The climb of dislocations which are connected to bubbles and voids

Abstract

The theory of the climb mobility of a dislocation connected to an array of bubbles or voids is developed. When climb occurs by lattice diffusion, the most important feature is the resolved force exerted by the dislocation on the bubble or void. The climb velocity may then be controlled by bubble or void drag under certain conditions. If diffusion can occur along the core of the dislocation, the behaviour is more complex. The vacancy flux along the core can lead to growth or shrinkage of the bubble or void, depending on the sign of the stress. The velocity can then change with climb distance in a way that depends on the bubble or void size. For bubbles, the size changes are accompanied by internal pressure changes and this feature can give rise to reversible effects following a stress change. For a void, there is no internal gas pressure, so that the surface tension can drive climb even in the absence of an applied stress. These aspects are quantified and conditions defined where they are likely to be important in practice.