Plastic response by dislocation glide in solid helium under dc strain rate loading

TL;DR

This paper presents a theoretical model for dislocation glide and plasticity in solid helium-4, analyzing how temperature, strain rate, and dislocation density influence its mechanical response and related elastic anomalies.

Contribution

It introduces a comprehensive model incorporating dislocation dynamics and thermally activated processes specific to solid helium-4, predicting stress-strain behavior under various conditions.

Findings

Predicted stress-strain curves including yield point and work-hardening rate.

Identified how temperature and strain rate affect plastic deformation.

Provided testable predictions for experimental validation.

Abstract

We develop a model for the gliding of dislocations and plasticity in solid He-4. This model takes into account the Peierls barrier, multiplication and interaction of dislocations, as well as classical thermally and mechanically activated processes leading to dislocation glide. We specifically examine the dc stress-strain curve and how it is affected by temperature, strain rate, and dislocation density. As a function of temperature and shear strain, we observe plastic deformation and discuss how this may be related to the experimental observation of elastic anomalies in solid hcp He-4 that have been discussed in connection with the possibility of supersolidity or giant plasticity. Our theory gives several predictions for the dc stress strain curves, for example, the yield point and the change in the work-hardening rate and plastic dissipation peak, that can be compared directly to constant strain rate experiments and thus provide bounds on model parameters.