A phase field study of microstructural changes due to the Kirkendall effect in two-phase diffusion couples

The phase field method was used to simulate the interdiffusion in ternary, two-phase diffusion couples. Model γ+γ′ alloys were designed so that changes in the microstructure could be attributed to either coarsening or the Kirkendall effect. For the model parameters adopted in the study, particle coarsening increased the average precipitate size, but it had little influence on the diffusion path. However, the Kirkendall effect, which was introduced by setting atomic mobilities to different values, changed the diffusion path slope and led to the formation of “horns” on the two-phase diffusion path. Although the results obtained were somewhat dependent on the model parameters, they demonstrate the value of the phase field method when studying complex interdiffusion problems.