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Title: Grain size constraints on twin expansion in hexagonal close packed crystals

Deformation twins are stress-induced transformed domains of lamellar shape that form when polycrystalline hexagonal close packed metals, like Mg, are strained. Several studies have reported that the propensity of deformation twinning reduces as grain size decreases. Here, we use a 3D crystal plasticity based micromechanics model to calculate the effect of grain size on the driving forces responsible for expanding twin lamellae. The calculations reveal that constraints from the neighboring grain where the grain boundary and twin lamella meet induce a stress reversal in the twin lamella. A pronounced grain size effect arises as reductions in grain size cause these stress-reversal fields from twin/grain boundary junctions to affect twin growth. We further show that the severity of this neighboring grain constraint depends on the crystallographic orientation and plastic response of the neighboring grain. We show that these stress-reversal fields from twin/grain boundary junctions will affect twin growth, below a critical parent grain size. Finally, these results reveal an unconventional yet influential role that grain size and grain neighbors can play on deformation twinning.
Authors:
 [1] ;  [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-16-24576
Journal ID: ISSN 0021-8979; TRN: US1701355
Grant/Contract Number:
AC52-06NA25396; FWP 06SCPE401
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 15; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
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); USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1343711
Alternate Identifier(s):
OSTI ID: 1329441