The change of the load-microhardness curves of NaCl single crystals due to heat treatment and impurity

In order to determine the physical meaning of the constantsa andn in the equationH=1854·a·d n−2 describing the microhardness of the alkali halide crystals quenching experiments were carried out on NaCl: Ca systems. By means of combined electrical conductivity and microhardness measurements it was found that values of the constantsa andn depend on the concentration and state of impurities in the crystals. The results obtained show thata andn are not defined by the crystal type alone, but also by the type and concentration of impurity centres interacting with the dislocations.