AVERAGE EFFECTIVE INTERDIFFUSION COEFFICIENTS AND THE MATANO PLANE COMPOSITION

From an integration of the interdiffusion flux of a component over dis tance in the diffusion zone of an isothermal solid-solid diffusion cou ple, average effective interdiffusion coefficients can be evaluated ov er selected ranges of composition. An analysis is developed to inter-r elate, in general, the average effective interdiffusion coefficients c alculated for the composition ranges on either side of the Matano plan e to the composition at the Matano plane. Characteristic depths for co ncentration profiles on either side of the Matano plane are employed t o characterize the concentration profiles and their deviations from er ror function solutions. The analysis is applied to the concentration p rofiles of a binary Fe-C as well as a ternary Cu-Ni-Zn single-phase di ffusion couple. From a knowledge of concentration profiles on one side of the Matano plane, profiles on the other side can be generated from an error function model based on the analysis.