Size effects in shape memory alloy microwires
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...
| Main Authors: | , |
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| Format: | Article |
| Language: | en_US |
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Elsevier
2016
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| Online Access: | http://hdl.handle.net/1721.1/102373 https://orcid.org/0000-0001-9856-2682 |
| _version_ | 1826213500200943616 |
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| author | Chen, Ying Schuh, Christopher A. |
| author2 | Massachusetts Institute of Technology. Department of Materials Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Materials Science and Engineering Chen, Ying Schuh, Christopher A. |
| author_sort | Chen, Ying |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T15:50:13Z |
| format | Article |
| id | mit-1721.1/102373 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:50:13Z |
| publishDate | 2016 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | mit-1721.1/1023732022-09-29T16:29:33Z Size effects in shape memory alloy microwires Chen, Ying Schuh, Christopher A. Massachusetts Institute of Technology. Department of Materials Science and Engineering Schuh, Christopher Chen, Ying Schuh, Christopher A. 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. Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies 2016-05-03T13:20:20Z 2016-05-03T13:20:20Z 2010-10 2010-09 Article http://purl.org/eprint/type/JournalArticle 13596454 1873-2453 http://hdl.handle.net/1721.1/102373 Chen, Ying, and Christopher A. Schuh. “Size Effects in Shape Memory Alloy Microwires.” Acta Materialia 59, no. 2 (January 2011): 537–553. https://orcid.org/0000-0001-9856-2682 en_US http://dx.doi.org/10.1016/j.actamat.2010.09.057 Acta Materialia Creative Commons Attribution-NonCommercial-NoDerivs License http://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf Elsevier Prof. Schuh via Angie Locknar |
| spellingShingle | Chen, Ying Schuh, Christopher A. Size effects in shape memory alloy microwires |
| title | Size effects in shape memory alloy microwires |
| title_full | Size effects in shape memory alloy microwires |
| title_fullStr | Size effects in shape memory alloy microwires |
| title_full_unstemmed | Size effects in shape memory alloy microwires |
| title_short | Size effects in shape memory alloy microwires |
| title_sort | size effects in shape memory alloy microwires |
| url | http://hdl.handle.net/1721.1/102373 https://orcid.org/0000-0001-9856-2682 |
| work_keys_str_mv | AT chenying sizeeffectsinshapememoryalloymicrowires AT schuhchristophera sizeeffectsinshapememoryalloymicrowires |