Abstract

Deformation mechanisms in bcc metals, especially in dynamic regimes, show unusual complexity, which complicates their use in high-reliability applications. Here, we employ novel, high-velocity cylinder impact experiments to explore plastic anisotropy in single crystal specimens under high-rate loading. The bcc tantalum single crystals exhibit unusually high deformation localization and strong plastic anisotropy when compared to polycrystalline samples. Several impact orientations - [100], [110], [111] and [\[\bar{1}49\]] - are characterized over a range of impact velocities to examine orientation-dependent mechanical behavior versus strain rate. Moreover, the anisotropy and localized plastic strain seen in the recovered cylinders exhibit strong axial symmetries which differed according to lattice orientation. Two-, three-, and four-fold symmetries are observed. We propose a simple crystallographic argument, based on the Schmid law, to understand the observed symmetries. These tests are the first to explore the role of single-crystal orientation in Taylor impact tests and they clearly demonstrate the importance of crystallography in high strain rate and temperature deformation regimes. These results provide critical data to allow dramatically improved high-rate crystal plasticity models and will spur renewed interest in the role of crystallography to deformation in dynamics regimes.

Details

Title
Anisotropy and Strain Localization in Dynamic Impact Experiments of Tantalum Single Crystals
Author
Lim, Hojun 1 ; Carroll, Jay D 2 ; Battaile, Corbett C 1 ; Shuh Rong Chen 3 ; Moore, Alexander P 1 ; Lane, J Matthew D 1 

 Department of Computational Materials and Data Science, Sandia National Laboratories, Albuquerque, New Mexico, USA 
 Department of Materials Mechanics and Tribology, Sandia National Laboratories, Albuquerque, New Mexico, USA 
 Los Alamos National Laboratory, Los Alamos, New Mexico, USA 
Pages
1-6
Publication year
2018
Publication date
Apr 2018
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2021298201
Copyright
© 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.