Unraveling the temperature dependence of the yield strength in single-crystal tungsten using atomistically-informed crystal plasticity calculations

TL;DR

This study develops a physics-based crystal plasticity model for tungsten single crystals that accurately predicts temperature-dependent yield strength using atomistic data, capturing key dislocation behaviors without experimental fitting.

Contribution

The paper introduces a parameter-free, atomistically-informed crystal plasticity model that effectively predicts the temperature and strain-rate dependence of tungsten's yield strength across multiple orientations.

Findings

Model matches experimental yield stress data across temperatures.

Calculated yield surfaces for biaxial loading conditions.

Determined strain-rate sensitivity of tungsten crystals.

Abstract

We use a physically-based crystal plasticity model to predict the yield strength of body-centered cubic (bcc) tungsten single crystals subjected to uniaxial loading. Our model captures the thermally-activated character of screw dislocation motion and full non-Schmid effects, both of which are known to play a critical role in bcc plasticity. The model uses atomistic calculations as the sole source of constitutive information, with no parameter fitting of any kind to experimental data. Our results are in excellent agreement with experimental measurements of the yield stress as a function of temperature for a number of loading orientations. The validated methodology is then employed to calculate the temperature and strain-rate dependence of the yield strength for 231 crystallographic orientations within the standard stereographic triangle. We extract the strain-rate sensitivity of W crystals at different temperatures, and finish with the calculation of yield surfaces under biaxial loading conditions that can be used to define effective yield criteria for engineering design models.