Ferroelasticity
Ferroelasticity is a phenomenon in which a material may exhibit a spontaneous strain. In ferroics, ferroelasticity is the mechanical equivalent of ferroelectricity and ferromagnetism. When stress is applied to a ferroelastic material, a phase change will occur in the material from one phase to an equally stable phase, either of different crystal structure, or of different orientation. This stress-induced phase change results in a spontaneous strain in the material.
The shape memory effect and superelasticity are manifestations of ferroelasticity. Nitinol, a common ferroelastic alloy, can display either superelasticity or the shape-memory effect at room temperature, depending on the nickel-to-titanium ratio.
