First In Situ Observation of Partial Dislocation-Mediated Plastic Flow in Shocked Single-Crystal Aluminum

In single-crystal aluminum (Al), partial dislocations are believed to play a crucial role in plasticity under extreme loading conditions; however, their activation has seldom been observed in experiments. In this work, dynamic dislocation activation of laser-shocked single-crystal Al is investigated by a combined effort of time-resolved x-ray diffraction (XRD) experiments and nonequilibrium molecular dynamics (MD) simulations. In situ XRD images of deformed single-crystal Al were captured during shock loading along the [100] and [110] orientations. MD simulations, along with calculations of slip-induced crystal plane rotation, were performed to interpret diffraction patterns. Our findings reveal that, along the [100] orientation, plastic flow is dominated by partial dislocations, whereas for the [110] orientation, flow involves both partial and full dislocations. This work thus offers unprecedented insights into the plastic mechanisms of single-crystal Al under high strain rate loading, which has never been observed in postmortem analysis or quasi-static loading.