Interdiffusion between Ti 3SiC 2-Ti 3GeC 2 and Ti 2AlC-Nb 2AlC diffusion couples

Abstract

In this work, we report on the interdiffusion of Ge and Si in Ti3SiC2 and Ti3GeC2, as well as that of Nb and Ti in Ti2AlC and Nb2AlC. The interdiffusion coefficient, Dint, measured by analyzing the diffusion profiles of Si and Ge obtained when Ti3SiC2-Ti3GeC2 diffusion couples are annealed in the 1473-1773 K temperature range at the Matano interface composition (≈Ti3Ge0.5Si0.5C2), was found to be given by Dint increased with increasing Ge composition. At the highest temperatures, diffusion was halted after a short time, apparently by the formation of a diffusion barrier of TiC. Similarly, the interdiffusion of Ti and Nb in Ti2AlC-Nb2AlC couples was measured in the 1723-1873 K temperature range. The Dint for the Matano interface composition, viz. ≈(Ti0.5,Nb0.5) 2AlC, was found to be given by At 1773 K, the diffusivity of the transition metal atoms was ≈7 times smaller than those of the Si and Ge atoms, suggesting that the former are better bound in the structure than the latter. © 2007 The American Ceramic Society.