Reinforcing Al matrix composites by novel intermetallic/SiC interface and transition structure

Abstract

Interfacial bonding has attracted extensive attention because it essentially affects the performance of SiC reinforced Al matrix composites. To investigate the impact of Ni and Cu inherent in the Al matrix on the interfacial bonding of the composite, Al–Si–Mg/oxidized SiC composite and Al–Si–Cu–Ni–Mg/unoxidized SiC composite were fabricated by semisolid stir casting. Our study demonstrated that several intermetallics can nucleate and grow on the surface of SiC in Al–Si–Cu–Ni–Mg/unoxidized SiC composite during solidification, forming the intermetallic/unoxidized SiC interface and Al-intermetallic-SiC transition structure. The bonding of the Al3CuNi/unoxidized SiC interface is stronger than the conventional Al/oxidized SiC interface. The Al3CuNi/unoxidized SiC interface is functional in impeding crack propagation and withstanding loading during deformation. Moreover, the Al-intermetallic-SiC transition structure can alleviate the agglomeration of SiC particles, improve the overall coherency and coordinate the deformation of the composite. The extraordinary interface and structure strengthen the composite to a certain extent both at room and high temperatures.