Particle-reinforced Aluminum Research Articles

EVALUATION OF PHYSICAL AND MECHANICAL PROPERTIES OF BN REINFORCED AL7079 METAL MATRIX COMPOSITES

Metal matrix composites (MMCs) are regarded as viable alternatives to conventional materials such as metals, plastics, and ceramics in structural applications due to their properties, including lightweight, high specific stiffness, elevated elastic modulus, enhanced specific strength, and excellent wear resistance. Among the many metal composites, aluminum metal matrix composites (MMCs) have emerged as sophisticated engineering materials for several prospective applications in engineering industries due to their superior qualities compared to typical aluminum alloys. Ceramic particles are the most extensively utilized reinforcements in MMCs due to their superior wear resistance, thermal stability, and exceptional bonding with the matrix. This research work has been conducted to develop ceramic particle-reinforced aluminum matrix composites and to evaluate their physical and mechanical properties. Al7079 alloy and Boron Nitride (BN) are selected as the matrix and reinforcement for the study respectively. The stir casting technique was utilized to fabricate the composites.Al7079-BN composites are prepared by varying the percentage of BN reinforcement particles from 0 to 8% by volume, with an increment of 2%. Test specimens were machined from the produced composites for the evaluation of microstructural, physical, mechanical properties according to ASTM standards. The microstructural analysis of the produced samples was conducted using scanning electron microscopy (SEM). The density of the composite was assessed empirically using Archimedes principle and theoretically through the rule of mixture. Microstructural analysis reveals a homogeneous distribution of BN particles throughout the matrix without any agglomeration, and it also demonstrates excellent bonding. The density of the composites decreased by approximately 4.6% with the incorporation of BN reinforcement up to 8%, attributed to the lower density of BN particles. The mechanical properties such as hardness, tensile strength, Youngs modulus, and compressive strength of the composite increases significantly.

Effect of rotational speed on friction stir welding microstructure and properties of cast and rolled (ZrB2 + Al3Zr) particle-reinforced aluminum matrix composites

Effect of rotational speed on friction stir welding microstructure and properties of cast and rolled (ZrB2 + Al3Zr) particle-reinforced aluminum matrix composites

Study on the Critical Conditions for Ductile-brittle Transition in Ultrasonic-assisted Grinding of SiC Particle-reinforced Al-MMCs

High volume fraction (45 %) silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al-MMCs) play a significant role in various engineering fields due to their outstanding performance. However, damages characterized by SiC particle fracture during machining lead to poor surface integrity, which severely affects the fatigue performance of SiCp/Al composite structural components. Ultrasonic-assisted grinding (UAG) is acknowledged as beneficial for promoting ductile grinding in hard and brittle materials. This study focuses on the critical conditions for ductile-brittle transition in ultrasonic-assisted grinding of SiCp/Al composites and develops a mechanism and data driven model of critical undeformed chip thickness (UCT) for ductile grinding to accurately predict the material removal mode. The model thoroughly integrates considerations of chip morphology, removal mode transition mechanism, and grinding surface damage characteristics. Response surface methodology (RSM) and genetic algorithms (GA) were utilized to correct the impact of processing parameters on the removal regime. Experiments on ultrasonic-assisted side and end grinding were conducted to thoroughly discuss the effects of different undeformed chip thicknesses, grinding speeds and ultrasonic vibration amplitude on surface damage and the critical conditions for the ductile-brittle transition. The findings corroborate the experimental data with the predicted values. Ultrasonic vibration can effectively reduce the brittle fracture of SiC particles in SiCp/Al composites. Appropriately increasing the grinding speed and reducing the chip thickness can enhance the critical chip thickness for ductile grinding and decrease the proportion of brittle surfaces, thereby achieving a balance between surface integrity and grinding efficiency. This research provides guidance for high-performance machining of SiCp/Al composites.

