Abstract
Interdiffusion in Ni-Cr (fcc phase) alloys with small additions of Al, Si, Ge, or Pd was
investigated using solid-to-solid diffusion couples. Ni-Cr-X alloys having compositions of Ni-
22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-
22at.%Cr-1.6at.%Pd were manufactured by arc-casting. The diffusion couples were assembled in
an Invar steel jig, encapsulated in Ar after several hydrogen purges, and annealed at 900�C in a
three-zone tube furnace for 168 hours. Experimental concentration profiles were determined
from polished cross-section of these couples by using electron probe microanalysis with pure
element standards. Interdiffusion fluxes of individual components were calculated directly from
the experimental concentration profiles, and the moments of interdiffusion fluxes were examined
to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on
the diffusional behavior of Ni-Cr-X alloys are presented in the light of the diffusional
interactions and the formation of a protective Cr2O3 scale