Interdiffusion in Two-Phase Ternary Solid Systems.

摘要

The pseudo-binary approach to diffusion in two phase ternary systems is discussed. In particular, the circumstances under which virtual diffusion paths arise are highlighted. Despite the imprecision inhererrt in virtual paths, it is recognised that they have an advantage over, so-called, real paths (which simply run along phase boundaries) in that they include information about the relative proportions of the phases present in two-phase regions. The term Composite Diffusion Path is introduced, which retains this advantage of a virtual path, but avoids its short-comings by not being based on the assumption of pseudo-binary behavior. The composite diffusion paths are derived from first principles for two model diffusion couples, each comprising a single phase ((alpha)) alloy annealed in contact with a two phase ((alpha)+(beta)) alloy. Comments are also made on the interrelationship between diffusion coefficient data and the shapes of phase boundaries in ternary systems, results being presented which suggest that conclusions about one can be made on the basis of information about the other.