High-throughput determination of interdiffusivities and atomic mobilities in Fcc Co-Ni-V alloys

Accurate diffusion kinetics of Co-Ni-V medium entropy alloys can guide alloy composition and process design, facilitating further exploration of their performance potential. Totally twelve diffusion couples close to the Co-Ni binary side were assembled, and their composition profiles were measured by EPMA to determine the diffusivity of Fcc Co-Ni-V alloys at 1273, 1373 and 1473 K. The interdiffusivities along the whole composition profiles and the atomic mobilities of Fcc Co-Ni-V alloys were evaluated by the numerical inverse approach incorporated in CALTPP program (CALculation of ThermoPhysical Properties). The obtained interdiffusivities were further compared with those calculated by the Matano-Kirkaldy method, which can accurately determine the diffusivities at the intersection compositions of two diffusion paths. Meanwhile, the model-predicted composition profiles and diffusion paths of Co-Ni-V alloys show good agreements with the experimental ones, validating the accuracy of the presently obtained atomic mobilities. Furthermore, the presently assessed atomic mobility parameters coupled with thermodynamic description of Fcc Co-Ni-V alloys were applied in calculating interdiffusivities, activation energies and frequency factors.