Atomic mobilities and diffusivities in fcc_A1 Ni–Cr–V system: Modeling and application

Abstract

Ni–Cr–V system is a significant sub-system of both cemented carbides and superalloys. In the present work, the atomic mobilities for fcc_A1 Ni–Cr–V alloy were evaluated by means of the CALTPP (CALculation of ThermoPhysical Properties) program, which utilizes the thermodynamic description and the interdiffusivity obtained in our previous work by a numerical inverse method. The reasonability was validated through comparing the CALTPP-predicted composition profiles, interdiffusivities and diffusion paths with the experimentally measured ones. Furthermore, in order to study the diffusion behaviors, the present atomic mobilities were applied to calculate the diffusion fluxes, the interdiffusivities over the whole investigated composition and temperature ranges, the pre-frequency factors as well as the activation energy. It can be seen from the 3-dimensional interdiffusivity planes that when the composition of Cr is more than that of V, the diffusion of Cr is generally faster than V. The pre-frequency factor indicates that the frequency of collisions between Cr atoms is higher than that of V while the activation energy shows that the diffusion of Cr requires more energy than V. The presently obtained diffusion characteristics of fcc_A1 Ni–Cr–V alloys are critical for predicting and controlling the microstructure evolution and further designing high-performance cemented carbides as well as superalloys.