Optimization of Tool Wear and Cutting Parameters in SCCO2-MQL Ultrasonic Vibration Milling of SiCp/Al Composites

Silicon carbide particle-reinforced aluminum matrix (SiCp/Al) composites are significant lightweight metal matrix composites extensively utilized in precision instruments and aerospace sectors. Nevertheless, the inclusion of rigid SiC particles exacerbates tool wear in mechanical machining, resulting in a decline in the quality of surface finishes. This work undertakes a comprehensive investigation into the problem of tool wear in SiCp/Al composite materials throughout the machining process. Initially, a comprehensive investigation was conducted to analyze the effects of cutting velocity vc, feed per tooth fz, milling depth ap, and milling width ae on tool wear during high-speed milling under SCCO2-MQL (Supercritical Carbon Dioxide Minimum Quantity Lubrication) ultrasonic vibration conditions. The results show that under the condition of SCCO2-MQL ultrasonic vibration, proper control of milling parameters can significantly reduce tool wear, extend tool service life, improve machining quality, and effectively reduce blade breakage and spalling damage to the tool, reduce abrasive wear and adhesive wear, and thus significantly improve the durability of the tool. Furthermore, a prediction model for tool wear was developed by employing the orthogonal test method and multiple linear regression. The model’s relevance and accuracy were confirmed using F-tests and t-tests. The results show that the model can effectively predict tool wear, among which cutting velocity vc and feed rate fz are the key parameters affecting the prediction accuracy. Finally, a genetic algorithm was used to optimize the milling parameters, and the optimal parameter combination (vc = 60.00 m/min, fz = 0.08 mm/z, ap = 0.20 mm) was determined, and the optimized milling parameters were tested. Empirical findings suggest that the careful selection of milling parameters can significantly mitigate tool wear, extend the lifespan of the tool, and enhance the quality of the surface. This work serves as a significant point of reference for the processing of SiCp/Al composite materials.

Evolution process of T1 precipitate in Al–Cu–Li–TiC/TiB2 alloy during aging treatment

In this study, particle-reinforced aluminium matrix composites (PRAMCs) of an Al–Cu–Li alloy were prepared using nano-sized TiB₂+TiC particles. The relationship between TiB₂+TiC nanoparticles and T1 precipitates during the ageing process, as well as the influence of TiC + TiB₂ particles on the growth process of T1 precipitates during the ageing process, were investigated. The grain sizes of the A0 and A1 samples were found to be 249.89 μm and 86.42 μm, respectively. The dislocation density is greater in the deformed A1 sample. The coefficient of thermal expansion (CTE) effect generated by TiC and TiB₂ particles stimulates the precipitation process of T1 precipitates. The A1 alloy reached the peak ageing state in a shorter time and yielded a greater number of T1 precipitates. The precipitation process of T1 precipitate is: SSSS→T1P→T1. The transition from T1P (face-centered cubic, FCC) to T1 (hexagonal close packing, HCP) entails a modification in the order of packing. The recently formed T1P precipitate is attached to the established T1 precipitate and extends along the c-axis through the shared copper-rich layer that has formed on both sides of the mature T1 precipitate. The mechanical properties of sample A1 are optimal at T = 22h, with a yield strength, tensile strength, and elongation of 520 MPa, 553 MPa, and 8.2%, respectively. In comparison to the A0 sample, the yield strength and tensile strength exhibited an increase of 5.05% and 5.13%, respectively.

The influences of nanoparticles on the microstructure evolution mechanism and mechanical properties of laser welded stainless steel/aluminum

In order to solve the problem of poor performance of welded joints of steel and aluminum dissimilar materials, this study proposes the use of ceramic particle-reinforced aluminum alloy as an alternative to traditional aluminum alloy for welding, effectively overcoming this problem. In this paper, the laser welding of stainless steel/6061 aluminum alloy (SA) and stainless steel/TiC–TiB2 duplex nanoparticle-reinforced 6061 aluminum alloy (SRA) was realized. The effect of ceramic nanoparticles on the microstructure and mechanical properties of SRA joint was systematically studied, and the strengthening mechanism of nanoparticles was revealed. Under the same process parameters, the melting zone of SRA joint is larger and the intermetallic compound (IMCs) layer is narrower. Moreover, the grain size of the brittle Fe–Al compound phase in the IMCs layer is significantly reduced, which effectively inhibits the initiation of cracks at the steel/aluminum interface. The study shows that ceramic particles have a pinning effect on the dislocations, limiting the grain growth, reducing the thickness of the intermetallic compound layer, and decreasing the content of the brittle FeAl3 phase. Moreover, ceramic nanoparticles promote the formation of Mg2Si strengthened phase at the grain boundary, further hinder the dislocation movement and improve the strength of the joint. Under the welding power of 3400 W and welding speed of 31 mm/s, SRA joint achieves the maximum tensile shear of 1718 N, which is 15% higher than the strength of SA joint.

