LII. Grain boundary diffusion in metals

Abstract

Abstract By an extension of a recent analysis of the problem of grain boundary diffusion in metals, the expression has been derived relating the diffusion coefficients D′ and D for grain boundary and for volume diffusion, δ the effective “ width ” of the grain boundary and α the angle at time t between a line of constant concentration and the grain boundary at the point where it meets the grain boundary. Some remarks are made on the use of the equation and when it is applied to a recent experimental observation on grain boundary diffusion of copper in nickel, the result is deduced that D′ = 8 cm.2/day at 1000°C. A discussion follows on some aspects of the relation of other work on grain boundaries to grain boundary diffusion. Evidence is presented, based on models of the grain boundary, which suggests that the activation energies for grain boundary and for volume diffusion may not differ appreciably.