SiCp/Al composites are promising for train brake discs, yet the mechanisms of particle size-governed frictionthermal behavior remain unclear. This study evaluated the friction and thermal performance of SiCp/Al composites with varying SiC sizes (10, 20, and 40 mu m) through simulated braking and mesoscale discrete element method (DEM) simulations. Results indicated that coarse SiC (40 mu m) enhanced thermal conductivity by forming a continuous conduction network and provided superior mechanical locking, suppressing damage propagation to achieve optimal heat dissipation and wear resistance. However, under the investigated conditions, moderate SiC (20 mu m) promoted a stable third-body layer, facilitating a rapid transition to a stable friction regime and dynamic wear balance. This research clarified how particle size regulates the interfacial friction-thermal evolution, providing critical theoretical and experimental guidance for optimizing reinforcement architecture in SiCp/Al brake discs under practical service conditions.

A thermo-mechanical-wear finite-element model coupled with cohesive-zone method is proposed to simulate potential failure pattern of an aluminum-based composite brake disc under frictional thermal loads. The analysis reveals that during cooling, a pronounced axial stress mismatch develops at the composite/substrate interface near the inner ring, driving interfacial delamination. Damage initiates at localized high-stress sites and propagates circumferentially until arrest. Composite layer thickness is critical: an optimal AMMC layer thickness reduces thermal gradients and peak stresses, mitigating delamination, whereas excessive thickness is counterproductive. These findings highlight the role of interface stresses and layer design in preventing composite-layer failure under braking.

Aluminum matrix materials are essential for lightweight structural applications, yet their performance under high-temperature cyclic loading is constrained by microstructural instability. This study presents a novel synthesis route initiated at the powder precursor stage to fabricate an in-situ (Al2 O3 + Al3 Ti)/Al composite. The approach combines a hybrid sol-gel process with powder metallurgy, first establishing a reinforcement network along grain boundaries and then enabling partial incorporation of the reinforcements into grain interiors, thereby achieving synergistic strengthening through coordinated intra- and intergranular mechanisms. The composite exhibits exceptionally high-cycle fatigue resistance at 350 degrees C, delivering a fatigue strength of 97 MPa-significantly higher than that of conventional heat-resistant aluminum alloys. Through multi-scale characterization using X-ray computed tomography, neutron diffraction, and microstructural analysis, the underlying strengthening mechanisms were systematically elucidated. Nanosized Al2 O3 particles effectively pin dislocations and suppress grain coarsening, promoting stable dislocation networks that enhance microstructural stability, while the Al3 Ti intermetallic phase contributes to load-bearing capacity and alleviates stress concentration through anti-phase boundary formation. The synergistic combination underpins the composite's excellent fatigue endurance, offering valuable insights for designing advanced aluminum matrix composites with enhanced thermal stability. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Carbon nanotube (CNT) reinforced aluminum matrix composites (CNT/Al) featuring distinct matrix alloys were crafted utilizing a synergistic approach that integrated high energy ball milling with powder metallurgy techniques. The influence of matrix alloy composition on the tribological behavior of CNT/Al composites was investigated. CNT/2009Al composite demonstrates lower friction coefficients and wear rates than CNT/6061Al, while also significantly reducing the wear rate of its counterpart under varying loads by generating an extensive mechanical mixture layer (MML) on its worn surface, while simultaneously hindering the formation of MML on the worn counterface. But for CNT/6061Al, the spalling of substantial material fragments during wear processes led to pronounced delamination wear, particularly under high load. This underscores the superior suitability of high-strength and tough aluminum alloys as matrices for composites, particularly tailored for applications that necessitate components exhibiting wear resistance.

