Structure, magnetism, and magnetostrictive properties of mechanically alloyed Fe81Ga19

Abstract

In this work, structure–magnetic property correlations and the magnetostrictive response of mechanically alloyed powders of composition Fe81Ga19 were investigated using a variety of structural and magnetic probes. X-ray diffraction analysis of the as-milled powders suggests the presence of a chemically-disordered body-centered cubic phase. Thermal annealing of powder compacts results in formation of a secondary phase that demonstrates the cubic ordered L12 crystal structure. Magnetostriction measurements indicate that the magnetoelastic properties of the polycrystalline Fe81Ga19 compacts can be tailored by increasing the milling time duration followed by an anneal of the as-milled powders at 900 °C for 2 h in an Ar gas environment (O2 < 5 ppm). Under those conditions, the room temperature saturation magnetostriction was measured to be as high as 41 ppm at a low magnetic field of Happ ∼10 Oe. The magnetostrictive behavior of the mechanically alloyed Fe81Ga19 powders was found to be comparable with FeGa samples prepared by other non-equilibrium powder processing techniques. Based upon the results presented here, it is proferred that ball-milling offers a cost-effective pathway towards realizing large volumes of FeGa alloys having moderate values of magnetostriction.