Single-phase interdiffusion in intermetallic compound CoTi

Intermetallic compounds have recently attracted much attention as practical materials. Although much effort has been devoted to understand mechanical properties, investigations on diffusion in intermetallics are relatively scarce. The knowledge of diffusion behavior is of interest for production of these materials and for their practical use. Interdiffusion data are available in the literature of CoTi. However, the data were determined from multiphase diffusion couples and the measured interdiffusion data are more or less effective diffusion coefficients, because inherent interfacial reaction could not be excluded in the diffusion process. Therefore, interdiffusivity in intermetallic compounds should be determined from diffusion experiments using single-phase interdiffusion couples. CoTi fulfills the necessary requirements for single-phase interdiffusion, since the intermetallic compound has a wide homogeneity range and is sufficiently ductile to prepare diffusion couples by welding. The present paper reports the result of the interdiffusivity measure in B2-type intermetallic compound CoTi.