Twinning behavior and variant selection mechanism of b.c.c tantalum during dynamic plastic deformation

Abstract

In this paper, the microstructure and twinning behavior of tantalum (Ta) during dynamic plastic deformation (DPD) were jointly analyzed in combination with impact experiments and molecular dynamics simulations, with a focus on the mechanism of variant selection for twinning. The results indicated that twins nucleate at grain boundaries and gradually grows with increasing deformation until it penetrates the entire grain. Due to the difference of grain boundary dislocation density, strain rate and deformation temperature have significant impacts on the quantity and distribution of twins. In addition, at room temperature, nearly half of the twin variants in DPD samples do not conform to Schmid law, and almost all the twin variants in liquid nitrogen samples do not follow to Schmid law. The activation of these non-Schmid variants is mainly affected by the strain coordination. Through this study, we have deepened our understanding of the dynamic microstructural response of Ta under high-speed deformation conditions.