Title
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Microstructure of surface and subsurface layers of a Ni-Ti shape memory microwire
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Author
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Abstract
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The microstructure of a 55 Êm diameter, cold-worked Ni-Ti microwire is investigated by different transmission electron microscopy techniques. The surface consists of a few hundred nanometer thick oxide layer composed of TiO and TiO2 with a small fraction of inhomogeneously distributed Ni. The interior of the wire has a core-shell structure with primarily B2 grains in the 1 Êm thick shell, and heavily twinned B19 martensite in the core. This core-shell structure can be explained by a concentration gradient of the alloying elements resulting in a structure separation due to the strong temperature dependence of the martensitic start temperature. Moreover, in between the B2 part of the metallic core-shell and the oxide layer, a Ni3Ti interfacial layer is detected. |
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Language
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English
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Source (journal)
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Microscopy and microanalysis. - Cambridge, Mass.
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Publication
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Cambridge, Mass.
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2009
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ISSN
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1431-9276
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DOI
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10.1017/S1431927609090059
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Volume/pages
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15
(2009)
, p. 62-70
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ISI
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000262912700009
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Full text (Publisher's DOI)
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Full text (open access)
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