Magnetostriction of stress-annealed Fe-Ga and Fe-Ga-Al alloys under compressive and tensile stress

The addition of Al and Ga to b.c.c. alpha-Fe increases the magnetostriction of Fe in the [100] direction (a factor of 12 for Fe81Ga19). The Fe-based magnetostrictive materials are machineable, mechanically tough, and saturate in fields of only a few hundred Oersteds, even under compressive loads up to -97 MPa. The effect of annealing single crystal Fe86.9Ga4.1Al9.0 and Fe86.9Ga8.7Al4.4 and polycrystalline Fe81.6Ga18.4 rods under compressive stress of 100 MPa for 10 min at temperatures between 625 and 750 degrees C were examined. After annealing, all samples showed nearly full performance at near-zero stresses and tensile stresses up to approximate to 20MPa, allowing tough wide-bandwidth magnetomechanical devices.