Interfacial structure and stability of a co-continuous SiC/Al composite prepared by vacuum-pressure infiltration

The interfacial structure of a SiC_3D/Al composite prepared by vacuum-pressure infiltration was investigated to determine whether interfacial reactions occur and specific orientation relationships exist between SiC and Al. The resulting SiC/Al interfaces were continuous and free of any precipitates and voids. There is no consensus for the orientation relationship between 6H-SiC and Al. In addition, the mismatch between the two phases at the interface was accommodated by mismatch dislocation. The stability of the SiC_3D/Al composite after annealing at 873 K for 10 h was determined. No Al₄C₃ precipitated at the interface, although grain coarsening of Al occurred. Compared with the concentration gradients at the initial interfaces, those obtained at the interface after annealing were still steep, indicating that concurrent interdiffusion occurred between SiC and Al in a very narrow region near the interfaces. Theoretical calculations suggest similarly the chemical and structural stability of the SiC/Al interface during the annealing treatment.