Study on the microstructure and mechanical properties of hot rolled nano-ZrB2/AA6016 aluminum matrix composites by friction stir processing

In this paper, in-situ ZrB2/AA6016 particle-reinforced aluminum matrix composites were prepared in molten A6016 aluminum alloy melt by KBF4-Al- K2ZrF6 reaction system. For the first time, this paper presents that after casting, the composites would be subjected to large strain hot rolling (LSHR) with 60 % undercutting and then friction stir processing (FSP) with a stirred probe speed of 1200 r/min and a traveling speed of 60 mm/min. To study the microstructure and mechanical properties of composites strengthened by large strain hot rolling combined with friction stir processing. The results show that the tensile strength of the base material is 140.1 MPa, the elongation is 46.3 %, the product of strength and elongation reaches 6.5 GPa%, and the average hardness is 43.4 HV; The tensile strength of LSHR+FSP nugget zone is 163.4 MPa, the elongation is 78.9 %, the product of strength and elongation reaches 12.9 GPa %, which is about 98.6 % higher than the base material, and the average hardness is 59.8 HV, which is about 37 % higher than the base material. SEM, EBSD, and TEM analyses showed that the average grain size is refined from 189.7 μm to 3.8 μm after LSHR+FSP. The ZrB2 particles are sufficiently fragmented, with a particle size of about 20 nm, and uniformly dispersed in the matrix. This study provides the theoretical and experimental basis for applying nanoscale ZrB2 particles reinforcing ultrafine crystalline aluminum matrix composites prepared by LSHR + FSP.

Numerical simulation study on hot pressing of ceramic/metal powders

This study utilizes the multi-particle finite element method (MPFEM) to establish 2D and 3D hot pressing models for particle-reinforced aluminum matrix composites. The hot pressing of 6061Al powder and 10 % volume fraction SiCp/6061Al composite powder are simulated under a temperature range of 430–510 °C and pressures ranging from 15 to 30 MPa. The densification mechanism of the composites is elucidated by analyzing the evolution of density and microscopic particle behavior. The analysis reveals that elevating both the pressing temperature and pressure effectively increases the relative density of the powders, with the maximum growth rate occurring at 25 MPa. Notably, the barrier effect created by SiC particles in the 6061Al matrix restricts the plastic deformation and flow of matrix particles, leading to a lower final relative density for the composite powder compared to pure 6061Al powder. Microscopic observations indicate that particle rearrangement dominates in the initial pressing stage, while plastic deformation and particle flow become crucial factors for enhancing relative density in the later stage. Further stress-strain analysis demonstrates that 6061Al particles effectively fill pores through plastic deformation, resulting in stress concentration primarily on the harder SiC particles.

Experimental Studies of the Machinability of SiCp/Al with Different Volume Fractions under Ultrasonic-Assisted Grinding.

High-volume fraction silicon carbide particle-reinforced aluminum (SiCp/Al) has a promising application for its high specific strength, wear resistance, and thermal conductivity. However, SiCp/Al components with a high-volume fraction are prone to poor surface quality and defects such as fractures, cracks, and micro-pits. It has been reported that ultrasonic-assisted grinding machining (UAG) helps to improve the quality of SiCp/Al machined surfaces. However, the differences between SiCp/Al with different volume fractions obtained by UAG machining are not clear. Therefore, a comparative study of surface roughness, morphology, and cutting force was carried out by UAG machining on SiCp/Al samples with volume fractions of 45% and 60%. Compared to the 45% volume fraction SiCp/Al, the 60% volume fraction SiCp/Al has a higher cutting force and roughness under the same machining parameters. In addition, experiments have shown that cutting forces and surface roughness can be reduced by increasing the tool speed or decreasing the feed rate. UAG machining with an ultrasonic amplitude within 4 μm can also reduce cutting forces and surface roughness. However, more than 6 μm ultrasonic amplitude may lead to an increase in roughness. This study contributes to reasonable parameter settings in ultrasonically-assisted grinding of SiCp/Al with different volume fractions.

