Grain boundary and triple junction constraints during martensitic transformation in shape memory alloys
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Ueland_Schuh_JAP_2013.pdf
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6.46 MB
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Author(s)
Ueland, Stian Melhus
Schuh, Christopher A.
Date Issued
August 2013
Journal
Journal of Applied Physics
Publisher
American Institute of Physics (AIP)
Citation
Ueland, Stian M., and Christopher A. Schuh. “Grain Boundary and Triple Junction Constraints During Martensitic Transformation in Shape Memory Alloys.” Journal of Applied Physics 114, no. 5 (2013): 053503. © 2013 AIP.
Version
Final published version
Abstract
We investigate the role of grain constraint upon martensitic transformation through in situ scanning electron microscope tensile experiments on shape memory microwires with a small number of grains and grain junctions. The martensite transformation morphology becomes more complex with increasing grain constraint: In unconstrained monocrystalline regions, the transformation is simple, single variant, and complete; near grain boundaries, the transformation is only partial, containing regions of untransformed austenite; near a triple junction, the morphology is complex, the transformation is partial and also multi-variant. These observations speak of transformation-induced stress concentrations that are more severe around triple junctions than around grain boundaries. Finite element modeling also provides an estimate for constraint effects on martensitic transformation yielding higher stresses near triple junctions than near grain boundaries. Towards the goal of developing polycrystalline Cu-based shape memory alloys that avoid intergranular fracture, our results support three design objectives: (1) Removal of triple junctions, (2) reduction of the total grain boundary area, and (3) geometry design containing unconstrained regions where the transformation can be most easily accommodated.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1063/1.4817170
