Surface and subsurface Vickers indentation cracks in SiC, Si3N4, and sialon ceramics

The nature of subsurface cracks formed under and around Vickers hardness indentations is often assumed rather than identified. Subsurface cracks in four engineering ceramics are revealed using a penetrant technique, and flaw dimensions are recorded. The resulting data are used to investigate several aspects of indentation cracking, such as crack shape, functional relationships between indentation load and flaw dimensions, and the performance of indentation fracture toughness equations. An R curve is constructed for each of the materials. © 1995 The Institute of Materials.