Atomic mobilities, diffusion coefficients, and kinetic coefficients in Ti-rich Ti-Mo-Nb system

Diffusion coefficient is an important physical property to control the microstructure, thus the establishment of atomic mobility databank for Ti-based alloy systems is vital to the design of novel Ti alloys. In the present work, ternary Ti-Mo-Nb diffusion couples within the single bcc phase were prepared and measured after annealing at 1273 K for 25 h, and interdiffusion coefficients of bcc Ti-Mo-Nb alloys at 1273 K were determined from the experimental composition profiles by using Matano-Kirkaldy method. Subsequently, the atomic mobility parameters of bcc Ti-Mo-Nb system under the CALculation of PHAse Diagrams (CALPHAD) framework were assessed by using recently proposed diffusion models, which were verified by the comparisons between the experimental interdiffusion coefficients/composition profiles and the model-predicted results. Moreover, diffusion models were carefully discussed for the ternary assessment. Finally, relationships among atomic mobility, kinetic coefficient, and diffusion coefficients were discussed and demonstrated via ternary contour maps. The present work contributes to the development of diffusion databank for computational design of biomedical Ti alloys.