Latent hardening of doped alkali halide single crystals

Abstract

The latent hardening of various alkali halide single crystals is investigated as a function of prestrain and concentration of divalent impurity ions. With a suitable choice of the specimen dimensions it is possible to produce alternating slip on oblique slip systems in successive deformation steps. The latent hardening ratio (LHR) is found to be nearly constant in the measured strain range; it decreases with increasing doping. A correlation of LHR with stacking fault energy and ionic polarizability is observed. A forest dislocation model including as an essential parameter the ratio of primarily produced edge to screw dislocations is developed.

An electron microscope study of the origin of latent hardening in NaCl

“…The reason for this is that here the resulting flow stress increase covers a much larger range than for other materials. Latent hardening has been studied for several rock-salt-type ionic crystals by Alden (1963Alden ( , 1964, Kear, Silverstone and Pratt (1966), Davidge (1966), Nakada and Keh (1969), Zimikin, Samoilova andSmirnov (1970,1974), Steinbrech, Skrotzki and Haasen (1978) and Chaki and Li (1987). The results may be summarized as follows.…”