Magnetorestrictive

Magnetorestrictive is an adjective describing materials that change shape or dimensions when subjected to a magnetic field. This phenomenon is known as magnetostriction. Conversely, the inverse effect, where a material undergoes a magnetic change when subjected to mechanical stress, is called the Villari effect or the magnetoelectric effect.

Materials exhibiting magnetorestrictive properties are typically ferromagnetic. The most common magnetorestrictive materials include iron, nickel, cobalt, and their alloys such as Permalloy and Terfenol-D. The magnitude of the change in shape is usually small, but it is a measurable effect. The deformation can be either positive (expansion) or negative (contraction) depending on the material and the direction of the magnetic field relative to the material's magnetic domains.

The underlying mechanism of magnetostriction involves the rearrangement of magnetic domains within the material in response to an external magnetic field. As the magnetic domains align with the applied field, the material's atomic structure is slightly distorted, leading to a macroscopic change in its dimensions.

Magnetorestrictive materials have practical applications in various devices. They are used in actuators, which convert magnetic energy into mechanical motion, and in sensors, which detect magnetic fields by measuring the resulting deformation. Examples include sonar transducers, vibration generators, and precision positioning systems. The development of new magnetorestrictive materials with enhanced properties continues to be an active area of research.