Ferroelasticity

Ferroelasticity is a phenomenon in which a material may exhibit a spontaneous strain, and is the mechanical equivalent of ferroelectricity and ferromagnetism in the field of ferroics.

The application of opposite fields leads to Hysteresis as the system crosses back and forth across an energy barrier.

This transition dissipates an energy equal to the area enclosed by the hysteresis loop.

[3][4] In compatible materials, Raman spectroscopy has been used to directly image ferroelastic switching in crystals.

Nitinol (nickel titanium), a common ferroelastic alloy, can display either superelasticity or the shape-memory effect at room temperature, depending on the nickel-to-titanium ratio.

Left: An example free energy given by Landau's theory with two stable states. Transforming between states requires input energy which leads to hysteresis. Right: Example stress-strain hysteresis for a ferroelastic crystal.