Wedge crack growth enhanced by vacancy diffusion under creep conditions

Abstract
The creep failure of polycrystalline materials is discussed in terms of a grain boundary sliding mechanism. In the proposed model wedge cracks are nucleated due to grain boundary sliding at triple point junctions. The resulting stable cracks grow to a critical size by further boundary sliding and by diffusion of vacancies to the defects. A failure condition is given which relates the time to fracture to the creep rate, temperature and diffusion characteristics of the material.