Effect of Grain Size on Strength and Fracture Toughness in Alumina

Abstract

Three-point bending and fracture toughness tests of alumina specimens with various grain sizes were carried out to investigate the effects of grain size on bending strength and fracture toughness. The bending strength increased with decreasing grain size. The intrinsic fracture toughness, which can be obtained by the CSF method, is independent of grain size. On the other hand, the apparent fracture toughness with slow crack growth increased with increasing grain size due to the R-curve behavior, which was found for materials with coarse grains in the BI, FP and CN specimens.