Nanoengineering Applied to Tungsten

Report No. ARL-RP-123
Authors: Q. Wei, B. E. Schuster, L. J. Kecskes, R. J. Dowding, K. C. Cho, L. S. Magness, E. Ma, K. T. Ramesh, and R. Z. Valiev
Date/Pages: May 2006; 16 pages
Abstract: We have investigated the microstructure and mechanical properties of fully dense tungsten with ultrafine-grained (UFG) and nanocrystalline (NC) microstructure. The UFG/NC tungsten was processed by severe plastic deformation at low homologous temperatures (T/Tm). To obtain the UFG microstructure, a combination of equal channel angular pressing at relatively high temperatures followed by rolling at lower temperatures was employed, which resulted in an average grain size of ~500 nm. To obtain the nanocrystalline microstructure (grain size ~100 nm and below), high-pressure torsion was utilized. Our experimental results show that the UFG/NC microstructures not only significantly elevate the strength of tungsten, they also re-instate its ductility, decrease its strain rate sensitivity, and reduce its work hardening capability. These factors work together to greatly enhance the susceptibility of tungsten to adiabatic localization under uni-axial dynamic loading.
Distribution: Approved for public release
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Last Update / Reviewed: May 1, 2006