Plastic Deformation and Creep of Sodium Chloride Crystals at Liquid Helium Temperatures

The plastic deformation of single crystals of NaCl in uniaxial compression was studied between 1.5 and 4.2 °K and also at 77 °K. The flow stress increased rapidly with decreasing temperature, being about 2.3 kp mm−2 at 2 °K. Flow occurred by the widening of dislocation bands, and considerable amounts of transient creep were observed. Analysis of the creep constant, stress dependence of strain rate, and temperature dependence of flow stress lead to the conclusion that the deformation can be explained in terms of the thermally activated motion of dislocations.