Diffusivities and atomic mobilities in fcc Co–Cu–Mn alloys

Accurate diffusivities and atomic mobilities of fcc Co–Cu–Mn alloys are essential for developing novel high-entropy alloys. However, no ternary interdiffusion information of Co–Cu–Mn alloys is available in the literature. Twelve diffusion couples are prepared to determine the diffusivities in fcc Co–Cu–Mn alloys at the temperature ranges from 1373 to 1473 K. Two versions of diffusivity matrices are determined by the Matano-Kirkaldy method (version 1) and numerical inverse approach (version 2), respectively. And their corresponding atomic mobilities are extracted in CALTPP. The good consistency of the two versions of diffusivities demonstrates the reliability of diffusivities extracted by the numerical inverse approach. Further comparisons show that the numerical inverse approach can determine the diffusivities more efficiently, provide more composition-dependent diffusivities and obtain more reliable atomic mobilities than the Matano-Kirkaldy method. The atomic mobility parameters of version 2 are further used to construct the three-dimensional interdiffusivity matrix of the fcc Co–Cu–Mn system. The presently obtained kinetic parameters are key inputs for the computational design of high-entropy alloys.