The effectiveness of the room-temperature strengthening strategy for aluminum (Al) is compromised at increased temperatures due to grain and precipitate phase coarsening. Overcoming the heightened activity of grain boundaries and dislocations poses a significant challenge in enhancing the high-temperature strength through traditional precipitation strengthening. This study presents novel strengthening strategies that integrate intergranular reinforcements, intragranular reinforcements, refined grain, and stacking faults within an (Al2O3+Al3Ti)/Al composite prepared using sol-gel and powder metallurgy technology. Excellent high-temperature tensile properties are achieved; also, a remarkable fatigue performance at increased temperatures that surpasses those of other existing Al alloys and composites is revealed. These superior characteristics can be attributed to its exceptionally stable microstructure and the synergistic strengthening mechanisms mentioned above. This work offers new insights into designing and fabricating thermally stable Al matrix composites for high-temperature applications.

用真空热压法制备不同B4C颗粒尺寸(7 μm、14 μm、20μm)的15％B4C/Al-6.5Zn-2.8Mg-1.7Cu复合材料,研究了增强颗粒尺寸对其微观组织和力学性能的影响.结果表明,在这三种复合材料中B4C颗粒均匀分布,B4C-Al界面反应较为轻微,未见明显的界面反应产物.三种复合材料基体中沉淀相的尺寸基本相同(约为5.5 nm).B4C颗粒的尺寸对复合材料力学性能有较大的影响.B4C颗粒尺寸为7 μm的复合材料性能最佳,屈服强度为648 MPa,抗拉强度为713 MPa,延伸率为3.3％.随着颗粒尺寸的增大复合材料的强度和延伸率均降低.对三种复合材料的强化机制和断裂机制的分析结果表明:小尺寸B4C颗粒增强的复合材料强度较高,颗粒在变形过程中不易断裂,因此其塑性较好.

利用Al-La2O3的原位反应和粉末冶金工艺制备出(Al11La3+Al2O3)/Al复合材料.结果表明,高能球磨和高温烧结促进了原位反应,使Al与La2O3充分反应并制备出致密无缺陷的材料.对其微观组织的分析表明,微米Al11La3和纳米Al2O3颗粒均匀分散于基体之中.这种复合材料的室温抗拉强度为328 MPa、延伸率为10.5％,350℃的高温抗拉强度为119 MPa、延伸率为10.2％.与传统Al-Cu-Mg-Ag和Al-Si-Cu-Mg耐热铝合金相比,本文的制备的(Al11La3+Al2O3)/Al复合材料其高温抗拉强度提高了大约20％.这种材料的室温强化机制源于Al11La3和Al2O3的位错强化和载荷传递强化,而高温强化机制则源于A12O3的晶界钉扎.

As a classic in-situ reaction, the Al-TiO 2 reaction is expected to prepare aluminum matrix composites with high thermal stability. In this study, it was found that the preparation method of ensuring sufficient reaction using higher temperatures in previous studies was not conducive to acquiring optimized high-temperature strength. With the increase of hot-pressing temperature and the extension of holding time, the in-situ reaction became more thorough, but the strength of the composites first increased and then decreased. Coarsening of the microstructure at high temperatures would lead to degradation of strength and controlling the in-situ reaction process by the hot-pressing parameters could optimize the mechanical properties of the composites. Strengthening mechanisms at room and high temperatures were studied, and it was found that the load-transfer and Orowan strengthening mechanisms are the main strengthening effects at room temperature, while the pinning effect of fine particles became more crucial at elevated temperatures. As a result, the coarsening of the reinforcing phases was more detrimental to the high-temperature strength. Therefore, an insufficient in-situ reaction led to more excellent mechanical properties, and the composite hot-pressed at 605°C and held for 2 h exhibited the highest strength, which was 367 MPa at room temperature and 170 MPa at 350°C.

>Neutron absorbing materials （NAMs） are necessary in the nuclear industry for the storage and transportation of spent fuel.Among all the NAMs,B 4 C/Al composites are widely used because of the specific neutron absorption capacity[1–4].Compared with traditional low-strength functional NAMs such as B 4 C/1100Al and B 4 C/6061Al,NAMs with enough high-temperature （350℃） strength are competent for further structural usage and exhibit huge advantages in the dry storage of spent fuel because of heat transfer ability and weight reduction[5].

