Strain-rate effect on plasticity and co-phase transformation in single crystal titanium: A molecular dynamics study

摘要

We employ molecular dynamics simulations to investigate the role of applied strain rate on plasticity (twinning and dislocation slip) and omega-phase transformation in single crystal titanium for loading perpendicular to the c-axis under uniaxial strain conditions. We find a significant dependence of microstructural evolution on the applied strain rate. The applied loading leads to the activation of {10 (1) over bar2} twins and omega-phase transformation. For loading along 2(1)over bar(1) over bar0 direction, four twin variants activate while for loading along 01(1)over bar0 direction, only two twin variants activate. The twin number density decreases with a decrease in applied strain rate for both loading conditions. For the case where four twin variants activate, the overall reorientations at each applied strain rate are large in comparison to the case where only two twin variants activate. In addition to this, the overall reorientations decrease with a decrease in applied strain rate for both loading conditions. The omega-phase volume fraction decreases with a decrease in applied strain rate for both the cases of applied loading conditions. For the case where only two variants activate, the overall twin volume fraction is highest at each applied strain rate in comparison to the case where four twin variants activate. In addition to this, the overall twin volume fraction is lowest at highest applied strain rate while it is highest at lowest applied strain rate for both loading conditions. These observations should be useful to develop physics based dynamic material strength models for coupled evolution of plasticity and omega-phase transformation.