Hardening of Potassium Chloride Single Crystals by Quenching and Irradiation

Abstract

The effect of heat treatment and irradiation on the hardening properties of potassium chloride single crystals of varying impurity concentrations is investigated. Some specimens were quenched in cold acetone (0°C) from temperatures over the range of 100° to 650°C, and other samples were irradiated with cobalt 60 photons or with 1.5‐MeV electrons to doses of 1019 photons or about 3.8×1015 electrons, respectively. The quenching results are most easily explained in terms of the dissociation of vacancy‐impurity complexes for temperatures to 375°C. It was not possible at the quenching rate utilized, to quench thermal vacancies in the lattice. Also, even for quench temperatures below 375°C, there is evidence that some annealing out of the defects occurred. The irradiation results show that relatively impure samples have quite different hardening properties for a given dose of irradiation, electron or gamma, than do the purer specimens.