铝合金及其复合材料(铝基材料)具有低密度、高导热性、高比强度和高比刚度等一系列优点,被广泛应用在航空航天、交通运输以及军工等领域.目前,铝合金及其复合材料在室温力学性能方面和微观结构设计方面的研究已经取得了一定的进展,高温力学性能方面却表现得差强人意.近年来,随着航空航天、军工以及交通运输等领域的快速发展,高强耐热铝合金及其复合材料在实际应用中的需求快速增长.本文综述了耐热铝基材料的制备方法以及应用现状,阐述了现有制备方法的特点与不足之处,指出限制材料实际应用的几点关键因素,包括制备成本问题、工艺方法问题,并分析了耐热铝基材料的强化机制.最后提出设计耐热铝基材料的重点因素,并展望了耐热铝基材料的发展趋势.

Amorphous Al 2 O 3 -reinforced Al composite (am-Al 2 O 3 /Al) compacted from ultrafine Al powders for high-temperature usages confronts with drawbacks because crystallization of am-Al 2 O 3 at high temperatures will result in serious strength loss. Aiming at this unsolved problem, in this study, high-temperature Al materials with enhanced thermal stability were developed through introducing more thermally stable nano-sized particles via high-temperature pre-treatment of ultrafine Al powders. It was found that the pre-treatment at ≤ 550 °C could introduce a few Al 2 O 3 in the Al matrix and increase the strength of the composites, but the strength was still below that of am-Al 2 O 3 /Al because without being pinned firmly, grain boundaries (GBs) were softened at high temperature and intergranular fracture happened. When the pre-treatment was carried out at 600 °C, nitridation and oxidation processes happened simultaneously, producing large numbers of intergranular (AlN + γ -Al 2 O 3 ) particles. GB sliding and intergranular fracture were suppressed; therefore, higher strength than that of am-Al 2 O 3 /Al was realized. Furthermore, the (AlN + γ -Al 2 O 3 )/Al exhibited more superior thermal stability compared to am-Al 2 O 3 /Al for annealing treatment at 580 °C for 8 h. Therefore, an effective way to fabricate high-temperature Al composite with enhanced thermal stability was developed in this study.

(B4C+Al2O3)/Al composite designed for the dry storage of spent nuclear fuels was fabricated and then subjected to friction stir welding, at a welding speed of 100 mm/min and rotation rates of 400–800 r/min. Sound joints were obtained under all welding parameters; however, significant softening occurred in the nugget zone (NZ) for all the joints. Therefore, all the joints exhibited significantly decreased strength at both room temperature and high temperature compared with the base metal, with the joints fracturing in the NZs. Rotation rate exhibited no obvious effect on the tensile strength of the joints, but led to increased elongation as the result of the broadened NZs. The detailed microstructural examinations indicated that the welding thermo-mechanical effect broke up the near 3D amorphous Al2O3 netlike structure distributed at the Al grain boundaries, caused the coarsening of Al grains, and the agglomeration and crystallization of amorphous Al2O3, thereby resulting in the softening of the NZs and the reduction in the joint strength. Consequently, inhibiting the breakup and crystallization of 3D amorphous Al2O3 netlike structure is the key factor to improve the joint strength of the (B4C+Al2O3)/Al composite.

