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Cobalt-base ferromagnetic shape memory alloys
Ames Laboratory Conference Papers, Posters, and Presentations
  • Corneliu M. Craciunescu, University of Maryland - College Park
  • Yoichi Kishi, University of Maryland, College Park
  • Marc De Graef, Carnegie Mellon University
  • Thomas A. Lograsso, Iowa State University
Document Type
Conference Proceeding
Smart Structures and Materials 2002: Active Materials: Behavior and Mechanics
Publication Date
(32.7153292, -117.15725509999999)
Single crystalline and polycrystalline CoxNiyGa100-(x+y), 41 < xCo< 62 and 19.3 < yNi < 32.7, Ferromagnetic Shape Memory Alloys have been produced in the range of the Heusler-type composition. Elasto-mechanical properties have been analyzed for the annealed and quenched states, respectively. The mechanical spectroscopy data show the occurrence of martensitic phase transformation with the transition range and characteristics depending on the state and the composition of the alloys. For XCo approximately equals 49 +/- 1 at percent, the Ni/Ga ratio was shown to be in direct relationship with the transition temperature range, from an Ms of -100 degrees C for Ni/Ga approximately equals (21/29) to a +150 degrees C for a Ni/Ga ratio of about (26/25). For Ga approximately equals 27 +/- 0.4 at percent, the Co/Ni ratio is in indirect relationship with the transition temperature, with an Ms of -125 degrees C for a (53/19) ratio to a +175 degrees C for a ratio of about (49/26). Optical and electron microscopy shows that a typical thermoelastic martensitic transformation occurs. The L21 Structurbericht parent phase transforms into monoclinic or orthohombic martensitic upon cooling. The formation of a Co-rich phase has been observed for alloys with lower Ga content and is considered to be one of the reasons for the difference in the transformation range for annealed and quenched alloys.

Proc. SPIE 4699, Smart Structures and Materials 2002: Active Materials: Behavior and Mechanics, 235 (July 15, 2002); doi:10.1117/12.474980

Copyright 2002 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

Copyright Owner
Society of Photo Optical Instrumentation Engineers
Citation Information
Corneliu M. Craciunescu, Yoichi Kishi, Marc De Graef and Thomas A. Lograsso. "Cobalt-base ferromagnetic shape memory alloys" San Diego, CA(2002)
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