Deformation and fracture of SiCp/Al composites under complex loading conditions: A simulation study

An accurate depiction of the deformation and fracture mechanisms of metal matrix composites is the key to their rational structure and property design. In the present work, the Advanced Guerson Tvergaard Needleman (AGTN) constitutive model is firstly combined with an algorithm to reconstruct realistic 3D microstructures within the finite-element framework. We employ this model to probe the elastoplastic response and fracture behaviors of aluminum matrix composites with different volume fractions of reinforcing particles (7, 14, and 21 %) and under various loading conditions (tension, compression and shear). Real microstructures are referred to reconstruct the three-dimensional model of the composites. The AGTN constitutive model is integrated with the micromechanical damage model, which is capable of independently describing the constitutive behavior of various components, including the elastoplastic damage of the metal matrix, particle-enhanced elastic-brittle failure, and the interfacial traction separation. By using the conventional SiCp/Al composite system as a model material, we examine the stress state of the matrix and fracture mechanisms under different loading conditions by using triaxiality, Lode angle and statistical analysis. In general, the damage of SiCp/Al composites can be attributed to interfacial debonding and particle fracture, whereas the latter dominates when the volume fraction of SiCp is high. Furthermore, the critical volume fraction for the transition of damage mechanisms is found to be largely dependent on the loading conditions. Our work provides a comprehensive understanding of particle-reinforced aluminum matrix composite under in-service conditions.

Porosity suppression and mechanical property improvement of wire-arc directed energy deposited TiCp/Al-Cu alloys joint by oscillating pulsed wave laser beam welding

Hybrid manufacturing technology combining wire-arc directed energy deposition (WA-DED) and laser beam welding (LBW) presents a promising avenue for efficiently manufacturing large-size aluminum alloy components. The high tendency of porosity defects, particle decomposition, and fusion zone softening are outstanding challenges in the LBW welding of additively manufactured particle-reinforced aluminum alloys. Herein, a WA-DED-processed Al-6.3Cu alloy embedded with 0.6 wt% TiC particles was employed as weldment. Four different laser beam modes, including continuous wave (CW), pulsed wave (PW), oscillating continuous wave (OCW), and oscillating pulsed wave (OPW), were used to join TiCp/Al-6.3Cu alloy. The effects of different laser modes on the porosity defects, microstructure evolution, and mechanical properties of WA-DED particle-containing aluminum alloy joints were studied comparatively. Multi-scale characterization results showed that the enhanced molten pool flow via laser beam modulation effectively suppressed porosity defects and facilitated the uniform particle distribution. The OPW mode provides an optimal effect on porosity inhibition and weld microstructure refinement compared to the pulsed or oscillating modulation modes. The heat-treated LBW joint via OPW mode achieved excellent comprehensive mechanical properties, whose elongation and ultimate tensile strength reached 9.5% and 449 MPa, respectively. This enhanced performance can be attributed to the decreased porosity, refined weld microstructure, and high-density nano-precipitation. This study provides fundamental guidance for the welding of high-strength Al-Cu alloy fabricated by additive manufacturing.

Evolution of microstructure and mechanical properties of aluminum matrix composites reinforced with dual-phase heterostructures

The trade-off between strength and plasticity has long been challenging in particle-reinforced aluminum matrix composites (PRAMCs). This study proposes an innovative approach for preparing aluminum matrix composites (AMCs) using a dual-phase hybrid of FeCoNiCrMn high entropy alloy (HEA) and multiscale aluminum oxide (Al2O3) particles. The microstructure evolution and strengthening mechanisms were evaluated through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results demonstrated that the dual-phase particle strengthening resulted from the alternating distribution and synergistic action of HEA and Al2O3 particles within the matrix, forming a continuous strain buffer with a strength gradient. Notably, introducing HEA and nano-Al2O3 led to a higher density of dislocations. Additionally, EBSD analysis revealed a uniform strain distribution within the AMCs, with a significant concentration of kernel average misorientation (KAM) near the grain boundaries (GBs). In terms of micromechanical properties, the micro-zones of heterogeneous phases exhibit exceptionally high elastic modulus and nanohardness. In terms of macroscopic mechanical properties, the material exhibited impressive ultimate compressive strength and compression ratio values of 447.9 MPa and 37.9 %, respectively. These results represented a remarkable enhancement of 72.1 % and 6.6 % compared to the single FeCoNiCrMn HEA strengthening. Moreover, when applying the HEA + nano-Al2O3 blending mode, the ultimate compressive strength further increased to 506.7 MPa, representing an astonishing boost of 94.7 %. This significant strength improvement can be attributed to effective interfacial bonding, grain refinement, and a high dislocation density resulting from both HEA and Al2O3 particles.

