Diffusion in FeNiCr alloys with an F.C.C. lattice

Abstract

The volume self-diffusion coefficients of 51Cr and 59Fe in 16 FeNiCr alloys with an f.c.c. lattice were measured using the modified Gruzin method in the temperature ranges 1298–1548 K for iron and 1286–1536 K for chromium. The self-diffusion coefficients, pre-exponential factors and activation energies for iron and chromium are tabulated. The concentration dependence obtained cannot be expressed by a simple mathematical relation; it is of higher order with a local minimum near the composition Fe-55 wt.%Ni-20 wt.%Cr. A critical analysis of the results obtained as well as previous knowledge made it possible to find the following relation between the self-diffusion coefficients of components which are valid over the whole temperature and concentration ranges examined: D Ni ∗: D Fe ∗: D Cr ∗ = 1:1.2:2 From the thermodynamic activity measurements, values of the thermodynamic diffusion factors in the ternary FeNiCr system and further values of the interdiffusion coefficients in this system were calculated. In this way a complete description of the diffusion processes in the ternary system was obtained. A comparison of the calculated interdiffusion coefficients with the experimental values found by other researchers was made.