Kinetic modeling of β-BCC phase in Ti-Al-Nb system in the temperature range of 1060-1200 °C

Mobility parameters of constituents in beta-BCC phase of binary Al-Nb are optimised in the temperature range of 1350-1550 degrees C followed by ternary Ti-Al-Nb optimisation in the range of 1060-1200 degrees C. PARROT module of DICTRA is employed for optimisation by fitting against the experimental diffusion coefficients. Calculated binary (D) over bar (Al-Nb), lie within +/- 50% error window, which is less than the typical experimental uncertainties involved in interdiffusion analysis. In the ternary system of Ti-Al-Nb, main interdiffusion coefficients show better fit with the respective experimental values than the cross terms. Concentration profiles and diffusion paths were computed for various diffusion couples studied in BCC Ti-Al-Nb system at three different temperatures using the optimised parameters. These diffusion profiles were found to be in good agreement with the experimental ones, thus verifying the validity of the optimised parameters.