Microstructure and properties of in situ Al2O3 particle-reinforced aluminium alloy lattice rods fabricated by wire-arc-directed energy deposition

Lattice structures have great potential for application in the thermal protection systems of high-performance hypersonic vehicles (Mach > 5). They are lightweight, highly load-bearing and provide good heat insulation. Wire-arc directed energy deposition (WA-DED) is an effective method for preparing lattice structures made from metal lattice rods. A method is proposed to improve the ultimate tensile and compressive strengths of aluminium (Al) alloy lattice rods and lattice structures made by WA-DED. The replacement reaction of Al and NiO generates Al2O3, which was used to improve an Al–Cu alloy (2xxx series). An Al–Cu–NiO system cored wire filled with NiO particles was developed as the raw material for studying WA-DED lattice rods. Then the rod was heat treatment. Tests show that the strength of in situ Al2O3-particle-reinforced Al alloy rods was 281 MPa, which is 13.9% higher than that of Al–Cu 2319 Al alloy deposited rods. Reinforcement also increased the elongation (EL) from 11.3% to 13.5%. Strength is increased by Al and NiO reacting in situ to form an Al2O3 phase with refined grains. Most of the generated Ni is dissolved in Al2Cu to form a nano γ-Al7Cu4Ni phase, which plays a second-phase strengthening role. After T6 heat treatment, the strength and EL of 2319-NiO-cored wire deposited rods was 441 MPa and 10.4%. Fine, needle-like θ’-Al2Cu structures and Al2O3 and γ-Al7Cu4Ni nanoparticles pin dislocations, prevent their movement and improve the mechanical properties of the rod. The compressive strength of a planar lattice structure after T6 heat treatment was 105 MPa and its weight was only 15 g, demonstrating high specific strength. Finally, arc additive manufacturing with the developed 2319-NiO-cored wire was used to fabricate a curved-generatrix-shell pyramid lattice structure for use in the thermal protection cone of a hypersonic vehicle. Its thermal insulation coefficient was 82.5%, demonstrating excellent insulation performance. This study provides insights into the manufacturing of thermal protection systems for lightweight, high-strength and high-heat hypersonic vehicles.

Research progress on aluminum matrix composites reinforced by medium and high volume fraction hybrid particles

Aluminum matrix composites reinforced with particles offer many advantages, including high specific strength, elevated specific stiffness, reduced thermal expansion coefficient, enhanced thermal conductivity, abrasion resistance, and dimensional stability. These composites find extensive application in aerospace, electronic packaging, and weaponry. The concept of hybrid particle reinforcement, involving multiple reinforcing particles, optimizes the performance attributes of each phase and the synergistic reinforcement effect, leading to potentially superior hybrid particle-reinforced aluminum matrix composites. This paper presents a comprehensive overview of the methods for preparing particle-reinforced aluminum matrix composites. It examines the toughening mechanisms in aluminum matrix composites reinforced with hybrid particles at medium and high volume fractions. These mechanisms include fine grain reinforcement, Orowan reinforcement, and heterogeneous deformation-induced reinforcement, including geometrically necessary dislocation reinforcement. This paper elucidates the role of micronano organizational structures-such as the morphology, size, distribution, and interfacial bonding state of hybrid particles and matrix-in determining the comprehensive performance of aluminum matrix composites. Additionally, it explores the effect of hybrid particle morphology, size, distribution, and micronano structure on the composite’s overall performance. Finally, future research directions and trends in the development of high-performance hybrid particle-reinforced aluminum matrix composites are discussed.

