Magnetostriction of Terfenol-D, heat treated under compressive stress

Heat treatment at temperatures > 835 degrees C and compressive stresses > 8 0 MPa substantially increased the magnetostrictive performance of Terfenol- D (Tb0.3Dy0.7Fe1.92) under the condition of zero loading. This heat treatme nt created a built-in prestress which significantly increased the low stres s magnetostriction and substantially altered the magnetization curve by red ucing its initial susceptibility. For measurements at compressive stresses > 15 MPa the effect of the built-in stress was minimal and the magnetostric tive performance was not appreciably altered.