Diffusion controlled stress rupture of polycrystalline materials

The high temperature stress rupture process in polycrystalline solids is examined in terms of grain boundary parting by vacancy condensation at the tip of a crack within the boundary. The gradient for diffusion of these defects is considered in the model to arise from the stress gradient in advance of the flaw tip. A rupture stress function is derived which is shown to closely describe the stress rupture behavior of a number of metals and high temperature alloys.