Particulate reinforced aluminum matrix composites have been widely used in industrial fields. In general, high strength aluminium alloys, such as 2024Al are employed to produce stronger composites. However, the composites with high strength Al-Zn-Mg-Cu alloys as the matrices are paid relative attentions. Therefore, the corresponding optimization for fabrication parameters has not been well understood. In the present work, SiC particles with volume fraction of 15% reinforced Al-7.5Zn-2.8Mg-1.7Cu (mass fraction, %) composites were fabricated using powder metallurgy (PM) technique at hot pressing temperatures of 500, 520, 540 and 560 degrees C. TEM, EPMA and tensile test were used to study the effect of hot pressing temperature on the microstructure and tensile properties of SiC/Al-Zn-Mg-Cu composites. The measured densities indicated that all the composites were completely condensed, no pores were observed. Undissolved phase containing Mg and Cu segregated in matrix of the composites hot pressed at 500 and 520 degrees C, resulting in instable tensile properties. With increasing hot pressing temperature to 540 degrees C Mg and Cu were uniformly distributed in the composites which exhibited the stable tensile proper- ties. With further increasing temperature to 560 degrees C, Mg segregated around SiC particles due to interface reaction. In this case, the content of MgZn2 phase was decreased, resulting in the reduction of tensile strength. HAADF-STEM and EDS analyses showed that the interface compounds were oxide of Mg and coarse MgZn2 phase.

Cold gas dynamic spray (cold spraying, CS) has emerged as a promising solid state manufacturing technique to fabricate thick metallic deposits with limited risk of oxidation, phase transformations and residual thermal stresses. As-sprayed deposits usually exhibit poor mechanical properties and often require post-spray heat treatments to reduce inter-splat defects. In most of the cases, traditional heat treatments offer limited benefits to rejuvenate the mechanical properties of the deposit. This preliminary work presents an effective way to modify the microstructure and improve the mechanical properties of cold sprayed A380 aluminum alloy. As-sprayed alloy deposits were subjected to hot rolling treatments with different thickness reductions. Results suggest that the hot rolled samples show better strength and ductility compared with their as-sprayed state. Microstructural evolution and resulting mechanical properties, at different processing conditions, were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), high resolution transmission electron microscopy (HRTEM) and tensile tests. Sample with thickness reduction of 40% displayed highest values of ultimate strength (UTS, 420 +/- 2.1 MPa) and elongation (Elf, 5 +/- 2.3%) compared with the corresponding values of as-sprayed (100 +/- 13.4 MPa, 0%) and conventionally heat treated (186 +/- 17 MPa, 0.93 +/- 0.05%) samples. The improvement in mechanical properties of the rolled samples were mainly attributed to the progressive elimination/reduction of inter-splat defects together with in-situ composite microstructure formation. EBSD and HRTEM revealed that in-situ composite structure was formed through progressive refinement and uniform distribution of Si particles in alpha-Al matrix containing coherent theta' precipitates. (C) 2018 Elsevier B.V. All rights reserved.

B4C particulate-reinforced 6061Al composite was fabricated by powder metallurgy method. The as-rolled composite possesses high tensile strength which is comparable to that of the peak-aged 6061Al alloy. More importantly, the microstructures and mechanical properties are thermally stable during long-term holding at elevated temperature (400 degrees C). The microstructual contributions to the strength of the composite were discussed. Transmission electron microscopy (TEM) analysis indicates that the in-situ formed reinforcement Mg(Al)Bs(2) as products of the interfacial reactions between B4C and the aluminum matrix. show not only good resistance to thermal coarsening but also strong pinning effect to the grain boundaries in the alloy matrix. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The paper aims to study influences of friction stir processing (FSP) on mechanical properties of Al2O3/B4C/Al composite. Al powder was ball-milled into flake powder and oxidized, then mixed with 10wt.% B4 Cparticles. The mixed powder was hot pressed, followed by being forged and FSPed. Mechanical properties at both high temperature and room temperature were tested. Compared with the forged samples, strength at room temperature of the FSP specimens was higher, whereas tensile strength of FSP did not increase at 375 °C. Al2O3 on grain boundary had significant effect on tensile properties at high temperature. FSP breaks up Al2O3 layers and disperses Al2O3 into grains, leading to weak pinning effect on grain boundaries. As a result, high temperature strength creases, but it is unfavorable to improving the high temperature performance.