Effect of annealing under high pressures on dislocations in lithium fluoride, aluminum, copper and iron

Abstract

Single crystals of lithium fluoride, aluminum, copper and iron have been annealed for 1 hr at 500°–600°C under a pressure of 40 kb. The dislocation structure was studied, before and after treatment, by the Berg-Barrett X-ray technique in aluminum and by etch pitting in the other materials. The high-pressure anneals produced no detectable change in the dislocation densities of any of the four materials. For lithium fluoride a double-etch technique revealed that far less dislocation motion had occurred in the crystal annealed under pressure than in one given the same thermal treatment at atmospheric pressure. These results are consistent with calculations which show that the application of pressure will reduce both the climb and glide rates of a dislocation.