Terfenol-D

OBS: Le Terfenol-D, alliage de métaux de faible résistance électrique, développe des courants de Foucault lorsque la fréquence de vibration augmente, d'où des pertes. [...] Autre inconvénient du Terfenol-D : son coût élevé, obstacle qui pourrait être surmonté grâce à des alliages à base de terres rares moins chères.

OBS: Users of permanent magnets know of the very high magnetic coercivity exhibited by certain rare earth-iron alloys, most commonly neodymium-iron-boron ... but also including such other rare earth elements as dysprosium for higher anisotropy ... Very similar alloys have been developed which excel in related magnetic properties. Take for example, the alloy with terbium and dysprosium commonly known as Terfenol-D ... which exhibits a very high magnetostriction; this alloy is said to have ""Giant"" Magnetostriction.
OBS: ... a miniature actuator ... utilizes a Terfenol-D rod; only the end of the rod is visible, attached to a metal dome for actuation. The length of the rod changes as current is applied to the coil surrounding it. The housing acts as part of the magnetic circuit, which also includes a conventional permanent magnet for biasing (not visible). Thus, actuation is provided only by the changing length of the rod, although some mechanical amplification (e.g.: using a lever arm) may be advantageous.
OBS: Magnetostrictive material, such as these Terfenol-D rods that are several centimeters long, changes its length in a magnetic field. Originally developed for military sonar, the alloy is finding use in actuators, vibration controllers and sensors.