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

Molecular dynamics simulation was employed to study the tensile behavior of single crystal titanium nanowires(NWs)with1120,1100and0001]orientations at different strain rates from 10~8s~(-1)to10~(11)s~(-1).When strain rates are above 10~(10)s~(-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 10~(10)s~(-1),deformation mechanisms of Ti NWs show strong dependence on orientation.For1120orientated NW,1011compression 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 along1120orientation is insensitive to strain rate.For 1100orientated NW,prismaticaslip is the main deformation mode at 10~8s~(-1).As the strain rate increases,more types of dislocations are activated during plastic deformation process.For0001]orientated NW,1012extension twinning is the main deformation mechanism,inducing the yield stress of0001]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.