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When was Shape memory alloys discovered?

  What is a shape memory alloy? Shape memory alloys  (SMAS for short) are alloys with”memory”: they can be restored to their original shape after deformation by pressure or temperature changes. SMA has a wide range of applications, including metallurgy, manufacturing, biomedicine and children’s handicrafts, its range of applications continue to expand to a variety of fields. Shape memory alloys are materials that undergo phase transitions when subjected to mechanical stress or temperature changes. The SMA will “remember” its original shape and revert to its original shape when the condition returns to normal. The two crystal structures of SMA materials are called austenite and martensite. The former is the structure of the SMA at a higher temperature, the latter is the structure at a lower temperature. The transition from austenite to martensite is the cause of this”memory”characteristic. Commonly used materials for SMA include copper-aluminum-nickel alloys and nickel-titanium alloys.
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Why is Nitinol used for braces?

  Biocompatible Nitinol shape memory alloy has a special chemical composition, that is, it is an atomic alloy such as nitinol, which contains about 50% nickel, and it is only known that nickel has carcinogenic and carcinogenic effects. Under normal circumstances, the oxidation of titanium on the surface layer acts as a barrier, making  Ni-Ti alloys biocompatible . TIXOY and TIXNIOY in the surface layer can inhibit the release of Ni. Nitinol Super Elastic The so-called superelasticity refers to the sample under the external force of the strain is much greater than the elastic limit strain, the phenomenon of automatic recovery of the strain when unloaded. That is, in the state of the parent phase, due to the effect of the applied stress, stress-induced martensitic transition occurs, so that the alloy exhibits mechanical behavior different from ordinary materials. Its elastic limit is much larger than ordinary materials and no longer obeys Tiger K’s law. Compared to shape memory performa
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Why does nitinol have shape memory?

  Nitinol is a   shape memory alloy ,it is a special alloy, at a certain temperature can automatically restore its plastic deformation to its original shape. Its expansion rate of more than 20%, fatigue life of up to 1×10 to 7 power,damping characteristics are 10 times higher than ordinary springs, corrosion resistance is better than the best medical stainless steel, can meet a variety of engineering requirements, is the best choice for   medical applications . Nitinol grades TiNi-01 Phase change temperature: 20℃-40℃ TiNi-02 Phase change temperature: 45℃-90℃ TiNi-SS Phase change temperature: 5℃-15℃ TiNi-YY Phase change temperature:33℃±3℃ TiNiCu phase change temperature: As-Ms≤5℃ TiNiNb Phase change temperature:As-Ms Nitinol is a binary alloy consisting of nickel and titanium. Due to changes in temperature and mechanical pressure, there are two different crystal structure phases, namely Austenite phase and martensite phase. The phase transition sequence of Nitinol cooling is the parent
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What are the disadvantages of Nitinol?

  1.Nitinol Biocompatibility As a long-term implantation of human biomaterials (such as heart stents), nitinol memory alloys must not only have good biomechanical functions, but also have good corrosion resistance and biocompatibility. Although Nitinol memory alloy has made great strides in the  medical field , since nitinol memory alloy still contains nearly 50%of nickel, nickel is a potential carcinogen and allergen, nitinol memory alloy as a long-term but also a large number of nickel present in stainless steel and cobalt-chromium alloy. With proper treatment (by electro-polishing or passivation) Nitinol, a very stable titanium dioxide protective layer will be formed on the surface of Nitinol, acting as a very effective and self-healing barrier, hindering the exchange of nickel ions. Experiments have repeatedly shown that Nitinol releases nickel ions slower than stainless steel. No significant corrosion or nickel release was observed in today’s nitinol memory alloy vascular stents,
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What is nitinol and where is nitinol used?

When it comes to shape memory alloy, many people have heard of its name. No matter how deformed it is, after heating to a certain temperature, it can magically change back to its original shape. So far, dozens of shape memory alloys have been found in the world. Nitinol is one of the earliest developed and most practical alloy materials. Nitinol special properties Nitinol is a binary alloy consisting of nickel and titanium. In addition to its unique shape memory function, it also has a series of excellent properties, is a very good functional material. 1.Shape memory characteristics. Nitinol alloys are deformed by external forces at a certain temperature. After the external force is removed, the shape of the deformation can still be maintained,but at higher temperatures can automatically return to the original shape. 2.Super elastic. The superelastic energy of nitinol varies with the heat treatment conditions. When the nitinol wire is heated to more than 400℃, the superelasticity begin
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