Deformation and dislocation evolution in body-centered-cubic single- and polycrystal tantalum

TL;DR

This paper introduces a continuum crystal plasticity model for bcc tantalum that captures deformation mechanisms, dislocation evolution, and microstructural changes across various strain rates, temperatures, and crystal structures, validated by experiments and simulations.

Contribution

The study presents a unified modeling framework informed by dislocation dynamics that accurately predicts tantalum's deformation and microstructural evolution at multiple scales and conditions.

Findings

Model captures large inelastic behavior of tantalum across strain rates and temperatures.

Dislocation interactions influence slip activity and strain-hardening.

Experimental data supports model predictions of texture and dislocation density evolution.

Abstract

A physically-informed continuum crystal plasticity model is presented to elucidate the deformation mechanisms and dislocation evolution in body-centered-cubic (bcc) tantalum widely used as a key structural material for mechanical and thermal extremes. We show our unified structural modeling framework informed by mesoscopic dislocation dynamics simulations is capable of capturing salient features of the large inelastic behavior of tantalum at quasi-static (10$^{-3}$ s$^{-1}$) to extreme strain rates (5000 s$^{-1}$) and at room temperature and higher (873K) at both single- and polycrystal levels. We also present predictive capabilities of our model for microstructural evolution in the material. To this end, we investigate the effects of dislocation interactions on slip activities, instability and strain-hardening behavior at the single crystal level. Furthermore, ex situ measurements on crystallographic texture evolution and dislocation density growth are carried out for the polycrystal tantalum specimens at increasing strains. Numerical simulation results also support that our modeling framework is capable of capturing the main features of the polycrystal behavior over a wide range of strains, strain rates and temperatures. The theoretical, experimental and numerical results at both single- and polycrystal levels provide critical insight into the underlying physical pictures for micro- and macroscopic responses and their relations in this important class of refractory bcc materials undergoing severe inelastic deformations.