Interdiffusion paths in the diffusion couple Ti-SiC

Thermochemical calculations and considerations have been applied to describe the interdiffusion and formation of interface phases in the diffusion couple Ti-SiC for the case of a thin Ti layer on a SiC substrate. With the aid of activity diagrams and relevant thermochemical calculations possible diffusion paths are discussed and their progress simulated. It is shown that the emergence and disappearance of TiC 1-x during interdiffusion can be interpreted thermochemically. TiC 1-x and Ti 5 Si 3 C x appear as initial phases to be joined later by Ti 3 SiC 2 . Then TiC 1-x and Ti 5 Si 3 C x disappear and TiSi 2 emerges. The final decomposition of TiSi 2 and Ti 3 SiC 2 can either take place with excess carbon available from the substrate or the gas phase or by simultaneously abstracting silicon from the system. In both cases TiSi 2 decomposes first, followed by Ti 3 SiC 2 . Besides SiC, only (Ti, Si)C 1-x is then left as a stable compound.