Interdiffusivity matrices and atomic mobilities in fcc Ni-Fe-Mo alloys: Experiment and modeling

Accurate diffusivities in fcc Ni-Fe-Mo alloys are of significant importance in designing high-quality magnetic alloys. In this work, totally twelve fcc single-phase diffusion couples are assembled to determine the diffusivities of fcc Ni-Fe-Mo alloys at 1373, 1423 and 1437 K. The diffusivity matrices at the intersection compositions of diffusion paths are determined by the Matano-Kirkaldy method. In addition, the diffusivity matrices along the whole composition profiles of individual diffusion couple and the atomic mobilities of fcc Ni-Fe-Mo alloys are evaluated by the numerical inverse approach incorporated in CALTPP program. The reliability of the obtained atomic mobilities is verified by comparing the predicted diffusion behaviors with the experimental ones. Furthermore, applying the presently obtained atomic mobilities in combination with thermodynamic descriptions, the three-dimensional maps of interdiffusivites, activation energy and frequency-factor planes of fcc Ni-Fe-Mo alloys are constructed to display the composition- and temperature-dependent diffusion properties. The presently obtained diffusivities and atomic mobilities of the Ni-Fe-Mo fcc phase are expected to contribute to high-efficiency Ni-Fe-Mo magnetic alloy design.