On Diffusion in the Β-Nial Phase

Interdiffusion coefficients in the β-NiAl phase over the homogeneity range are determined by the diffusion couple technique in the temperature range of 1000–1200°C. Intrinsic diffusivities of the species at 1000°C at different compositions are measured by Kirkendall marker experiments. The variations of the molar volume with composition and partial molar volumes of the species, required for the determination of the diffusion parameters, are calculated using lattice parameter and vacancy concentration. Tracer diffusion coefficients of the species were calculated from the knowledge on intrinsic diffusivities and compared with the data available in the literature, which were measured directly by tracer methods. The influence of the vacancy wind effect is determined on the calculated results.