Interfacial Reaction of SiC/Fe-Cr Alloy

The microstructure of the reaction zone and the reaction kinetics of sintered α-SiC/Fe- 20Cr alloy annealed at 900℃ to 1150℃ were studied by using XRD, EMPA, SEM. The reaction zone can be divided into two sections of the SiC reaction zone and the metal reaction zone, according to the morphology and element distributions of the reaction zone of SiC/Fe-20Cr. The SiC reaction zone has high Fe and Si, but low Cr concentration, and it is composed of the bright matrix of Fe3Si, Cr7C3 and Cr3Si, and randomly distributed graphite precipitates. The metal reaction zone is a uniform region of (Cr,Fe)7C3, possessing very high Cr content. It is believed that the interface reaction is controlled by the atom diffusion through the reaction zone, and the reaction rate constant K is equal to 1.9×10-4exp(-235×103/RT)m2·s-1. The metal reaction zone hinders the interface reaction by inhibiting the diffusion of Fe atoms from the alloy towards the SiC reaction zone. The effect of the metal reaction zone can be improved with the increase of Cr content of the Fe-Cr alloys.