The γ’ single phase interdiffusion in Ni3Al–X (where X was Cr, Fe, Nb or Ti) was studied at 1173 to 1533K. The elements of the diffusion matrix, DijNi, were estimated by using a modification of Dayananda’s method which permitted the evaluation of their concentration dependence by using only one couple. It was found that the activation enthalpy, QxxNi, and the frequency factor, DoxxNi, decreased with increasing concentration of element X. In the limit of cx → 0, the values of DxxNi approached the published values of the tracer diffusion coefficients of X in Ni3Al. An estimation of the so-called Al 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 Arrhenius parameters QxxNi, DoxxNi and respective values of QAlAlNi and DoAlAlNi decreased. QxxNi, DoxxNi agreed with values reported in the literature for very diluted solution of X in Ni3Al.

Concentration Dependence of Ternary Interdiffusion Coefficients in Ni3Al/Ni3Al–X Couples with X = Cr, Fe, Nb and Ti. Cermak, J., Rothova, V.: Acta Materialia, 2003, 51[15], 4411-21

Figure 10

Diffusion of Cu, Fe and Si in Ni3Al