Diffusivity and atomic mobility for fcc Ni–Cu–Ti alloy: Measurements and an intelligent modeling

The diffusivities of fcc Ni-rich Ni–Cu–Ti alloy have been systematically investigated by means of experimental measurements and an intelligent modeling. Utilizing two bulk diffusion couples without intersection points in diffusion paths together with electron probe microanalysis technique, the interdiffusion coefficients along the whole diffusion path in fcc Ni–Cu–Ti alloy at 1273, 1373 and 1473 K are determined by a novel numerical inverse method. Three new diffusion couples together with two initial diffusion couples are used to obtain the diffusivities by Matano-Kirkaldy method. Two sets of atomic mobilities are established based on the interdiffusion coefficients obtained using numerical inverse method and Matano-Kirkaldy method, respectively, through an intelligent modeling in CALTPP (CALculation of ThermoPhysical Properties) program. The reliability of present two sets of atomic mobilities is verified by comprehensive comparisons between the calculated and experimental properties, including diffusivities, concentration profiles and diffusion paths. A preferable agreement is found in the comparisons where the diffusivities are calculated using numerical inverse method. The present investigation of diffusivities for fcc Ni–Cu–Ti alloy demonstrates that two diffusion couples combined with the numerical inverse method can establish a reliable atomic mobility for the targeted alloys.