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. 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 100MPa for 10 min at temperatures between 625 and 750 C were examined. After annealing, all samples showed nearly full performance at near-zero stresses and tensile stresses up to 20 MPa, allowing tough wide-bandwidth magnetomechanical devices.