Interaction of cavitating grain boundary facets in creeping polycrystals

A plane strain unit cell model containing a periodic array of hexagonal grains is used to analyse creep fracture in polycrystalline metals at elevated temperatures, taking into account the effect of sliding at all grain boundaries. The grains deform elastically and by power law creep, and the possibility of cavity nucleation and growth at the grain boundaries is incorporated. For a single cavitating grain boundary facet, or a single facet microcrack, the effect of microcrack density or spacings is studied by varying the number of grains in the unit cell or the aspect ratio of the unit cell. In cases where creep constrained cavitation develops, and for open microcracks, a significant effect of crack density and cell aspect ratio is found. The multi-grain unit cells are also used to study the influence of nonuniform distributions of cavitating facets such as facet clustering, where strong interaction between neighbouring cavitating facets tends to develop.