Diffusion Behaviour in Ternary, Multiphase Systems

Abstract

The theory of diffusion in ternary systems and observations on a series of multiphase diffusion couples in the system Cu-Zn-Sn are used to develop a group of seventeen general theorems or rule s pertaining to the construction of diffusion paths on a ternary isotherm.The concept of the “virtual” path is introduced as an aid to path prediction in multiphase systems. It is found that there may be many path configurations that satisfy the diffusion and boundary conditions so that thermodynamic variational methods are required for unique specification. Experimentally, there appears to be a natural preference for high-resistance series configurations, an observation that is qualitatively consistent with the principle of minimum entropy production.