Ternary diffusion in fcc phase of Fe-Ni-Cr alloy system at 1223 K

Abstract

The ternary charmical diffusion has been studied in the iron-nickel-chronium system in the gamma phase at the temperature of 1223 K. The concentration penetration profiles of the diffusing elements have been established employing an electron probe microanalyser. The major and cross diffusion coefficient have been evaluated using the Boltzmann-Matano method as extended to the ternary system. The major diffusion coefficients are positive, while the cross diffusion coefficients are negative. The concentration denpendence of diffusion coefficients has been rationalised and can be expressed as the function of concentrations of nickel and chromium. The interaction parameters have been estimated from the variation of ratio of the major to cross diffusion coefficients with concentrations. The estimated interaction parameters indicate that the diffusive interaction between nickel and iron is much stronger than that between chromium and nickel or chromium and iron. Tracer diffusion coefficients have been estimated from the ternary diffusion coefficients and are in the order DCr > DFe > DNi. Intrinsic diffusivities have also been evaluated.