The rare-earth-free body-centered-cubic FeGa-based alloys have an attractive combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost for use in sensor and actuator devices. This paper examines the influence of partially substituting Ga in FeGa alloys with Be and Al on their magnetostrictive behavior. Magnetic and magnetostrictive properties of the various ternary FeGaAl and FeGaBe alloys prepared by directional growth process are presented. It is shown that substitution of Ga with Al and Be can be made in FeGa alloys in certain composition ranges without a significant reduction in magnetostriction. Minimal reductions in magnetostriction when Ga is partially substituted by smaller Be or larger Al atoms in certain composition ranges indicate that local electronic environments are more important and that the effects of Ga and Be are additive.
Fe-Ga alloys, with composition around 27.5 at. % Ga, can be heat treated to obtain ␣ ͑A2, bcc͒, ␣Љ ͑D0 3 -like, ordered bcc͒, -Fe 3 Ga ͑D0 19 , ordered hexagonal͒, and ␣-Fe 3 Ga ͑L1 2 ordered fcc͒ phases. In this work, the influence of ␣Љ ordering on the magnetostriction coefficient ͑3/2͒ 100 , elastic constants ͑C 11 , C 12 , and C 44 ͒, and the magnetomechanical coefficients ͑B 1 ͒ of the single crystals of ␣-Fe-27.5 at.% Ga and ␣Љ-Fe-27.5 at. % Ga alloy is examined. Single crystals of Fe-27.5 at. % Ga were grown using the vertical Bridgman technique. Magnetostriction measurements were performed using ͓100͔-oriented single crystals. Elastic constants were estimated using resonant ultrasound spectroscopy and analysis technique. It is shown that the ␣Љ ordering in Fe-27.5 at. % Ga alloy decreases the ͑3/2͒ 100 value from that of ␣ phase. This is consistent with our previous work on polycrystalline at. % Ga alloys. The ␣-Fe-27.5 at.% Ga alloy single crystal was found to have a higher magnetoelastic coupling constant than the ␣Љ-Fe-27.5 at. % Ga alloy single crystal.
Articles you may be interested inInfluence of plastic deformation on the magnetostrictive behavior of [126]-oriented Fe-Ga alloy single crystals J. Appl. Phys. 111, 043911 (2012); 10.1063/1.3686680 Development of 〈100〉 crystallographic texture in magnetostrictive Fe-Ga microwires produced by in-rotating water spinning methodThe magnetostrictive behaviors of Fe-Ga, Fe-Mo, Fe-W, and other Fe alloys have been observed to be sensitive to their thermal history. In this work, the changes in the structure with thermal history and how they correlate with the observed magnetostriction values in Fe-Ga, Fe-W, and Fe-Mo single crystals are examined. Single crystals were grown using the vertical Bridgman crystal growth technique. The magnetostriction constant ͑3 / 2͒ 100 measured in ͑i͒ as-grown and air-cooled ͑DG͒ and ͑ii͒ annealed and water quenched single crystal samples of Fe-Ga and Fe-W alloys clearly indicate that annealing in the ␣-phase region followed by rapid quenching improves the magnetostriction values. High-resolution x-ray diffraction ͑XRD͒ studies on ͓100͔-oriented Fe-Ga as well as other Fe alloy single crystals show ͑i͒ a diffuse scattering peak indicative of short range ordering, the extent of which depends on composition and thermal history, and ͑ii͒ ͑200͒ peak splitting and broadening indicative of the presence of long range ordered coherent second phases and associated coherency strains. A detailed examination of the XRD patterns suggests that the changes in magnetostriction with composition and thermal history are related to the local strain modulations associated with the solutes, short range order, long range ordered coherent second phases, incoherent precipitates, and other structural defects.
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