When it comes to nickel-titanium alloys, a new term has to be introduced—shape memory alloys. Shape memory alloy refers to: a special alloy that can automatically restore its plastic deformation to its original shape at a certain temperature. Nitinol is this type of alloy. Nickel-titanium alloy has an expansion rate of more than 20%, a fatigue life of 1*10 to the 7th power, damping characteristics 10 times higher than ordinary springs, its corrosion resistance is better than the best medical stainless steel at present, so it can meet all The application requirements of engineering and medicine are very good functional materials. Next, let’s take a closer look at its performance!
Nickel-titanium alloy, as the name suggests, is a binary alloy composed of nickel and titanium.
Due to the change of temperature and mechanical pressure, they have two different crystal structure phases, namely austenite phase and martensite phase. The phase transformation sequence of the nickel-titanium alloy during cooling is the mother phase (austenite phase)-R phase martensite phase. The R phase is rhombohedral, and the austenite is at a high temperature (more than the same: the temperature at which austenite starts), or when the load is removed (external force is removed from Deactivation), it will be cubic, and the texture is hard and shape It is also relatively stable. The martensite phase is the state when the temperature is relatively low (less than Mf: the temperature at which the martensite ends) or loaded (activated by external force), it will appear as a hexagon, and it is malleable and repeatable, but The relative shortcoming is that it is less stable and more easily deformed.