Fabrication of Cu–Al MMC with randomly-oriented continuous intermetallic layers via entangled twisting fiber plasma sintering

A novel solid-state fabrication route, termed entangled twisting fiber plasma sintering (ETFPS), is introduced for producing Cu–Al metal matrix composites (MMCs) with enhanced interfacial bonding and superior mechanical performance. Twisted Cu and Al fibers were entangled and consolidated by spark plasma sintering, forming a three-dimensionally interconnected network of randomly-oriented continuous intermetallic layers (RoCIMCs). This configuration promotes isotropic load transfer, strong metallurgical connectivity, and uniform phase distribution across the composite. Microstructural analysis revealed two intermetallic phases, Al2Cu adjacent to the Al side and Al4Cu9 nearer the Cu side, formed through diffusion-controlled reactive growth, where the higher diffusivity of Cu in Al favored sequential phase evolution. Also, microstructural analyses (OM, SEM, EDS) confirmed continuous IMC layers with an average thickness of ∼10 μm. The results of compression testing indicated that the Cu–Al composite reached a yield strength close to 170 MPa and an ultimate strength of around 432 MPa, nearly 1.7 times that of pure Cu. The hardness was markedly higher than that of Cu–Al composites produced via powder sintering or accumulative roll bonding. The ETFPS method therefore provides a new pathway for controlling intermetallic formation and orientation in MMCs, leading to simultaneous improvements in strength, hardness, and structural stability.