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Shape memory alloys are often classified according to the type of matrix. It is mainly divided into nickel-titanium base, copper base and iron base shape memory alloys.
(1) Nickel-titanium base: Nickel-titanium alloy has the main advantages of long fatigue life, biocompatibility and superior mechanical properties, so this kind of material is long as the memory material of the actuator, and also has great application prospects in the biomedical field. Among them, Ni-Ti, Ni-Ti-Cu and Ni-Ti-Fe are the most common.
(2) copper base: copper base compared with nickel-titanium base, has many advantages, the first is cheap, the second copper-based production process is more simple, good thermal processing, its thermal conductivity is higher than nickel-titanium base, in communication engineering, machinery manufacturing, construction industry has certain advantages. The typical ones are Cu-Zn-Al, Cu-Ai-Ni and Cu-Al-Mn.
(3) Fe-based: Fe-based shape memory alloy is different from the above two, and its memory effect is the forward and inverse martensite transformation caused by stress induction. The iron base has low price, high strength and good processing plasticity, but the shape memory effect is relatively poor. The development of new Fe-based memory alloy materials, such as Fe-Ni-Co-Al-Ta-B, makes Fe-based memory alloy have more extensive application prospects.
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