Direct Measurement of the Softening ofV3Si at Low Temperature

Abstract

The softening of ${\mathrm{V}}_3$Si at low temperatures has been measured by applying a static load and measuring the transverse strain as the specimen is cooled. The softening observed between 20 and 30°K is approximately the same as that calculated from Testardi et al.'s ultrasonic measurements. However, the strains for a given applied stress are significantly lower than those obtained from moduli calculated from ultrasonic measurements. Since the static measurements involve stresses two orders of magnitude greater than the ultrasonic measurements, a possible explanation of our results is that the elastic constants might have a large stress dependence and that a stiffening of the lattice sets in sharply at moderate strains.