Low Temperature Plasticity of Molybdenum Single Crystals of High Purity

Abstract

Molybdenum single crystals of high purity of different orientations have been deformed by compression and tension in the temperature range 0.5 − 300 K with strain rates between 10–3 and 10–5 s–1. Plasticity decreases with decreasing temperature and is observed even at the temperature less than 1 K with more than 1 %. At compression (and sometimes at tension) a jump-like deformation caused by the kink formation process is observed at strain rates from 10–3 to 10–4 s–1. Stress drops are accompanied by great sound and thermal emission and amount to 900 MPa. In the whole temperature range studied the effect of the mode of deformation is not observed in the critical resolved shear stress. It strongly increases with decreasing temperature. The temperature dependence of the crss shows clearly the existence of three distinguished temperature ranges. They are discussed in terms of dislocation motion in the Peierls relief (Petukhov-Pokrovsky's and Seeger's theory).