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Title: Plasticity and ultra-low stress induced twin boundary migration in nanotwinned Cu by in situ nanoindentation studies

Nanotwinned metals have rare combinations of mechanical strength and ductility. Previous studies have shown that detwinning occurs in plastically deformed nanotwinned metals. Although molecular dynamics simulations have predicted that fine nanotwins can migrate at low stress, there is little in situ evidence to validate such predictions. Also it is unclear if detwinning occurs prior to or succeeding plastic yielding. Here, by using in situ nanoindentation in a transmission electron microscope, we show that a non-elastic detwinning process in nanotwinned Cu occurred at ultra-low indentation stress (0.1 GPa), well before the stress necessary for plastic yielding. Furthermore, the in situ nanoindentation technique allows us to differentiate dislocation-nucleation dominated microscopic yielding preceding macroscopic yielding manifested by dislocation-transmission through twin boundaries. This study thus provides further insights for understanding plasticity in nanotwinned metals at microscopic levels.
Authors:
;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [3]
  1. Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States)
  2. Department of Electrical Engineering, Texas A and M University, College Station, Texas 77843 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22300000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COPPER; DISLOCATIONS; DUCTILITY; METALS; MIGRATION; MOLECULAR DYNAMICS METHOD; NUCLEATION; PLASTICITY; PRESSURE RANGE GIGA PA; SIMULATION; STRESSES; TRANSMISSION; TRANSMISSION ELECTRON MICROSCOPY