Diffusion of Ni 63 and Cr 51 in Nickel-Chromium Alloys (On the Relation between High-Temperature Creep and Diffusion in Nickel Base Solid Solutions. I)

Abstract

Self-diffusion coeffs. of Ni and Cr in Ni-Cr alloys contg. 0-30 at. % Cr were measured with a usual lathe sectioning technique at 1040-1300°. Polycryst. specimens having 1-4 mm. grain size were used. In all alloys examd., Cr atom diffused more rapidly than Ni atom, and the ratio of diffusion coeff. of Cr to that of Ni was about 1.6 independent of the Cr content over the whole temp. range. Diffusion rates of both elements decreased slightly with increasing content of Cr. The frequency factors for Ni self-diffusion are 1.9, 3.3, 1.6, and 2.9 cm.2/sec., and the activation energies are 68.0, 70.2, 68.5, and 70.5 kcal./mole in alloys contg. 0, 10.0, 19.9, and 29.7 at. % Cr, resp. For Cr self-diffusion in the resp. alloys the frequency factors are 1.1, 1.4, 1.9, and 3.2 cm.2/sec., and the activation energies are 65.1, 66.5, 67.7, and 69.4 kcal./ mole.