Diffusivities and atomic mobilities for fcc Cu-Ni-Sn alloys

Utilizing five groups of bulk diffusion couples together with electron probe microanalysis technique, the composition-dependent ternary interdiffusion coefficients in fcc Cu-Ni-Sn alloys at 1023 K were determined via the Whittle and Green method. The presently obtained interdiffusion coefficients at 1023 K as well as our previously measured ones at 1073 K were combined with the slightly modified thermodynamic descriptions of the fcc Cu-Ni-Sn phase to explore atomic mobilities of Cu, Ni and Sn in fcc Cu-Ni-Sn alloys within the CALPHAD framework. In order to be consistent with the thermodynamic description, atomic mobilities in binary fcc Ni-Sn alloys were re-evaluated in the present work. The quality of the assessed kinetic characteristics was confirmed by the comprehensive comparisons between various model-predicted diffusion behaviors and the experimental ones, including concentration profiles and diffusion paths.