Microstructure and Properties of Aluminum-Graphene-SiC Matrix Composites after Friction Stir Processing.

Enhancing the mechanical properties of conventional ceramic particles-reinforced aluminum (Al 1060) metal matrix composites (AMCs) with lower detrimental phases is difficult. In this research work, AMCs are reinforced with graphene nanosheet (GNS) and hybrid reinforcement (GNS combined with 20% SiC, synthesized by shift-speed ball milling (SSBM), and further fabricated by two-pass friction stir processing (FSP). The effect of GNS content and the addition of SiC on the microstructure and mechanical properties of AMCs are studied. The microstructure, elemental, and phase composition of the developed composite are examined using SEM, EDS, and XRD techniques, respectively. Mechanical properties such as hardness, wear, and tensile strength are analyzed. The experimental results show that the GNS and the SiC are fairly distributed in the Al matrix via SSBM, which is beneficial for the mechanical properties of the composites. The maximum tensile strength of the composites is approximately 171.3 MPa in AMCs reinforced by hybrid reinforcements. The tensile strength of the GNS/Al composites increases when the GNS content increases from 0 to 1%, but then reduces with the further increase in GNS content. The hardness increases by 2.3%, 24.9%, 28.9%, and 41.8% when the Al 1060 is reinforced with 0.5, 1, 2% GNS, and a hybrid of SiC and GNS, respectively. The SiC provides further enhancement of the hardness of AMCs reinforced by GNS. The coefficient of friction decreases by about 7%, 13%, and 17% with the reinforcement of 0.5, 1, and 2% GNS, respectively. Hybrid reinforcement has the lowest friction coefficient (0.41). The decreasing friction coefficient contributes to the self-lubrication of GNSs, the reduction in the contact area with the substrate, and the load-bearing ability of ceramic particles. According to this study, the strengthening mechanisms of the composites may be due to thermal mismatch, grain refinement, and Orowan looping. In summary, such hybrid reinforcements effectively improve the mechanical and tribological properties of the composites.

Aluminum carbide formation in Al-graphite composites: In situ study and effects of processing variables and sintering method

The particulate-reinforced aluminum–matrix composites are interesting due to their attractive physical and mechanical properties over their monolithic counterparts, which are related to their prominent structural differences. The effect of interfacial reaction on the mechanical properties of the Al composites has been attributed to the influence of the reaction product. In this work, the formation of Al4C3 in Al-Gr compounds prepared by high-energy ball milling and sintered by high-frequency induction is compared with a conventional method of sintering: cold compaction and furnace sintering. The conditions related to the generation of this carbide and a precise temperature in which the initial generation of this phase occurs were determined. The different results and the in-situ characterization using HR-TEM showed the substantial reactivity of graphite in the aluminum matrix, leading to the formation of the Al4C3 phase within a few seconds of heating to 250 °C. The conventionally sintered samples displayed the highest number and size of Al4C3 precipitates. In contrast, the heated sample exhibited varied quantities and sizes of these precipitates. Notably, the high-frequency induction sintered samples contained smaller Al4C3 precipitates with a lower number density. Structural, microstructural, and chemical composition results of this phase formed in Al-Gr composites are also shown.

Pulsed Laser Ultrasonic Vibration-Assisted Cutting of SiCp/Al Composites through Finite Element Simulation and Experimental Research

Silicon carbide particle-reinforced aluminum matrix composites (SiCp/Al) find diverse applications in engineering. Nevertheless, SiCp/Al exhibit limited machinability due to their special structure. A pulsed laser ultrasonic vibration assisted cutting (PLUVAC) method was proposed to enhance the machining characteristics of SiCp/Al and decrease surface defects. The finite element model was constructed, considering both the thermal effect of the pulsed laser and the location distribution of SiC particles. The model has been developed to analyze the damage forms of SiC particles and the formation mechanisms for the surface morphology. The influence of pulsed laser power on average cutting forces has also been analyzed. Research results indicate that PLUVAC accelerates the transition from the brittleness to the plastic of SiC particles, which helps to reduce surface scratching caused by fragmented SiC particles. Furthermore, the enhancement of surface quality is attributed to the decrease in surface cracks and the beneficial coating effect of the Al matrix. The accuracy of the simulation is verified by experiments, and the feasibility of PLUVAC method to enhance the surface quality of SiCp/Al is confirmed.

