Anisotropy of microhardness on the (001) plane of ionic crystals such as NaCl

The anisotropy of microhardness,H, was investigated for the series of KCl-NaCl-NaF-LiF-MgO crystals using a Vickers indentor. The anisotropy had a similar character for deformation temperatures of 77, 293 and 800 K (H _100] >H _110]; however, the main factors affecting it were different for low and high temperatures. The dependence of the anisotropy coefficientK = (H =_100] –H _110] on the crystal hardness was found and it was shown that this dependence was significantly influenced by the deformation temperature. The results obtained support the dislocation mechanism of indentation formation on the crystals investigated.