Rare Earth Transition Metal Based Giant Magnetostrictive Materials: An Interdisciplinary Perspective

Abstract

Magnetostriction is a unique property of magnetic materials where in the dimensions of the material changes due to the application of an external magnetic field. Of the several magnetic materials studied until now, rare earth (R) transition metal based RFe2 type alloys exhibit giant magnetostriction at room temperature. As a potential candidate for transducer and actuator applications, research and development of RFe2 alloys were mainly focused on anisotropy compensation, optimization of composition and grain orientation in order to achieve large magnetostriction at low magnetic fields. Large magnetostrictive strains at low magnetic fields have been found to be strongly influenced by the phases present in the microstructure and crystallographic texture. Adopting directional solidification techniques and selective alloying additions at rare earth and transition metal sites has been found to be beneficial in inducing the necessary texture and precluding the formation of deleterious phases in the microstructure. In this context, this chapter attempts to address the evolution of microstructure and texture upon directional solidification in RFe2 alloys. In addition to this, effect of alloying addition on the microstructure and magnetostrictive properties of RFe2 are also presented.