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Proceedings Paper

Elevated temperature aging of stress annealed Fe-Ga transduction alloys with built-in uniaxial stress anisotropies
Author(s): M. Wun-Fogle; J. B. Restorff; A. E. Clark; Eric Summers
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Paper Abstract

The addition of Ga to b.c.c. Fe greatly increases the magnetostriction of Fe in the <100> directions (by a factor of 12 in Fe81Ga19). These Fe-based materials are mechanically tough and thus can be used under both compressive and tensile loading. The object of this study is to examine the effects of temperature aging on Fe81.6Ga18.4 alloys with built-in uniaxial stress anisotropies. To accomplish this, a transverse anisotropy was built into these positive magnetostrictive Fe-Ga (Galfenol) alloys by heat treatment under high compressive stresses. Annealing temperatures between 600 and 635°C and compressive stresses between 100 and 219 MPa produced uniaxial anisotropies between 2 and 9 kJ/m3. It is now possible to obtain magnetostrictions greater than 250 ppm over a broad range of stresses, extending from far into the compressive stress region through zero stress and into the tensile region. In this paper we examine the effect of aging at elevated temperatures on the built-in uniaxial anisotropy and magnetostriction of these alloys. Aging at 150°C for 697 hours left the magnetostriction unchanged. At 200°C most of the uniaxial anisotropy had disappeared after 525 hours. At 250°C, about two-thirds of the uniaxial stress was lost after 168 hours and very little remained after 336 hours.

Paper Details

Date Published: 16 May 2005
PDF: 8 pages
Proc. SPIE 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, (16 May 2005); doi: 10.1117/12.599881
Show Author Affiliations
M. Wun-Fogle, Naval Surface Warfare Ctr. (United States)
J. B. Restorff, Naval Surface Warfare Ctr. (United States)
A. E. Clark, Clark Associates, Inc. (United States)
Eric Summers, ETREMA Products, Inc. (United States)

Published in SPIE Proceedings Vol. 5761:
Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics
William D. Armstrong, Editor(s)

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