Determination of post-yield hardening response in a ZrB2 ceramic

The extent of dislocation-based plasticity in ceramics is limited and often accompanied by microcracking. This limitation has precluded the investigation of post-yield plastic response in ceramics. Using low-load nanoindentations and by tracking the hardness of selected grains before and after plastic deformation, the influence of microcracking and variability in microhardness due to grain orientation were minimized and the post-yield response of polycrystalline ZrB2 ceramic was determined. The observed increase in nanoindentation hardness after plastically deforming isolated ZrB2 grains indicates conclusively the existence of post-yield strain hardening.