Anisotropy in room temperature microhardness and indentation fracture of xenotime

Microhardness and fracture anisotropy of natural single crystal xenotime were studied using Vickers and Knoop indentations. Indentations with loads from 10 to 500 g were applied on (0 0 1) and (1 0 0) crystallographic planes with various orientations of the indenter diagonal around the plane normal. The indentations were characterized with optical microscopy and SEM for cleavage, the anisotropy of microhardness, and indentation fracture toughness. Crack geometry was studied using FIB. The observations are interpreted using the crystallographic structure of xenotime.