Nitinol is a shape memory alloy. Shape memory alloy is a special alloy that can automatically restore its own plastic deformation to its original shape at a specific temperature, and has good plasticity.
Its expansion rate is above 20%, fatigue life is up to 7 times of 1*10, damping characteristics are 10 times higher than ordinary springs, and its corrosion resistance is better than current medical stainless steel, so it can meet the needs of various engineering and medical applications, and it is a kind of excellent functional material.
In addition to the unique shape memory function, memory alloys also have excellent characteristics such as wear resistance, corrosion resistance, high damping and super elasticity.
(I) Phase Transformation and Properties of Nickel-Titanium Alloys
As the name suggests, Ni-Ti alloy is a binary alloy composed of nickel and titanium, which exists two different crystal structure phases, austenite and martensite, due to the change of temperature and mechanical pressure. The order of phase transformation of Ni-Ti alloy when cooling is parent phase (austenite phase) – R phase – martensite phase. The R phase is rhombic, austenite is the state when the temperature is higher (greater than the same: i.e., the temperature at which austenite begins), or de-loaded (external forces remove Deactivation), cubic, hard. The shape is more stable. The martensite phase is relatively low temperature (less than Mf: that is, the temperature of the end of the martensite) or loading (activated by external forces) when the state, hexagonal, ductile, repetitive, less stable, more prone to deformation.
(B) special properties of nickel-titanium alloy
1, shape memory characteristics (shape memory)
2、Superelasticity (superelasticity)
3、Sensitivity to temperature change in the oral cavity.
4、Corrosion resistance:
5, Anti-toxicity:
6, Soft orthodontic force
7、Good shock absorption properties
Post time: Mar-14-2024