Strength‐Grain Size Relations in Polycrystalline Ceramics

A model is presented to explain the strength-grain size behavior of ceramics exhibiting duplex microstructures and of ceramics with uniform coarse-grained microstructures. Using an energy balance analysis, the model shows that in most ceramics an hitiipl flaw contained within a single large grain will initially propagate and then arrest after entering the region of increased fracture-surface energy. The arrested flaw will subsequently propagate to failure at the value OF the critical stress intensity factor. Using the data in the literature, a strength-(grain size)−1/2 plot for MgAl2O4 was generated.