The interdiffusivity matrices in fcc_A1 Ni–Cr–V alloys: A high-throughput evaluation by CALTPP program

Abstract

The accurate interdiffusivity for fcc_A1 Ni–Cr–V system is needed for simulating the microstructure evolution for Ni-based alloys. In order to determine the interdiffusivity, totally fifteen diffusion couples bound with fcc_A1 Ni–Cr–V alloys were prepared in the present work. Both EPMA (Electron Probe Micro-Analysis) and XRD (X-ray diffraction) results can verify that all the samples are of fcc_A1 single phase. The composition profiles of each diffusion couple annealed at 1273, 1373 and 1473 K were measured by EPMA and then were fitted by Boltzmann function. Applied the fitted composition profiles to Matano-Kirkaldy method, the interdiffusivities at the intersection points of every two diffusion paths were obtained. All of the obtained interdiffusivities can satisfy the constraints of the thermodynamic stability. Moreover, in order to obtain the composition-dependent interdiffusivity, two types of the numerical inverse method implemented in a recently developed CALTPP (CALculation of ThermoPhysical Properties) program were utilized in the present work. Both methods can result in consistent composition profiles in comparison with the measured ones and can produce interdiffusivities in good agreements with the ones by Matano-Kirkaldy method. Both methods have advantages which can be selected flexibly. In the present work, the pure mathematical method was recommended due to its higher accuracy.