The discovery of low-temperature magneto-elasticity in rare-earth elements like Tb (Terbium), Dy (Dysprosium) and Sm (Samarium) has given a fresh impetus to the scientists to search of magnetostricitive (MS) materials suitable for developing transducers. Clark et al [1983] have obtained room temperature magnetostriction in the alloy of Tb and Fe which has higher Curie temperature (around 7000 K). Subsequently, it was found that by adding another rare-earth material called Dysprosium with Tb-Fe alloy the magnetic anisotropy in the alloys can be reduced, thus generating even larger strains. Terfenol compound made using the composition Dy_0.73Tb_0.27Fe_1.95   produces less sharp but more linear variation of strain than the same compound made of Dy_0.7Tb_0.3Fe_1.95 composition [Greenough et al, 1991]. Substituting Dysprosium from Tb-Fe alloy by other rare earth materials like Holonium or Samarium, magnetostriction characteristics can be significantly changed.

Material properties of two important Magnetostrictors with Aluminum are listed in Table 12.1.

Table 12.1: Material properties of two different magnetostrictors and Aluminum [Butler, 1988]