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Nitinol: The Magical Metal with Memory

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Update time : 2020-07-31 09:13:07

Metal with "Memory"

It's not uncommon for people to have memories, but if metals had memories, it would be amazing! This magical metal is called "shape memory alloy"!

Shape memory alloy (SMA), as the name suggests, is an alloy material with "memory" effect. It can remember its initial shape and has the function of sensing and driving at the same time. It is a kind of intelligent material.

No matter how the shape memory alloy deforms, it will magically return to its original shape after being heated to a certain temperature. It can undergo phase transition under the action of temperature and stress. Such metal has unique shape memory effect, phase transition pseudo-elasticity and other characteristics, and is the most critical material for 4D printing.

Ordinary metal, once formed into a spoon, will always be a spoon. We can bend the spoon with pliers and it will turn into a useless pile of metal pieces. But if the spoon is made of shape memory alloy, bending the spoon and reheating it will restore its original shape, which gives it many magical uses.

Up to now, dozens of kinds of shape memory alloys have been discovered in the world, among which nitinol is the earliest developed and the most practical alloy material.

Two crystal structures of SMA materials are called austenite and Martensite. The former is the SMA at higher temperature, while the latter is the SMA at lower temperature. The transition from austenite to martensite is the reason for this "memory" property (and vice versa).Common materials for SMA include cu-Al-nickel and Nitinol, often referred to as Nitinol, referring to its element composition (Ni for nickel, TI for titanium) and the place where it was first discovered (NOL for Naval Weapons Laboratory).

The Discovery of Shape Memory Alloys

There is another story about the discovery of the properties of SMA materials. Early research into the material began in the 1930s, when scientists studied some unexpected properties of different metals. Swedish chemist Arne Olander described a pseudo-elastic phenomenon discovered while looking at gold-cadmium alloys. However, it was not until a laboratory accident some 30 years later that the term "shape memory alloy" was actually used...

By the late 1950s and early 1960s, metallurgical research was being conducted at the U.S. Naval Weapons Laboratory. One day, a scientist named William J. Buehler was smelting and casting nickel-titanium rods. While waiting for the rods to cool, he dropped one on the concrete floor and heard a dull thud. He thought this was strange, and then he dropped a hot nickel-titanium stick on the floor, too, when he heard a ringing sound like a bell. Buehler was worried that something was wrong with the casting process, so he went to the water cooler and put the hot niti bar in cold water to cool it. Then he dropped the freshly cooled nickel-titanium rod to the ground, and again he heard a dull thud.

This effect was later confirmed at a meeting of the Naval Weapons Laboratory. Buehler's assistant handed out thin strips of Nitinol that had been stretched, bent and folded like an accordion. When Dr. David S. Muzzey got hold of the bar, he took out a lighter and heated it. The bar quickly unfolded and returned to its original thin shape. After recognizing the properties and properties of Nitinol at different temperatures, people called the material Nitinol, which is a SMA.

From the perspective of recent and future development trends, shape memory materials are no longer limited to alloys. Shape memory polymers and various other forms of shape memory materials have been developed and used for various commercial purposes.

Application of Shape Memory Alloy

Nitinol alloy has a series of excellent properties, which make it widely used in aerospace, automobile industry, medical equipment and other fields. More recently, shape memory materials have been used in consumer electronics. For example, the AUTO focus component for smartphone cameras and some mobile antennas are made with SMA.

Even some crafts and toys use SMA, for example, "flexible bracelets," which are made from shape memory materials that can be bent and twisted and then easily return to their original shape.

The Future of Shape Memory Alloys

The shape memory alloy industry is one of the seven emerging industries in line with the national strategic emerging industry plan and the supporting policies of the central and local governments. It is also one of the industries supported and encouraged by the state.

In the future, with the development of shape memory alloy technology, and reduced cost, industrial policy to promote and improve consumer acceptance, shape memory alloy will be more close to people's lives, in addition to the car, robots, household appliances, medical equipment and other products, part of life's little items will also popularize the application of shape memory alloy, will drive the shape memory alloy to further expand the size of the market.

TRUNNANO (aka. Luoyang Tongrun Nano Technology Co. Ltd.) is a trusted global chemical material supplier & manufacturer with over 12 years’ experience in providing super high quality chemicals and Nano materials. The Nitinol produced by our company has high purity, fine particle size and impurity content. Lower, please contact us if necessary.

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