Search Results (160)

Copper (Cu) is widely used in electrical, electronic, and tribological systems owing to its excellent electrical and thermal conductivity. However, its relatively low hardness and poor wear resistance limit its use in demanding engineering applications. In this study, Cu-based hybrid metal matrix composites (MMCs) reinforced with hexagonal boron nitride (h-BN) and boron carbide (B₄C) were fabricated via spark plasma sintering (SPS) to improve their mechanical and tribological performance. The h-BN content was fixed at 1 wt.% to ensure solid lubrication, while the B₄C content was varied (0.25, 0.5, 0.75, and 1 wt.%) to examine its influence on the microstructural, mechanical, electrical, and wear properties of the composites. Microstructural analyses confirmed a homogeneous distribution of h-BN and B₄C particles in the Cu matrix at low and moderate reinforcement levels, whereas excessive B₄C resulted in partial agglomeration and reduced densification. All composites achieved relative densities above 95%, demonstrating the high densification efficiency of the SPS process. Hardness increased markedly with B₄C addition due to dispersion strengthening and grain refinement, while electrical conductivity decreased slightly because of the insulating nature of the reinforcements. Tribological tests showed that the composite containing 0.75 wt.% B₄C exhibited the best performance, with the lowest wear rate and stable friction behavior. Overall, the results indicate that co-reinforcing Cu with h-BN and B₄C through SPS is a promising strategy for developing multifunctional materials suitable for electrical contact and sliding applications. Full article

Lightweight metal matrix composites (MMCs) continue to attract significant interest due to their potential to deliver high mechanical performance at reduced weight, meeting the increasing demands of aerospace, automotive and advanced manufacturing sectors. Among these systems, aluminum-, magnesium- and titanium-based MMCs stand out for their favorable strength-to-weight ratios, corrosion resistance and versatility in processing. Although numerous studies have explored individual MMC families, the literature still lacks comparative reviews that integrate quantitative mechanical data with a broad evaluation of processing, microstructural control and application-driven performance. This review addresses these gaps by providing a comprehensive and data-driven assessment of lightweight MMCs. Recent advances in reinforcement strategies, hybrid architectures and processing routes—including friction stir processing, powder metallurgy and semi-solid techniques—are systematically examined. Emerging developments in syntactic metal foams and functionally gradient MMCs are analyzed in detail, along with practical considerations such as machinability, corrosion resistance, and high-temperature performance, integrated with AI/machine learning for predictive optimization. Overall, this work provides an integrated and critical perspective on the capabilities, limitations, and design trade-offs of lightweight MMCs, positioning them as sustainable and high-performance alternatives for extreme environments. By combining qualitative insights with quantitative meta-analyses and new experimental contributions, it offers a valuable reference for researchers and engineers seeking to optimize material selection and tailor the performance of MMCs for next-generation lightweight structures, surpassing previous reviews through holistic and innovation-driven insights. Full article

Al–Cu–Mg composites reinforced with sub-micron tungsten carbide (WC) particles were synthesized by powder metallurgy and subjected to T6 heat treatment to clarify the interplay between dispersion strengthening and precipitation hardening. Composites with 1–3 wt.% WC (average size 0.8 μm) were solution-treated at 540 °C for 3 h, water-quenched, and aged at 195 °C for up to 100 h. Microstructural analyses confirmed a uniform distribution of WC and demonstrated that its presence did not modify the dissolution–precipitation sequence of the Al-Cu-Mg matrix. Transmission Electron Microscopy observations provided direct evidence of θ′ (Al₂Cu) precipitates. The 3 wt.% WC composite reached peak hardness after 5 h (78 HRF), a 15% increase over the T6-treated unreinforced alloy, and exhibited a 40% higher yield strength (330 MPa). These improvements were attributed to the combined effects of Orowan strengthening and age-hardening precipitates (θ′). The results demonstrate that integrating powder metallurgy, sub-micron WC reinforcement, and T6 treatment is an effective route to enhance strength in Al–Cu–Mg alloys without delaying aging kinetics. Full article

Al-W composites are lightweight, high-strength, structural–functional integrated materials with tailorable density and excellent X/γ-ray shielding performance, making them promising candidates for nuclear and aerospace applications. In this study, high-W-content 2024Al-W composites were successfully fabricated via spark plasma sintering (SPS) at a relatively low temperature of 440–500 °C. With increasing sintering temperature, the relative density of the composites increased from 99.6% to 99.9%. A ternary intermetallic compound, Al₁₈Mg₃W₂, was first detected at the Al/W interface at 460 °C. At 480 °C, submicrometre Al₁₈Mg₃W₂ phases formed and cooperated with nanoscale Al₂Cu precipitates, effectively enhancing interfacial bonding and optimizing mechanical properties—yielding an ultimate tensile strength of 266.9 MPa and an elongation of 6.2%. Among the strengthening mechanisms, coefficient of thermal expansion (CTE) mismatch strengthening contributed the most (~19.2 MPa), followed by load transfer (~4.27 MPa) and Orowan strengthening (~1.17 MPa). These findings provide valuable insights into the low-temperature preparation of high-W-content Al-W structural–functional materials via SPS. Full article

