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Proceedings Paper

Magnetic and mechanical properties of FeNiCoTi and NiMnGa magnetic shape memory alloys
Author(s): Steven J. Murray; Ryoji Hayashi; Miguel A. Marioni; Samuel M. Allen; Robert C. O'Handley
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Paper Abstract

Large magnetic field induced strain shave been reported in ferromagnetic shape memory alloys. two such alloys, Ni-Mn-Ga and Fe-Ni-Co-Ti are explored. A single crystal of Ni-Mn-Ga is shown to deformed by bending approximately six degrees under the influence of an applied field. This deformation is caused by the motion of a single twin boundary with stable variants of martensite on either side. This effect was demonstrated using either divergent or homogeneous field. Fe-Ni-Co-Ti is a shape memory steel with high saturation magnetization being developed as a magnetic shape memory material. Material properties in this alloy can be controlled by composition and heat treatment and the effects of both are explored. Variation of the Ni to Co ratio has been found to have a strong effect on the martensite transition temperatures. Aging treatments cause Ni3Ti3 precipitates to form, which affect the martensite transition and subsequently the magnetization. The structure of most of the Fe-Ni-Co-Ti alloys tested showed lenticular martensite at room temperature with a single sample showing retained thin plate martensite in austenite after cooling to 77K.

Paper Details

Date Published: 12 July 1999
PDF: 8 pages
Proc. SPIE 3675, Smart Structures and Materials 1999: Smart Materials Technologies, (12 July 1999); doi: 10.1117/12.352794
Show Author Affiliations
Steven J. Murray, Massachusetts Institute of Technology (United States)
Ryoji Hayashi, Sanyo Steel (United States)
Miguel A. Marioni, Massachusetts Institute of Technology (United States)
Samuel M. Allen, Massachusetts Institute of Technology (United States)
Robert C. O'Handley, Massachusetts Institute of Technology (United States)


Published in SPIE Proceedings Vol. 3675:
Smart Structures and Materials 1999: Smart Materials Technologies
Manfred R. Wuttig, Editor(s)

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