Critical Grain Size/Preexisting Flaw Size Relations in Anisotropic Brittle Solids

Abstract

A known solution for the critical condition of thermoelastic microcrack initiation is adopted to evaluate the extent of crack propagation after initiation and the arrest condition. It is shown that the critical temperature for crack initiation and the strength of thermoelastically anisotropic polycrystalline materials is not determined by the grain size only but also by the ratio of grain‐to‐flaw size. The variation of slopes in the strength‐grain size plot is interpreted in terms of preexisting annular flaw‐size change. The major implications of the analysis are discussed in relation to experimental results on a number of polycrystalline ceramics.