Diffusion of Chromium in Nickel

Abstract

Diffusion of chromium in pure nickel has been studied by radioactive tracer and residual activity technique. The diffusion coefficient (in units of cm2/sec) in the range 600°−900°C is given by DCr/Ni=0.03 exp(−40 800/RT) and in the range 350°−600°C is given by DCr/Ni=5.45×10−9 exp(−13 700/RT). The bimodal diffusion behavior has been explained on the basis of solid solubility of chromium in nickel, which falls very rapidly from 1000°C downwards. The entropy of activation for high-temperature diffusion falls very well on the entropy vs activation energy curve for lattice diffusion in nickel.