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Persistent URL
http://purl.org/net/epubs/work/12309961
Record Status
Checked
Record Id
12309961
Title
Twinning anisotropy of tantalum during nano-indentation
Contributors
S Goel (Queen's Univ., Belfast)
,
B Beake (Micro Materials Ltd, Wrexham and dalton Research Institute, Manchester)
,
C-W Chan (Robert Gordon Univ.)
,
NH Faisal (Robert Gordon Univ.)
,
N Dunne (Queen's Univ., Belfast)
Abstract
Unlike other BCC metals, the plastic deformation of nanocrystalline Ta during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2<111> type and <100> type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of tantalum (Shear modulus/ 2?~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light to this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale
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STFC
,
HC
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Language
English (EN)
Type
Details
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Year
Journal Article
Mater Sci Eng A
627 (2015): 249-261.
http://dx.doi.org…6/j.msea.2014.12.075
2015
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