Partial-mediated slips in nanocrystalline Ni at high strain rate

Abstract

Previous experiments on nanocrystallineNi were conducted under quasistatic strain rates ( ∼ 3 × 10 − 3 ∕ s ) , which are much lower than that used in typical molecular dynamics simulations ( > 3 × 10 7 ∕ s ) , thus making direct comparison of modeling and experiments very difficult. In this study, the split Hopkinson bar tests revealed that nanocrystallineNi prefers twinning to extended partials, especially under higher strain rates ( 10 3 ∕ s ) . These observations contradict some reported molecular dynamics simulation results, where only extended partials, but no twins, were observed. The accuracy of the generalized planar fault energies is only partially responsible, but cannot fully account for such a difference.