Ternary Interdiffusion Coefficients in BCC Ti-Al Based Alloys and Their Application in Simulations of Homogenization and Finite Diffusion Couples

Interdiffusion data have gained utmost significance for predictive alloy design and process development with ever-increasing utilization of integrated computational materials engineering (ICME), Artificial Intelligence (AI) and Machine Learning (ML) in automobile industry. Titanium-Aluminium based alloys have great potential as lightweight alternative for steels. Hence, a review of interdiffusion studies reported in the β phase field of Ti-Al based ternary systems is presented. Availability of a variety of diffusivity terms at times create confusion in the users’ minds. Hence, the review starts with a brief discussion on some basic concepts in diffusion. Significance of diffusional interactions is specifically emphasized in this review as observed in the several Ti-based systems reviewed here. New analytical expressions are presented for evolution of concentration profiles in multicomponent systems for two types of boundary conditions, one for periodic boundary conditions typically observed in homogenization process and another for diffusion couples with finite boundary conditions. The newly derived expressions are then used for simulating concentration profiles in two hypothetical ternary systems, mimicking Ti-Al-Fe and Ti-Al-Nb. The simulation results clearly bring out the fact that diffusional interactions in these ternary systems can be effectively utilized to selectively enhance or deplete certain regions of a particular component by appropriately setting up the relative concentration gradients of the diffusing species.