Kinetic modeling of the γ phase in Ti-Al-Nb alloys

A mobility database for the γ-TiAl phase in the Ti-Al-Nb system was created by a critical assessment of experimental diffusion data found in literature. Optimization of mobilities and diffusion modeling was performed using the DICTRA (DIffusion Controlled TRAnsformations) software. Agreement was found between the experimental and calculated diffusion coefficients. The database was further validated with a diffusion couple consisting of 46Ti-54Al and 31Ti-55Al-14Nb alloys. The experimental data and final optimization revealed Nb-dependent effects on the diffusivities of all three elements. The Nb diffusivity increases with Nb content, and the Ti and Al diffusivities vary with composition in both binary and ternary alloys.