Diffusion coefficients of the multicomponent β-NiAl phase at 850, 950 and 1050C were estimated as a function of composition by means of analyzing interdiffusion fluxes from concentration profiles which were obtained from the pack-aluminizing diffusion couples. The results indicate that values of DAlNiint and DAlCoint were strongly composition dependent and values of DAlCrint were slightly composition-dependent. There exist significant differences in values of DAlNiint between those obtained in this study and those reported in the literature for the binary NiAl phase. These differences become larger as the temperature decreases. This could be explained by the variation of the thermodynamic properties of the multicomponent β-NiAl phase, which results from the solid solution of the alloying elements present in the nickel-based superalloy. The changes in the electronic structure due to the atomic size mismatch between the solute and solvent atoms may partially be responsible for these differences.

On Interdiffusion in the Multicomponent β-NiAl Phase. H.Wei, H.Y.Zhang, G.C.Hou, X.F.Sun, M.S.Dargusch, X.Yao, Z.Q.Hu: Journal of Alloys and Compounds, 2009, 481[1-2], 326-35