Gradient structure provides an effective approach to improve the combination of high strength and toughness compared to a uniform one. The gradient interfaces or boundaries in gradient-structured metallic glass composites play a crucial role in influencing mechanical properties. Our findings indicate the gradient microstructure significantly induces temporal and spatial stress localization, which can modulate the generation and propagation of shear bands. The synergistic gradient effects generated by heterogeneous grain sizes and interface characteristics can enhance both the strength (yield stress and peak stress) and the toughness of gradient network-structured metallic glass composites as the grain size gradient and the boundary width increase. Our work demonstrates the appropriate gradient of grain size, and the boundary structure should potentially lead to enhanced work hardening. Full article

The corrosion behavior of open-cell AlSn6Cu-based composites, one reinforced with SiC particles and the other with Al₂O₃ particles, was investigated. The composites were fabricated via liquid-state processing, employing both squeeze casting and the replication method, and they produced in two distinct pore size ranges (800–1000 µm and 1000–1200 µm). Corrosion performance was systematically evaluated through gravimetric (weight loss) measurements and electrochemical techniques, including open-circuit potential monitoring and potentiodynamic polarization tests. Comprehensive microstructural and phase analyses were conducted using X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The results revealed that both reinforcement type and pore architecture have a significant impact on corrosion resistance. Al₂O₃-reinforced composites consistently outperformed their SiC-containing counterparts, and pore enlargement generally improved performance for the unreinforced alloy and the Al₂O₃ composite but not for the SiC composite. Overall, the optimal corrosion resistance is achieved by pairing a coarser-pore architecture (1000–1200 µm) with Al₂O₃ reinforcement, which minimizes both instantaneous (electrochemical) and cumulative (gravimetric) corrosion metrics. This study addresses a gap in current research by providing the first detailed assessment of corrosion in open-cell AlSn6Cu-based composites with controlled pore architectures and different ceramic reinforcements, offering valuable insights for the development of advanced lightweight materials for harsh environments. Full article

This study systematically investigates the synergistic corrosion resistance enhancement mechanisms in aluminum matrix composites (AMCs) through the combined implementation of equal channel angular pressing (ECAP) and Ti₃C₂T_x MXene reinforcement. The results demonstrate that ECAP treatment significantly refines the microstructure, reducing grain sizes to an average of 8.7 µm after three passes, while improving mechanical properties such as hardness by 40.6–45.1%. Additionally, the incorporation of Ti₃C₂T_x enhances corrosion resistance by establishing a physical barrier that impedes the diffusion of corrosive mediators and prevents localized corrosion. Electrochemical tests reveal that the composite subjected to three ECAP passes exhibits the lowest corrosion current density (I_corr) and a remarkable 3.4-fold increase in charge transfer resistance (R_ct) compared to untreated material. These findings highlight the potential of synergistically integrating ECAP and Ti₃C₂T_x to develop high-performance AMCs with enhanced mechanical strength and corrosion resistance, offering significant implications for applications in marine equipment, aerospace, and new energy vehicles. Full article

Nickel matrix composites reinforced with T15 high-speed steel (HSS) were prepared using powder metallurgy techniques. A systematic investigation was conducted into the effect of CeO₂, MoS₂, and graphite additives on the tribological properties of the composites. The results show that when T15 HSS particles are added, nickel grains do not grow as much as they do in pure sintered nickel. It was also observed that the T15 HSS particles were diffusion-bonded to the nickel matrix after sintering. The highest relative density after sintering is obtained for composites containing graphite, but the maximum hardness of 243 HV can be achieved for composites containing 2% of CeO₂, which is about 16% higher than that of the Ni-T15 HSS composite. The wear rate of Ni-T15 HSS composites reduces from 3.4782 × 10⁻⁷ cm³/N∙m to 2.0222 × 10⁻⁷ cm³/N∙m as the content of CeO₂ rises from 0 wt.% to 2 wt.%. The wear mechanisms of composites with MoS₂ or graphite are abrasive wear and adhesive wear. The introduction of CeO₂ enhances the hardness of the investigated composites to the highest degree, leading to a change in the wear mechanism of the composites to slight abrasive wear. The addition of CeO₂ can effectively optimize the tribological properties of Ni-T15 HSS composites. Full article

The structural, mechanical, dislocation, and electronic properties of the Sc₃AlC MAX phase under applied pressure are investigated in detail using first-principles calculations. Key parameters, including lattice parameter ratios, elastic constants, Young’s modulus, bulk modulus, shear modulus, brittle-to-ductile behavior, Poisson’s ratio, anisotropy, Cauchy pressure, yield strength, Vickers hardness, and energy factors, are systematically analyzed as a function of applied pressure. The results demonstrate that the Sc₃AlC MAX phase exhibits remarkable mechanical stability within the pressure range of 0 to 60 GPa. Notably, applied pressure markedly improves its mechanical properties, such as resistance to elastic, bulk, and shear deformations. The B/G ratio suggests a tendency toward ductile behavior with increasing pressure, and the negative Cauchy pressure indicates the directional characteristics of interatomic bonding in nature. Vickers hardness and yield strength increase under pressures of 0 to 10 GPa and then decrease sharply above 50 GPa. High pressure suppresses dislocation nucleation due to the increased energy factors, along with twinning deformation. Furthermore, electronic structure analysis confirms that high pressure enhances the interatomic bonding in the Sc₃AlC MAX phase, while the enhancement effect is not substantial. This study offers critical insights for designing MAX phase materials for extreme environments, advancing applications in aerospace and electronics fields. Full article

