A new modification of Dayananda's method was proposed that permitted the evaluation of the concentration-dependence of diffusion matrix elements, D̃ijNi, using only one diffusion couple. The procedure was applied to interdiffusion in γ'-Ni3Al-X (X = Cr, Fe, Nb, Ti) at 1173 to 1533K (figure 9). It was found that the activation enthalpy, QXXNi, and the frequency factor, DoNiXX, decreased with increasing concentration of X. In the limit cx → 0, the values of D̃NiXX approached the literature values of tracer diffusion coefficients of X in Ni3Al. An estimation of the Al so-called tracer diffusion coefficient in Ni3Al was obtained that was in reasonable agreement with other published estimates. With decreasing concentration of X in Ni3Al, the difference between the Arrhenius parameters QXXNi, DoXXNi and respective values of QXXNi and DoNiAlAl decreased. The QXXNi and DoXXNi agreed with values reported in the literature for very dilute solution of X in Ni3Al.

Ternary Interdiffusion Coefficients in Chosen Ni3Al-Based Alloys. Cermak, J., Rothova, V.: Defect and Diffusion Forum, 2005, 237-240[1], 83-94