Diffusion of ⁶⁰Co in dilute V-Co alloys

Abstract

Impurity diffusion of cobalt in vanadium was measured at five concentrations including the zero cobalt concentration. The activation energies measured in these alloys are in the range 293–226 kJmol⁻¹ for zero and 2 at.% cobalt, respectively. The impurity enhancement observed in these alloys was analysed by linear, polynomial and exponential functions which relate the diffusivity of the solute to its concentration. It seems that the higher terms in the concentration of the polynomial function cannot be neglected in the case of Co diffusion in vanadium. A relation for the temperature dependence of the enhancement factor B is given either as

or as

where the pre-exponential terms and the difference in the activation energies are defined as

The quantities in parenthesis refer to some concentration c and zero concentration, B ₁ values for some b.c.c. systems are indicated in the illustrations.