Terfenol-D Magnetostriction
11 February 2008, 11:46
Categories: smt-polymorphic-shape-shifters smt-energy-piezoelectric
Magnetostriction is the property that causes certain ferromagnetic materials, such as ferromagnetic shape memory alloys, to change shape in a magnetic field. Terfenol-D, an alloy that is made of terbium, dysprosium, and iron metals, has the largest room temperature magnetostriction of any known material. Terfenol-D is said to produce “giant” magnetostriction, strain greater than any other commercially available smart material. Magnetic domains in the crystal rotate when a magnetic field is applied, providing proportional, positive and repeatable expansion in microseconds.
While most attention has been focused on how electricity can be used to induce changes in shape that can do mechanical work, some have begun to exploit the reverse phenomenon of the material, commonly called to Villari Effect, wherein mechanical work is converted into electrical energy. Rather than having an external magnetic field force the rotation of magnetic domains to deform the crystal to do mechanical work, devices can be made where mechanical vibrations or loads deform the crystal and, in doing so, rotate the magnetic domains, which generates a transient current.
Posted by: The Editors
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