In this paper, the synthesis of TiC-coated carbon fibers (TiC-CFs) with varying thicknesses is achieved through the manipulation of the molten salt reaction, along with the fabrication of TiC-coated carbon fiber-reinforced aluminum matrix (TiC-CF/Al) composites via the vacuum pressure infiltration technique. The results show that modulating the holding time of the molten salt reaction significantly enhances the wettability between the carbon fiber (CF) and the aluminum, thereby augmenting the mechanical integrity of the composite materials. Should the holding time be excessively short, the coating on the CF surface develops an uneven distribution, and its efficacy in obstructing the direct interaction with the aluminum is inadequate. As the holding time prolongs, the TiC coating thickens, achieving a comprehensive coverage after 2 h of holding. The presence of a pristine TiC coating on the CF surface not only optimizes the wettability with the aluminum melt but also mitigates the reaction between the CF and aluminum. However, an excessively thick coating not only reduces the strength of the fibers, due to excessive reactions, but also makes the coating prone to detachment during the preparation process due to stress. At a holding time of 3 h, the tensile strength of the CF/Al composite material reaches its highest value, with a tensile strength of 103.93 MPa and an impressive 72.35% enhancement over that of the aluminum. Full article

Cu-based alloys and composites are popular to prepare electroconductive parts. However, their processing can be challenging, especially in case of composites strengthened with oxides. To save the necessary time and costs, numerical simulations can be of help when determining the deformation behaviour of (newly introduced) materials. The study presents a combined method of strengthening of Cu by adding 5 wt.% of La₂O₃ particles and performing shear-based deformation by equal channel angular pressing (ECAP). The effects of the method on the microstructure, mechanical properties, and thermal stability of the composite are examined both numerically and experimentally. The results showed that the La₂O₃ addition caused the maximum imposed strain to be higher for the composite than for commercially pure Cu, which led to the development of subgrains and shear bands within the microstructure, and a consequent increase in microhardness. The numerical predictions revealed that the observed differences could be explained by the differences in the material plastic flow (comparing the composite to commercially pure Cu). The work hardening supported by the addition of La₂O₃ led to a significant increase in stress and punch load during processing, as well as contributed to a slight increase in deformation temperature in the main deformation zone of the ECAP die. Certain inhomogeneity of the parameters of interest across the processed workpiece was observed. Nevertheless, such inhomogeneity is typical for the ECAP process and steps prospectively leading to its elimination are proposed. Full article

The effects of extrusion temperatures on the microstructure, mechanical properties, and corrosion performance of biomedical Mg-1Zn-0.4Ca-1MgO composites were systematically investigated. The results indicated that lower extrusion temperatures notably refined the grain size and promoted the formation of numerous nano-scaled secondary phase particles. The grain sizes were 0.8 μm, 1.7 μm, and 3.4 μm for the materials extruded at 280 °C, 310 °C, and 330 °C, which were named ET280, ET310, and ET330. The finest grain size and abundant precipitates enhanced the mechanical properties of the composite with a microhardness of 86.9 HV, a yield strength of 305 MPa, and a fracture elongation of 15.2%. Moreover, the ET280 alloy with ultra-fine grains exhibited the optimal corrosion resistance among these three composites, and its annual corrosion after immersion in Hank’s solution for 14 days was only 0.17 mm/y. The excellent performance in vitro immersion was mainly attributed to the formation of the uniformly dense Ca-P layer on its surface and the contiguous compact Mg(OH)₂ layer, which could effectively weaken the contact between the corrosive solution and the Mg matrix. Full article

Cemented carbide (WC-Co) combines high hardness, wear resistance, and toughness, making it ideal for tooling applications. This study investigated cryogenic treatment’s effects on the mechanical properties of samples from various suppliers prepared at different scales. Indentation tests were performed to assess the mechanical properties at the microscale and nanoscale. Overall, the mean microhardness did not show a significant change after cryogenic treatment. Instead, nanoindentation testing was used to identify the improvement after cryogenic treatment. However, considering the mean nanohardness may not adequately capture improvements in the material’s resistance to deformation, the maximum nanoindentation depth and nanohardness were analyzed to elucidate the mechanisms underlying mechanical property improvements in the form of histograms of %frequency along with load–displacement curves. The results showed a decreased frequency of high maximum indentation depths from Co phase improvement. This agreed with an increased frequency of moderate and high nanohardness and a decreased frequency of low nanohardness representing different areas with different phase controls. These results indicate that an alternative interpretation of nanoindentation data, presenting nanohardness and nanoindentation depth in the form of histograms, can provide a more detailed representation of the data distribution. Full article