Orientation and strain rate dependent tensile behavior of single crystal titanium nanowires by molecular dynamics simulations

Abstract

Molecular dynamics simulation was employed to study the tensile behavior of single crystal titanium nanowires (NWs) with [112¯0], [1¯100] and [0001] orientations at different strain rates from 108s−1 to 1011s−1. When strain rates are above 1010s−1, the state transformation from HCP structure to amorphous state leads to super plasticity of Ti NWs, which is similar to FCC NWs. When strain rates are below 1010s−1, deformation mechanisms of Ti NWs show strong dependence on orientation. For [112¯0] orientated NW, {101¯1} compression twins (CTs) and the frequently activated transformation between CTs and deformation faults lead to higher plasticity than the other two orientated NWs. Besides, tensile deformation process along [112¯0] orientation is insensitive to strain rate. For [1¯100] orientated NW, prismatic <a> slip is the main deformation mode at 108s−1. As the strain rate increases, more types of dislocations are activated during plastic deformation process. For [0001] orientated NW, {101¯2} extension twinning is the main deformation mechanism, inducing the yield stress of [0001] orientated NW, which has the highest strain rate sensitivity. The number of initial nucleated twins increases while the saturation twin volume fraction decreases nonlinearly with increasing strain rate.