Transfer or blockage: Unraveling the interaction between deformation twinning and grain boundary in tantalum under shock loading with molecular dynamics

The interaction between {112}<111> deformation twinning and grain boundary in coaxial polycrystalline tantalum under shock compression was studied with molecular dynamics simulation under different grain pair misorientation angles (MA) and geometric compatibility factor (m’). Generally, in the coaxial polycrystal, the value of MA determines the occurrence of twin transfer (TT) or twin blockage (TB), i.e., twin transfer occurs at MA ≤ 29° with twin blockage otherwise. Under TT, the value of m’ affects the selection of twin variants., i.e., the twin system with a larger m’ is easier to active. The morphology of twin pairs is ruler-shaped and lenticular under TT and TB, respectively, with different thickening mechanisms, including grain boundary dislocation emission.