Regularities of reaction diffusion and phase formation in the binary Ni-Bi, Ni-Zn, and Co-Zn systems

摘要

The layers of the intermetallics enriched in bismuth or zinc are the first to grow in reaction couples Ni-Bi, Ni-Zn, and Co-Zn. The formation of equiatomic phases of high symmetry is not observed. There is no even weak correlation between the growth rate of the layers of the intermetallic compounds and the width of their homogeneity range. The main factors determining the sequence of intermetallic-layer formation are the difference in the melting temperatures and atomic radii of the components as well as the crystal structure of the intermetallics. The Kirkendall effect is not observable with growing intermetallic layers. In this case, calculation of the integrated diousion coefficients has no physical grounds.