Microhardness and defectiveness of solid-solution crystals of alkali halide compounds of the system KCl-KBr

Abstract

A study has been made of the dependence of microhardness (H), dislocation. density (N), vacancy-Schottky defect-density (χ_v), and length of the rays of etch-figure stars (L) on the composition of solidsolution crystals of the system KCl-KBr.

The dependence of N on the composition of the crystals is represented by a curve with two maxima related to solid solutions with small additions of KCl and KBr. The curves of the composition dependence of H, L, χ_v, and melting point are asymmetrical; crystals with a smaller content of KCl in KBr correspond to a larger vacancy density χ_v, larger deviations from additivity of microhardness, and lower values of L and the melting point. With decrease of the bond forces in the crystal lattice of the solid solutions and with increase in the vacancy content, there is a reduction in the distance traversed by the leading dislocation under the action of a concentrated load on the crystal, a reduction in the length of the rays of the etch-figure stars, and an increase in microhardness.