Diffusion-limited climb rate of a dislocation: Effect of climb motion on climb rate

The diffusion-limited climb rate of a straight dislocation immersed in a nonequilibrium concentration of point defects was calculated in the quasisteady-state approximation. It was shown that this approximation should apply in many cases of interest. Full account was taken of the effect of the dislocation climb motion while treating the problem of the diffusion of defects from (or to) the dislocation. The effect of the climb motion was expressed in terms of the dimensionless parameter vR/2D, where v is the climb velocity, R is the radius of the diffusion field of the climbing dislocation, and D is the point-defect diffusivity. For vR/2D«1, the effect of the climb motion was negligible. For vR/2D»1, the climb rate tended to be faster than that calculated by ignoring the climb motion. It was shown, however, that under usual conditions the climb motion could never be an important factor affecting the diffusion-limited climb rate. The results were applied briefly to some recent data for climbing dislocations in gold.