Deformation of nanocrystalline materials at ultrahigh strain rates - microstructure perspective in nanocrystalline nickel
Nanocrystalline materials with grain sizes smaller than 100 nm have attracted extensive research in the past decade. Due to their high strength, these materials are good candidates for high pressure shock loading experiments. In this paper, we investigated the microstructural evolutions of nanocrystalline nickel with grain sizes of 10-50 nm, shock-loaded in a range of pressures (20-70 GPa). A laser-driven isentropic compression process was applied to achieve high shock-pressures in a timescale of nanoseconds and thus the high-strain-rate deformation of nanocrystalline nickel. Postmortem transmission electron microscopy (TEM) examinations reveal that the nanocrystalline structures survive the shock deformation and that dislocation activity is the prevalent deformation mechanism when the grain sizes are larger than 30 nm, without any twinning activity at twice the stress threshold for twin formation in micrometer-sized polycrystals. However, deformation twinning becomes an important deformation mode for 10-20 nm grain-sized samples.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 893573
- Report Number(s):
- UCRL-PROC-220628; TRN: US200625%%409
- Resource Relation:
- Journal Volume: 134; Conference: Presented at: 8th International Conference on Mechanical and Physical Behavior of Materials Under Dynamic Loading (Dymat 2006), Dijon, France, Sep 11 - Sep 15, 2006
- Country of Publication:
- United States
- Language:
- English
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