Impact behavior and constitutive model of nanocrystalline Ni under high strain rate loading |
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| Affiliation: | 1. Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14850, USA;2. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA;3. Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA;4. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA;1. Department of Materials Science and Engineering, Johns Hopkins University, 3400N. Charles Street, Baltimore, MD, United States;2. Department of Materials Science & Engineering, Drexel University, Philadelphia, PA, United States;3. Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, United States;4. American Society for Engineering Education, Washington, DC, United States;5. Material, Physical, and Chemical Sciences, Sandia National Laboratories, Albuquerque NM, United States;6. Department of Mechanical Engineering, Colorado School of Mines, Golden CO, United States |
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| Abstract: | To investigate mechanical properties and deformation mechanisms of nanocrystalline materials under high strain rate, dynamic impact tests for nanocrystalline Ni bulk prepared by high-energy ball milling combined with compaction and hot-pressure sintering were carried out under different high strain rates on Split Hopkinson bar. Compared with the testing results under quasi-static strain rate, the nanocrystalline Ni has higher strength under high strain rate. Meanwhile, the impact stress–strain curves exhibit rate-dependence strength and light strain hardening behavior. Subsequently, a mechanism of dislocation gliding in combination of grain boundary sliding was discussed and a constitutive model was built under high strain rate loading based on the mechanism. The predictions of the constitutive model under high strain rates show good agreements with the experimental data. Finally, the properties of the nanocrystalline Ni were discussed in detail. |
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