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Title: Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates

Abstract

Deformation mechanisms of single-crystal Ta oriented at four different crystal orientations: [001], [011], [$$\bar{1}11]$$, [$$\bar{1}23]$$ and shock-compressed at two different peak pressures: 50 GPa and 65 GPa using a gas gun flyer-plate impact method have been studied. The main objective of this investigation is to elucidate the shock-induced shear transformations: deformation twinning and the α (bcc) → ω (pseudo-hexagonal) transition which were observed to take place in shock-deformed polycrystalline Ta at 30 GPa when the formation of low-energy cellular dislocation structure and polygonization due to dynamic recovery becomes suppressed. Emphasis is placed on the effects of crystal orientation and strain rate on the shock-induced dynamic recovery and shear transformations. Novel mechanisms for the formation of cellular dislocation structure and polygonization based on the coupling reactions of the 1/2 < $$\bar{1}11$$ > coplanar dislocations in the { $$\bar{1}11$$ } slip planes are proposed to elucidate the competition between dynamic recovery and shear transformations.

Authors:
 [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1481058
Report Number(s):
LLNL-TR-760731
949304
DOE Contract Number:  
AC52-07NA27344
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Hsiung, Luke L. Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates. United States: N. p., 2018. Web. doi:10.2172/1481058.
Hsiung, Luke L. Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates. United States. doi:10.2172/1481058.
Hsiung, Luke L. Tue . "Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates". United States. doi:10.2172/1481058. https://www.osti.gov/servlets/purl/1481058.
@article{osti_1481058,
title = {Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates},
author = {Hsiung, Luke L.},
abstractNote = {Deformation mechanisms of single-crystal Ta oriented at four different crystal orientations: [001], [011], [$\bar{1}11]$, [$\bar{1}23]$ and shock-compressed at two different peak pressures: 50 GPa and 65 GPa using a gas gun flyer-plate impact method have been studied. The main objective of this investigation is to elucidate the shock-induced shear transformations: deformation twinning and the α (bcc) → ω (pseudo-hexagonal) transition which were observed to take place in shock-deformed polycrystalline Ta at 30 GPa when the formation of low-energy cellular dislocation structure and polygonization due to dynamic recovery becomes suppressed. Emphasis is placed on the effects of crystal orientation and strain rate on the shock-induced dynamic recovery and shear transformations. Novel mechanisms for the formation of cellular dislocation structure and polygonization based on the coupling reactions of the 1/2 < $\bar{1}11$ > coplanar dislocations in the { $\bar{1}11$ } slip planes are proposed to elucidate the competition between dynamic recovery and shear transformations.},
doi = {10.2172/1481058},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {10}
}