Influence of an electric field on the plastic deformation of polycrystalline NaCl at elevated temperatures

The effect of a d.c, electric field of 1 kV/cm on the plastic deformation of polycrystalline 99.9% NaCl was determined in compression at 23-532 degrees C (0.28-0.75 T-M) and strain rate (epsilon) over dot = 8.3 x 10(-4) s(-1). Upon removing the effect of Joule heating it was found that the reduction in the how stress produced by the field increased with temperature from 0.28 to 0.4 T-M, reached a maximum at 0.4 T-M and then decreased, becoming nil at 0.75 T-M. It is proposed that the reduction in flow stress resulted from an enhancement of cross-slip due to an increase in stacking fault energy. The field had no detectable effect on the plastic deformation kinetics at constant structure in the temperature rang 0.28-0.6 T-M (cutting of forest dislocations), nor did it appear to have a significant influence on dislocation glide and climb at 0.75 T-M. (C) 1998 Acta Metallurgica Inc.