|Title||Deforming nanocrystalline nickel at ultrahigh strain rates|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Wang, YM, Bringa, EM, McNaney, JM, Victoria, M, Caro, A, Hodge, AM, Smith, R, Torralva, B, Remington, BA, Schuh, CA, Jamarkani, H, Meyers, MA|
|Journal||Applied Physics Letters|
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.