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Title: Role of local stresses on co-zone twin-twin junction formation in HCP magnesium

Abstract

Twin-twin interactions control the formation of twin-twin junctions (TTJ) in hexagonal metals when multiple twin variants are activated in a grain. In this work, we employ a combination of two computational techniques, a 3D full-field crystal plasticity model (CP) and large-scale molecular dynamics (MD), to study the TTJ formation associated with two non-parallel {101¯2} twins in Mg. The local intra-granular stresses generated by discrete twins are computed using a spatially resolved CP model. Atomic-scale knowledge regarding formation processes and local stresses is revealed by MD. The combined analyses suggest that the twin junction forms by the migration of the boundaries of both, the impinging and impinged twin, taking place in the immediate vicinity of the contact point. It is further shown that local stress fields that are generated after initial contact promote thickening of the impinging twin, and may facilitate nucleation of a new twin on the opposite boundary of the recipient twin. In conclusion, calculations of the strain energies suggest that formation of the co-zone twin-twin junction is energetically favorable but detwinning of the TTJ upon load reversal or under cyclic loading is not.

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Nebraska, Lincoln, NE (United States)
  3. Univ. of California, Santa Barbara, CA (United States)
  4. Univ. of Nebraska, Lincoln, NE (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1498053
Report Number(s):
LA-UR-18-29412
Journal ID: ISSN 1359-6454
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 168; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Twin-twin junction; Local stresses; Crystal plasticity; Molecular dynamics; Magnesium

Citation Formats

Kumar, Mariyappan Arul, Gong, Mingyu, Beyerlein, I. J., Wang, Jian, and Tomé, Carlos N.. Role of local stresses on co-zone twin-twin junction formation in HCP magnesium. United States: N. p., 2019. Web. doi:10.1016/j.actamat.2019.02.037.
Kumar, Mariyappan Arul, Gong, Mingyu, Beyerlein, I. J., Wang, Jian, & Tomé, Carlos N.. Role of local stresses on co-zone twin-twin junction formation in HCP magnesium. United States. doi:10.1016/j.actamat.2019.02.037.
Kumar, Mariyappan Arul, Gong, Mingyu, Beyerlein, I. J., Wang, Jian, and Tomé, Carlos N.. Tue . "Role of local stresses on co-zone twin-twin junction formation in HCP magnesium". United States. doi:10.1016/j.actamat.2019.02.037.
@article{osti_1498053,
title = {Role of local stresses on co-zone twin-twin junction formation in HCP magnesium},
author = {Kumar, Mariyappan Arul and Gong, Mingyu and Beyerlein, I. J. and Wang, Jian and Tomé, Carlos N.},
abstractNote = {Twin-twin interactions control the formation of twin-twin junctions (TTJ) in hexagonal metals when multiple twin variants are activated in a grain. In this work, we employ a combination of two computational techniques, a 3D full-field crystal plasticity model (CP) and large-scale molecular dynamics (MD), to study the TTJ formation associated with two non-parallel {101¯2} twins in Mg. The local intra-granular stresses generated by discrete twins are computed using a spatially resolved CP model. Atomic-scale knowledge regarding formation processes and local stresses is revealed by MD. The combined analyses suggest that the twin junction forms by the migration of the boundaries of both, the impinging and impinged twin, taking place in the immediate vicinity of the contact point. It is further shown that local stress fields that are generated after initial contact promote thickening of the impinging twin, and may facilitate nucleation of a new twin on the opposite boundary of the recipient twin. In conclusion, calculations of the strain energies suggest that formation of the co-zone twin-twin junction is energetically favorable but detwinning of the TTJ upon load reversal or under cyclic loading is not.},
doi = {10.1016/j.actamat.2019.02.037},
journal = {Acta Materialia},
number = C,
volume = 168,
place = {United States},
year = {2019},
month = {2}
}

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This content will become publicly available on February 26, 2020
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