The bulk diffusivity of Mo in austenitic steels was measured by using the sandwich method (table 66). It was found that the Mo interdiffusion coefficient was independent of the Mo content (for steels with 12 to 19wt%Cr, 12 to 16wt%Ni, up to 2wt%Mo, and up to 0.27wt%N) at temperatures of between 1283 and 1523K. The diffusivity of Mo was higher than that of Cr, Ni or Fe. The Mo diffusion parameters were decreased by adding up to 0.25wt%N. The latter effect was attributed to lattice expansion or to an increasing vacancy concentration. Small variations in the initial Cr and Ni contents had a negligible effect upon the absolute values of the Mo diffusivity.

A.Kühl, D.Bergner: Materialwissenschaft und Werkstofftechnik, 1991, 22[8], 316-9

Table 66

Diffusion Parameters for Mo in Fe-Cr-Ni-Mo Alloys