A transfer matrix method, developed recently by Ram-Mohan and Dayananda, was employed for the first time to generate error function solutions for quaternary diffusion in solid-solid metallic diffusion couples. The method was validated with the aid of a hypothetical couple with known quaternary interdiffusion coefficients and applied to two experimental Cu-Ni-Zn-Mn quaternary couples annealed at 775C. Quaternary interdiffusion coefficients were determined by the Dayananda analysis from the concentration profiles of the couples over selected composition ranges in the diffusion zone and employed for the subsequent transfer matrix method calculation of error function solutions. For the hypothetical test couple, identical sets of constant interdiffusion coefficients were determined on either side of the Matano plane and utilized for the calculation of concentration profiles via the transfer matrix method. For the experimental Cu-Ni-Zn-Mn couples, interdiffusion coefficients determined over selected regions in the diffusion zone were employed for transfer matrix method generation of the concentration profiles.

A Transfer Matrix Analysis of Quaternary Diffusion. K.N.Kulkarni, A.M.Girgis, L.R.Ram-Mohan, M.A.Dayananda: Philosophical Magazine, 2007, 87[6], 853-72