Diffusion behaviors of BCC_B2 phase in Ni-Ti-Fe ternary system

High-throughput determination of the diffusion coefficients in the BCC_B2 phase of Ni-Ti-Fe shape memory alloys provides essential input parameters for multiphysics simulations, such as phase-field modeling, DICTRA simulations, and ICME-guided alloy design. In this study, 11 sets of diffusion couples were prepared and annealed at 1223 K, 1273 K, and 1323 K for 60 h,48 h, and 36 h, respectively. Composition-distance profiles at the diffusion interfaces were measured by Electron Probe Microanalysis. Interdiffusion coefficients were extracted via numerical inverse method, and the results were compared with those obtained by the traditional high-accuracy Matano–Kirkaldy method. The results of the two methods show strong consistency. Both composition-dependent and distance-dependent interdiffusion coefficients were established. Furthermore, the composition-dependent variations of the frequency factor and activation energy was evaluated based on the Arrhenius equation. These results offer a comprehensive insight into the diffusion behavior of the Ni-Ti-Fe system, providing critical data for kinetic modeling and alloy optimization.