Deformation behavior and magnetostriction of polycrystalline Fe-Ga-X (X=B,C,Mn,Mo,Nb,NbC) alloys

Single crystal samples of quenched Fe81.3Ga18.7 and of slow cooled Fe81.3Ga18.6C0.08 exhibit magnetostriction of similar to 400 ppm. However, they also exhibit a sufficiently high permeability that eddy currents, which form in proportion to sample thickness, limit their operation at high frequencies. During attempts to roll thin sheets of Fe81.3Ga18.7 and carbon-added Fe81Ga19 alloys, cracks formed along grain boundaries and subsequently samples fractured during hot rolling such that the alloy was too brittle to make thin sheets. In this paper, the influence of alloying additions of B, Mn, Mo, Nb, and NbC on the deformation behavior and magnetostriction of Fe-Ga alloy was investigated. These alloying additions except Mn improved the roll ability and provided a high quality finished rolled sheets with thickness ranging from 0.18 to 0.35 mm. Results are shown to demonstrate that the fracture mode of 1.0% Mo- or 0.5% B-added Fe81Ga19 alloy was changed from an intergranular to a transgranular fracture mode with cleavage. Annealed sheets with additions of 0.5% B, 1.0% B, 0.5% Mo, 2.0% Mo, 0.5% Nb, and 1.0% NbC exhibited the maximum magnetostrictions of 103, 160, 127, 88, 121, and 183 ppm, respectively. Electron backscattering diffraction (EBSD) analysis showed texture in the 1.0% B-added sheet changed from gamma-fiber texture (as rolled) to the Goss texture {110}< 001 > (annealed). (c) 2008 American Institute of Physics.