Nitinol Jewelry

The so-called superelasticity refers to the phenomenon that a sample produces a strain far greater than its elastic limit strain under the action of external force, and the strain can automatically recover when unloaded. That is, in the parent phase state, due to the action of external stress, stress-induced martensite transformation occurs, so the alloy exhibits mechanical behavior different from ordinary materials. Its elastic limit is much larger than that of ordinary materials, and it no longer obeys the Hu Gram's law. In contrast to shape memory properties, superelasticity has no thermal involvement.

The shape memory of Nitinol is that after the parent phase of a certain shape is cooled from above the Af temperature to below the Mf temperature to form martensite, the martensite is deformed at a temperature below Mf and heated to the Af temperature. Next, with the reverse phase transformation, the material will automatically restore its shape in the parent phase. In fact, the shape memory effect is a thermally induced phase transformation process of nitinol alloy.