204. LASER COMPRESSION OF NANOCRYSTALLINE TANTALUM

Department: NanoEngineering
Research Institute Affiliation: Graduate Program in Materials Science and Engineering
Faculty Advisor(s): Marc A. Meyers

Primary Student
Name: Chia-Hui Lu
Email: chl086@ucsd.edu
Phone: 858-366-3265
Grad Year: 2012

Abstract
Nanocrystlline tantalum was prepared by HPT (High Pressure Torsion) from monocrystalline [100] stock yielding a grain size of 70 nm. It was subjected to laser driven compression at energy levels of ~ 350 J to ~ 850 J in the Omega facility (LLE, U. of Rochester) yielding pressures as high as ~ 180 GPa. The laser beam created a crater of significant depth (~ 100Ám). Transmission electron microscopy (TEM) revealed dislocations in the grains but no twins in contrast with monocrystalline tantalum. Hardness measurements were conducted and show the same trend as single crystalline tantalum. The grain size was found to increase close to the energy deposition surface.

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