Deformation twinning in pure aluminum under ultrahigh strain rate: Dependence of strain rate and crystallographic orientation

Abstract

Deformation twinning rarely occurs in single or polycrystalline aluminum due to its high stacking fault energy (SFE), even when deformed at low temperatures and/or high strain rate. Here we report electron back-scattered diffraction observations that provide evidence of deformation twinning in single crystal pure aluminum under shock loading. In addition, deformation twinning prefers to occur as twinning plane roughly paralleled to shear direction. Under shock loading, dislocation motion becomes jagged or even stopped, resulting in self-pinning. Then deformation twinning takes over as the dominant deformation mode. Our results provide a comprehensive understanding of the dynamic transition from dislocation slip to deformation twinning in pure aluminum under shock loading.