MAGNETOSTRICTION AND MAGNETOMECHANICAL COUPLING IN AMORPHOUS RARE EARTH-IRON COMPOUNDS

The effects of additions of the rare earths (RE) terbium and samarium on the room temperature magnetoelastic properties of amorphous Fe0.82B0.18 and Fe0.90Zr0.10 have been studied for up to 50 and 10 at. % RE, respectively. As the RE content in the Fe-Zr compounds is raised, the relative permeability increases, as do the Curie temperature, magnetostriction and magnetomechanical coupling. The magnetic phase diagram for Fe-Zr-RE derived from magnetization data indicates the transition to a random anisotropy phase, evident at low temperatures in Fe0.90Zr0.10, rapidly rises to near room temperature with the addition of Tb and approaches the Curie temperature near approximately 9 at. % Tb. This pattern of behavior is not seen in the Fe-B-RE compounds in which the exchange dominated behavior at room temperature remains essentially unchanged and is accompanied by reductions in permeability and magnetostriction until more than approximately 18 at. % RE is included.