Interdiffusion coefficients and atomic mobilities in the bcc phase of the Ti-Fe-Mo system

Establishing the atomic mobility database for the Ti-Fe-Mo system is essential for analyzing and simulating diffusion-controlled processes in novel low-cost biomedical titanium alloys. In this study, twelve sets of diffusion couples were prepared at annealing temperatures of 1273 K, 1323 K, and 1373 K, with annealing time of 24 h, 10 h, and 6 h, respectively. The compositional distance profiles at the diffusion couple interfaces were measured using an Electro Probe Micro-Analysis (EPMA). Numerical inverse methods were applied to calculate diffusion coefficients in a high-throughput method, complemented by the Matano-Kirkaldy approach to determine diffusion coefficients at diffusion couple intersections. The results from both methods demonstrated strong agreement. Based on accurate thermodynamic descriptions and diffusion coefficients, the kinetic parameters of the Ti-Fe-Mo sub-binary systems were re-evaluated. Using HitDIC software in conjunction with compositional distance profiles, the atomic mobility database for this system was ultimately established. Additionally, the frequency factor and activation energy, vary with composition, can be derived using the Arrhenius equation.