REGULARITIES OF MGO SINGLE-CRYSTAL FAILURE IN MICROINDENTATION

The peculiarities of the fracture of indentations on the (001) plane of MgO single crystals were investigated for two orientations of the Vickers indentor: (i) the indentation diagonals were parallel to the 〈100〉 direction, and (ii) the diagonals were parallel to 〈110〉. A brittleness anisotropy was revealed. A specific structure of "square" cracks was observed inside the indentations of the first orientation. Such a structure did not appear in the case of the second orientation. An explanation of the brittleness anisotropy was suggested using a model of material plastic flow in the indentation and considering the interaction of dislocations belonging to the active slip planes. © 1990 Chapman and Hall Ltd.