Comparison of the material properties between magnetostrictive materials

A comparison of the material properties of various available magnetostrictive materials is shown in Table 32.1.

Table 32.1: Material properties of magnetostrictive materials and aluminium

Apart from Terfenol-D, the other smart materials included in the list are some of the more recent varieties in this field. Metglas or Vitrovac is a commercially available compound of iron (Fe), silicon (Si) and boron (B).
The other two materials consist of composites of Terfenol powders mixed with non-metallic binders. The binders work as insulating layers and effectively reduce the eddy current loss at higher frequencies of the applied magnetic field. The isotropic and anisotropic properties are attributed to random or biased magnetic dipole orientation of Terfenol powders during manufacturing. Table 32.1 shows that Terfenol-D rod produces the highest free-strain Λ . It is considered to be the most effective material from the point of view of actuation strain generation. However, it has poor tensile strength and it is the heaviest among the magnetostrictive materials.

On the other hand, Metglas possesses better mechanical properties, although it generates the lowest actuation strain. It is used mostly as a sensing material. In the two composite magnetostrictive materials, the energy conversion efficiency is quite low (k=0.28 and 0.40, respectively) rendering these unsuitable for low-frequency applications. Magnetostrictive materials with the capacity of high strain generation and wide bandwidth of operation promise wider applications in smart structures in near future.

Congratulations! You have finished Lecture 32.