Segregation During Diffusional Creep of a Binary Solid Solution

In the diffusional creep of a substitutional solid solution where the diffusivities of the components are different, there is a transient state in which the vacancy flux uses preferentially those atoms with the higher diffusivity, producing segregation of the components. A mathematical formulation of steady-state diffusional creep of a multicomponent solid solution is obtained and, by using a onedimensional model of diffusional creep, the amount of segregation required to achieve the steady state in a binary solution is evaluated in terms of either the activity coefficients or the thermodynamic factor. A simple rule of thumb to evaluate the amount of the segregation is given and results for ideal and regular solid solutions are obtained.