposited at 6 sccm N 2 flow rate forms a nanocomposite structure of about 8 nm AlN grains wrapped by 1–2 nm amorphous Al. The hardness of the films increases first and then decreases with the decrease of N 2 flow rate, ranging from 4 GPa to 25 GPa. The toughness of the films is analyzed by the ratio of H/E, H3/E2, the normalized plastic depth (δ H) and the morphology of large load indentation. The results show that the toughness of the nanocomposite film obtained at 6 sccm N 2 flow rate is significantly improved while maintaining the hardness equivalent to that of pure AlN film. The improvement in toughness comes from the microcracks initiated in AlN hindered by the surrounding Al phase. [ABSTRACT FROM AUTHOR]

Al-x%Al2O3 composite protective coatings were prepared on the surface of LA43M Mg-Li alloy substrate by cold-spraying technology. The microstructure, corrosion resistance, tribological properties of the coatings were investigated in detail. The results showed that the addition of hard Al2O3 particles was conducive to the deposition of Al-based coating, and the bonding mode between Al-x%Al2O3 coating and substrate was metallurgical bonding and mechanical interlocking. Moreover, the addition of Al2O3 particles was beneficial for increasing the density of the coating, and significantly improving the corrosion resistance, hardness and tribological properties of composite coatings. Respecting the corrosion resistance of Al-x%Al2O3 composite coatings, the electrode potential of coatings increased significantly and stabilized to about − 1.0 V when the additive amount of Al2O3 increased to 10-25%, while the corrosion current density decreased to about 10-8 A/cm2, which was four orders of magnitude lower than that of LA43M Mg-Li alloy substrate. On the other hand, the tribological properties of Al- x%Al2O3 composite coatings were improved with the additive amount of Al2O3 phase increased. When the additive amount of Al2O3 increased to 15-25%, the coefficient of friction was stable at about 0.45 and the wear rate decreased. [ABSTRACT FROM AUTHOR]

Novel Ti/Al laminated composite embedded with particles of the high entropy alloy Al0.5CoCrFeNi were produced by vacuum hot press sintering at 650°C. The microstructure of the laminated composite was investigated using XRD, SEM, EDS, TEM and EBSD techniques. It was found that a thin layer of Al3Ti was formed at the Ti/Al interface. There were no obvious defects between the Al0.5CoCrFeNi particles and Al matrix, achieving a good interfacial bond. The tensile properties of the material were tested at room temperature. The results of the tensile test indicated that the material exhibited an elongation to failure of 59% and an average tensile strength of 240 MPa, demonstrating excellent plastic deformation capability. During the tensile process, the expansion of fractures and cracks in Al0.5CoCrFeNi particles can consume energy, which helps to improve the material's ability to undergo plastic deformation. Based on the morphologies of tensile fracture, it has been observed that the fracture surface of high entropy alloys exhibits a mixed fracture mode consisting of both brittle and plastic fracture. The brittle BCC phase has been identified as the main cause of cracking in HEA. Ultimately, the material fractures due to necking. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) reinforced by 5 wt% B4C particles were fabricated by direct laser deposition (DLD) technology. The phase composition, microstructure, and microhardness of the B4C/aluminum matrix composites (B4C/AMCs) were analyzed by OM, XRD, SEM, TEM, EBSD, microhardness test and molecular dynamics simulation (MD) in detail. The results show that acicular microstructure of AlB12 and Al4C3 are formed in the B4C/AMCs fabricated by DLD. With the addition of B4C, the crystallographic orientation of AMCs changes from (001) texture to random orientation distribution, and the microhardness increases by about 65%. During the DLD process, boron atoms and carbon atoms are released by B4C decomposition instead of diffusing through the solid–liquid interface between Al and B4C, and they react with the liquid Al to produce AlB12 and Al4C3 in the molten pool. Moreover, B and C atoms distribute along a strip orientation in the molten pool, which may be retained after the cooling to form the acicular microstructures. This work demonstrates the possibility and good prospects of obtaining AMCs reinforced with B4C, AlB12 and Al4C3 phases by the DLD technique and provides new insights into the microstructural evolution of the composites. [ABSTRACT FROM AUTHOR]

In the present study, the Al7075 metal matrix composite was reinforced with different weight percentages (HEA content 0–8 wt%; interval of 2) of CoMoMnNiV high entropy alloy (HEA) was processed by an ultrasonic vibrator-coupled stir casting route. The mechanical alloying technique was employed to prepare high-entropy alloy metallic powder. The developed composite was examined for microstructural and mechanical behaviour. The phase evolution and microstructure of HEA particles and composites were examined by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. An optical microscopic examination was carried out to investigate grain size and reinforcement dispersion over the matrix materials. The mechanical properties of composites improved significantly with HEAp content and attained maximum value for a composite with 6 wt% HEAp content. The hardness and ultimate tensile strength of the 6 wt% HEAp composite improved by 40% and 53%, respectively, as compared with as-cast Al7075 alloy. [ABSTRACT FROM AUTHOR]