Deforming nanocrystalline nickel at ultrahigh strain rates

TitleDeforming nanocrystalline nickel at ultrahigh strain rates
Publication TypeJournal Article
Year of Publication2006
AuthorsWang, YM, Bringa, EM, McNaney, JM, Victoria, M, Caro, A, Hodge, AM, Smith, R, Torralva, B, Remington, BA, Schuh, CA, Jamarkani, H, Meyers, MA
JournalApplied Physics Letters
Date Published2006/02/06/

The deformation mechanism of nanocrystalline Ni (with grain sizes in the range of 30-100 nm) at ultrahigh strain rates (> 10(7) s(-1)) was investigated. A laser-driven compression process was applied to achieve high pressures (20-70 GPa) on nanosecond timescales and thus induce high-strain-rate deformation in the nanocrystalline Ni. Postmortem transmission electron microscopy examinations revealed that the nanocrystalline structures survive the shock deformation, and that dislocation activity is a prevalent deformation mechanism for the grain sizes studied. No deformation twinning was observed even at stresses more than twice the threshold for twin formation in micron-sized polycrystals. These results agree qualitatively with molecular dynamics simulations and suggest that twinning is a difficult event in nanocrystalline Ni under shock-loading conditions. (c) 2006 American Institute of Physics.