Microstructure and Mechanical Properties of AlSiTiCrNiCu Particles Reinforced Al6061 Composites by SPS and HPS Process

Three groups of AlSiTiCrNiCu high entropy alloy (HEA) particles reinforced Al606l composites were fabricated by spark plasma sintering at 520 and 570 °C (S520, S570) and by hot-pressed sintering at 570 °C(H570). The AlSiTiCrNiCu (AST) particles used as reinforcements were synthesized by mechanical alloying. The influences of the sintering process on the microstructure and mechanical properties of composites were investigated. The results showed that the AST particles had a near-equiatomic composition with a single BCC structure. The sintering temperature and time had a coupling influence on the interfacial microstructure. S520 had hardly reaction products and slight interfacial diffusion, and the AST particles were completely high entropy. Intense interfacial reactions happened on S570 and H570 with the same reaction products. The element diffusion of S570 was focused on the edge of the AST particles with partial loss of high entropy. Complete element diffusion and entire loss of high entropy of AST particles happened on H570. The differences in the microstructure caused by the three preparation methods led to the changes in mechanical properties and fracture mechanisms of composites.