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Orientation-dependent plastic deformation mechanisms and competition with stress-induced phase transformation in microscale NiTi

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Abstract
Understanding the orientation-dependent deformation behavior of NiTi shape-memory alloys at small length scales is of importance for designing nano- and micro-electromechanical systems. However, a complete understanding of the orientation- and size-dependent competition between the various modes of slip, deformation twinning, and martensitic transformation in NiTi shape-memory alloys is still lacking, especially in micron-scale specimens. In the present study, we perform micro-compression tests on [001]- and [112]-oriented micro-pillars of a solutionized Ti-49.9at.% Ni alloy. Post-mortem TEM analysis of the deformed pillars reveal that the operating plastic deformation modes are {011}<100> slip and {114}<22 1 > deformation twinning, which compete with the martensitic transformation, depending on the crystal orientation. Furthermore, in both experiments and molecular dynamics simulations, we consistently find residual B19' martensite in a herringbone microstructure composed of finely spaced (001)(B19') compound twins instead of the generally assumed [011](B19') type II twins common in bulk samples, suggesting that the operative martensitic transformation mode may be size-dependent. Schmid factors in compression are calculated for all commonly reported slip, deformation twinning, and martensitic transformation modes as a function of crystallographic orientation, which rationalize the orientationdependent competition between these deformation modes. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Author(s)
고원석Christoph KirchlechnerDierk RaabeEdward L. PangHosun JunHyuk Jong BongPyuck-Pa ChoiWon Seok Choi
Issued Date
2021
Type
Article
Keyword
NiTiShape memory alloyPlastic deformationStress-induced martensitic transformationMicro-compression
DOI
10.1016/j.actamat.2021.116731
URI
https://oak.ulsan.ac.kr/handle/2021.oak/8962
https://ulsan-primo.hosted.exlibrisgroup.com/primo-explore/fulldisplay?docid=TN_cdi_gale_infotracacademiconefile_A656836603&amp;context=PC&amp;vid=ULSAN&amp;lang=ko_KR&amp;search_scope=default_scope&amp;adaptor=primo_central_multiple_fe&amp;tab=default_tab&amp;query=any,contains,Orientation-dependent%20plastic%20deformation%20mechanisms%20and%20competition%20with%20stress-induced%20phase%20transformation%20in%20microscale%20NiTi&amp;offset=0&amp;pcAvailability=true
Publisher
ACTA MATERIALIA
Location
영국
Language
영어
ISSN
1359-6454
Citation Volume
208
Citation Number
1
Citation Start Page
116731
Citation End Page
116731
Appears in Collections:
Engineering > Material Engineering
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