Investigations on tensile mechanical properties of rigid insulation tile materials at elevated temperatures based on digital image correlation algorithm

This work investigates the tensile mechanical properties of rigid insulation tile (RIT) materials at room temperature (26 °C) and elevated temperatures (700–1000 °C) through experimental and digital image correlation (DIC) methods. Experimental results indicate that the tensile strength of RIT materials changes nonlinearly with increasing temperature and that the primary fracture mode under tension load is fiber root fracture. In terms of the DIC algorithm, this work builds an elevated-temperature DIC test system. A zero-mean Gaussian filtering algorithm and an image gradient difference square sum algorithm (SSDGI) are proposed to improve the precision of the DIC algorithm. The derived tensile stress-strain curve of RIT materials reveals that the elastic modulus changes nonlinearly with increasing temperature. The reliability and precision of the DIC algorithm are confirmed through the tensile test of silicon carbide particle-reinforced aluminum matrix composites. Hence, this work provides guidance for evaluating mechanical properties of RIT materials under elevated temperature environments.

Hot Deformation Behavior and Mechanisms of SiC Particle Reinforced Al-Zn-Mg-Cu Alloy Matrix Composites

A systematic and comprehensive analysis of the hot deformation and mechanisms of SiC particle-reinforced aluminum matrix composites is significant for optimizing the processing of the composites and obtaining the desired components. Based on this, related research on 11 vol% SiCp particle-reinforced 7050Al matrix composites was carried out. Hot compression experiments were carried out on the Gleeble-3500 thermal simulator to study the hot deformation behavior of composites at the temperature of 370–520 °C and strain rate of 0.001–10 s−1. The hyperbolic sine constitutive equation of the material was established, and the processing map was calculated. Combining the typical metallograph and misorientation angle distribution, the microstructure evolution mechanism of composites was analyzed, and the effect of particles on recrystallization behavior was investigated. Under certain process conditions, the dominant deformation mechanism of composites changed from dynamic recovery (DRV) to dynamic recrystallization (DRX), and the grain boundary sliding mechanism began to play a role. In addition, high temperature tensile and elongation at break were tested, and it was found that the dominant form of fracture failure changed from brittle fracture of the particles to ductile fracture of the matrix as the temperature increased.

Effects of solution temperatures on microstructures and mechanical properties of B4C/7A04Al composites: A comparison study with 7A04Al alloys

To prepare particle-reinforced aluminum matrix composites with ultra-high strength, high-strength 7xxx Al alloys are commonly employed as matrices. Heat treatment plays a crucial role in enhancing the mechanical properties of the alloys and their composites, but the influence of solution temperatures on composites based on 7xxxAl alloys remains unexplored. In this study, the effects of solution temperatures on the microstructures and mechanical properties of B4C/7A04Al composites fabricated via powder metallurgy (PM) technology were investigated, as well as those of 7A04Al alloys for comparison. Before solution treatments, the prominent second phases in the composite were MgZn2 phases, while those in the 7A04Al alloy consisted of MgZn2 and Al2CuMg phases. At lower solution temperature (420 °C), MgZn2 phases dissolved completely, whereas Al2CuMg phases persisted. Al2CuMg phases dissolved at 450 °C, and thus the 7A04Al alloy obtained the optimum strength and elongation. Further elevating the solution temperature caused abnormal grain growth (AGG) in the 7A04Al alloy, leading to a deterioration of strength and plasticity. In contrast, at various solution temperatures, the composite exhibited stability in grain size, which could be attributed to the pinning effects of B4C particles and Mg(Al)B2 phases, the reaction products between the boron impurity and the Al matrix. However, at higher solution temperatures (510 °C and 600 °C), the segregation of Mg and O around B4C particles was aggravated, and thus the elongation of the composite deteriorated. Interestingly, the strength remained relatively unaffected due to the strengthening effects of Mg(Al)B2 phases. The results indicate that the composite exhibited a broad range of solution temperature with comparable strength and elongation across a temperature range of 420 °C–470 °C. But for the 7A04Al alloy, the optimal solution temperature is 450 °C.