The effect of electric fields (up to 0.1MV/m) upon the flow and fracture of cast polycrystalline samples was determined by compression at room temperature. In the absence of an electric field, the main slip system was found to be {110}<110>; with impurity-cation-vacancy dipoles constituting short-range obstacles to dislocation motion. The initial strain hardening rate was similar to that for stage-II in single crystals. Its decrease with strain was attributed to cross-slip. Plastic flow preceded fracture, which was intergranular in the absence of an electric field. The yield stress, flow stress, fracture stress and strain-hardening coefficient decreased with increasing electric field. A decrease of about 50% occurred at 0.1MV/m. This field was 1 to 2 orders of magnitude lower than that previously found to produce significant effects in NaCl single crystals. The fracture mode in the presence of the field was mixed (cleavage and intergranular). It was suggested that the main effect of the field was to increase cross-slip. This reduced the strain-hardening rate and thereby the flow and fracture stresses.

Effect of an Electric Field on the Plastic Deformation and Fracture of Polycrystalline NaCl. D.Yang, H.Conrad: Materials Science and Engineering A, 1997, 225[1-2], 173-83