Elevated temperature aging of stress annealed Fe-Ga transduction alloys with built-in uniaxial stress anisotropies

M. Wun-Fogle; J. B. Restorff; A. E. Clark; Eric Summers

doi:10.1117/12.599881

16 May 2005 Elevated temperature aging of stress annealed Fe-Ga transduction alloys with built-in uniaxial stress anisotropies

M. Wun-Fogle, J. B. Restorff, A. E. Clark, Eric Summers

Author Affiliations +

Proceedings Volume 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics; (2005) https://doi.org/10.1117/12.599881
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2005, San Diego, California, United States

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 Fe_81.6Ga_18.4 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.

Citation Download Citation

M. Wun-Fogle, J. B. Restorff, A. E. Clark, and Eric Summers "Elevated temperature aging of stress annealed Fe-Ga transduction alloys with built-in uniaxial stress anisotropies", Proc. SPIE 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, (16 May 2005); https://doi.org/10.1117/12.599881

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