Size effects in shape memory alloy microwires
Name
Schuh_Size effects.pdf
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1.71 MB
Format
Adobe PDF
Checksum (MD5)
c197d487aac6ae386078bea782891d98
Author(s)
Chen, Ying
Schuh, Christopher A.
Date Issued
October 2010
Journal
Acta Materialia
Publisher
Elsevier
Citation
Chen, Ying, and Christopher A. Schuh. “Size Effects in Shape Memory Alloy Microwires.” Acta Materialia 59, no. 2 (January 2011): 537–553.
Version
Author's final manuscript
Abstract
In shape memory alloys, the reversible phase transformations between austenite and martensite give rise to superelasticity and shape memory properties. Here we systematically study the sample size dependence of these properties and the associated transformations in polycrystalline shape memory alloy microwires with a bamboo grain structure, i.e. where the wire diameter is completely spanned by individual grains. Cu–Al–Ni wires with diameters ranging from ∼500 down to ∼20 μm are fabricated by the Taylor liquid processing technique, and are characterized by both isothermal uniaxial tensile testing and mechanically constrained thermal cycling. We observe size effects in both the transformation stresses and temperatures. What is more, we find that the stress hysteresis in a mechanical cycle and the temperature hysteresis in a thermal cycle both increase with decreasing wire diameter, particularly for wires smaller than 100 μm. A direct consequence of the increased hysteresis is enhanced energy dissipation (i.e. damping capacity) in smaller wires. We also discuss possible physical origins of the observed size effects, including interface and surface energies, stored elastic energy, heat transfer and internal friction.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1016/j.actamat.2010.09.057
