Concepts for estimating all types of diffusion coefficients of NiCoFeCr multi-principal element alloys using two dissimilar or a combination of ideal and non-ideal pseudo-ternary diffusion couples

Abstract

The estimation of diffusion coefficients in multicomponent system is facilitated by strategically designing diffusion couples with constrained diffusion paths. We have demonstrated methods of estimating tracer diffusion coefficients following three different combinations of diffusion profiles: (i) By intersecting a pseudo-ternary diffusion path with a rectilinear pseudo-binary diffusion path, (ii) by considering a combination of two dissimilar pseudo-ternary diffusion paths, and (iii) considering a combination of ideal and non-ideal pseudo-ternary diffusion paths with uphill diffusion characteristics. Equation schemes required for such analyses depending on the type of diffusion profiles are explained in detail. This approach relies on the availability of reliable thermodynamic data for the estimation of the tracer diffusion coefficients. Following, as demonstrated, one can calculate the intrinsic and interdiffusion coefficients of all the elements for a conventional diffusion couple in which all the elements would produce the diffusion profiles.