GRAIN-BOUNDARY SELF-DIFFUSION OF NI-63 IN AUSTENITIC NI-CR ALLOYS

The tracer diffusion of the isotope Ni-63 in Ni and three austenitic N i-Cr alloys containing 9.8, 20.1 and 29.1 wt.% Cr have been studied fr om 853 to 1203 K using a residual activity method. It appears that, wi thin the frames of experimental error, the activation enthalpy and pre -exponential factor do not depend on the composition of the alloys. Th e differences between the Arrhenius parameters obtained in this work f or Ni diffusion and the analogous parameters published earlier for the diffusion of Fe and Cr in Ni-Fe-Cr alloys were discussed in terms of Ni, Fe and Cr interaction with C impurities.