Crystal plasticity finite element simulation of lattice rotation and x-ray diffraction during laser shock-compression of Tantalum

TL;DR

This study uses crystal plasticity finite element modeling to analyze lattice rotation during laser shock compression of tantalum, linking plasticity kinetics to observed x-ray diffraction patterns and identifying a transition at 27 GPa.

Contribution

The paper introduces a finite element model that accurately predicts lattice rotations and deformation kinetics during shock compression, validated against experimental x-ray data.

Findings

Lattice rotation correlates with plasticity kinetics.

A transition at ~27 GPa separates slow and fast deformation regimes.

Model fits experimental x-ray diffraction data well.

Abstract

Wehrenberg et. al. [Nature 550 496 (2017)] used ultrafast in situ x-ray diffraction at the LCLS x-ray free-electron laser facility to measure large lattice rotations resulting from slip and deformation twinning in shock-compressed laser-driven [110] fibre textured tantalum polycrystal. We employ a crystal plasticity finite element method model, with slip kinetics based closely on the isotropic dislocation-based Livermore Multiscale Model [Barton et. al., J. Appl. Phys. 109 (2011)], to analyse this experiment. We elucidate the link between the degree of lattice rotation and the kinetics of plasticity, demonstrating that a transition occurs at shock pressures of $\sim$27 GPa, between a regime of relatively slow kinetics, resulting in a balanced pattern of slip system activation and therefore relatively small net lattice rotation, and a regime of fast kinetics, due to the onset of nucleation, resulting in a lop-sided pattern of deformation-system activation and therefore large net lattice rotations. We demonstrate a good fit between this model and experimental x-ray diffraction data of lattice rotation, and show that this data is constraining of deformation kinetics.