Two main smelting methods of nitinol memory alloy

Overview of Nitinol alloy powder

Nitinol, also known as Nitinol, is a metal alloy of nickel and titanium, in which the atomic percentages of the two elements are approximately equal. Different alloys are named according to the weight percentage of nickel (such as nickel). Nitinol 55 and Nitinol 60. Show shape memory effect and super elasticity at different temperatures.

Nitinol is a shape memory alloy, a special alloy that can automatically restore plastic deformation to its original shape at a certain temperature. The expansion rate exceeds 20%, the fatigue life is 7 times that of 1*10, and the damping characteristic is 10 times. Compared with ordinary springs, its corrosion resistance is better than the best medical stainless steel at present, so it can meet a variety of engineering requirements and is an excellent functional material that can meet the needs of medical applications.

In addition to its unique shape memory function, memory alloy also has excellent properties such as wear resistance, corrosion resistance, high damping, and super elasticity.

Nitinol has two closely related and unique properties: shape memory effect and superelasticity (also known as pseudoelasticity). Shape memory is the ability of Nitinol to deform at a certain temperature, maintain its deformed shape after the external force is removed, and then return to its original shape. It does not deform when heated above its "transition temperature". Superelasticity is the ability of a metal to withstand large deformations and immediately restore its undeformed shape after the external load is removed. The deformation of Nitinol is 10 to 30 times that of ordinary metals and can restore its original shape.

Two main smelting methods of Nitinol alloy powder

Whether Nitinol alloy shows shape memory effect or superelasticity depends on whether it is higher than the transition temperature of the specific alloy. Below the transition temperature, it exhibits a shape memory effect.

The production of Nitinol is extremely difficult due to the need for very strict composition control and excellent titanium reactivity. Every atom in titanium that binds to oxygen or carbon is taken out of the nickel-titanium lattice, thereby changing the composition and lowering the phase transition temperature. There are two main melting methods: 

Vacuum arc remelting (VAR)

This is achieved by creating an arc between the raw material and the water-cooled copper contact plate. The melting is done under high vacuum, and the mold itself is water-cooled copper.

Vacuum induction melting (VIM)

This is done by heating the raw material in a crucible (usually carbon) using an alternating magnetic field. This is also done under high vacuum.

Although these two methods have their own advantages, it has been proved that compared with the VART smelting process, the VIM smelting process has fewer material inclusions and therefore has higher fatigue resistance. Other research reports pointed out that the use of ultra-high purity plasticizers in raw materials can reduce the number of inclusions and improve fatigue performance. Other methods can also be used on a boutique scale, including plasma arc smelting, induction head shell smelting, and electron beam smelting. Physical vapor deposition is also used on a laboratory scale.

The hot processing of Nitinol alloy is relatively easy, and cold processing is more difficult, because the huge elasticity of the alloy increases the contact between the mold or the roller, resulting in huge frictional resistance and tool wear. For the same reason, processing is very difficult, and what's worse is that Nitinol has very poor thermal conductivity, so it is difficult to dissipate heat. Grinding (abrasive cutting), electrical discharge machining (EDM) and laser cutting are all relatively easy.

Application of Nitinol Alloy Powder

Nitinol powder can meet the needs of various engineering and medical applications and is an excellent functional material. In addition to its unique shape memory function, memory alloy also has excellent functions such as wear resistance, corrosion resistance, high damping and super elasticity.

The tensile strength of Nitinol can reach 1000 MPa, which means that it takes more than 100 dry grams per square millimeter to destroy it. This force is stronger than ordinary steel, and it also has good "memory" performance and corrosion resistance.

Nitinol alloy contains 50% nickel and 50% titanium, that is, nickel and titanium are equally divided, each accounting for half. The temperature range of the shape memory can be adjusted by the control element. Generally, the higher the nickel content, the lower the working temperature. When it contains 55% nickel and 45% titanium, the memory alloy can work at room temperature.

People made use of this characteristic of shape memory alloy to make pearl necklaces and bracelets made of shape memory alloy wire, and bras made of shape memory alloy wire. Wearing these decorations and health products on the body will restore the original curvature and rigidity under the action. Body temperature, which plays a role in decoration and health care. In addition, you can also use nickel-titanium alloy to make orthodontic wires to correct deformed teeth according to the body's oral temperature.

Nitinol can be used to replace traditional actuators (solenoid valves, servo motors, etc.), such as the simple hexapod robot Stiquito.

Nitinol springs are used in fluid thermal valves, and their materials can be used as temperature sensors and actuators.

The alloy is used as an auto-focus actuator in sports cameras and an optical image stabilizer in mobile phones.

Alloys are used in pneumatic valves to obtain a comfortable seat, which has become an industry standard.

The alloy Chevrolet Corvette contains a nickel-titanium memory alloy actuator, which replaces the heavier electronic transmission, used to open and close the hatch to release air from the torso, making it easier to access.

Nitinol powder price

The price of Nitinol powder varies randomly with changes in production costs, transportation costs, international conditions, exchange rates, and the supply-demand relationship of the Nitinol powder market. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for Nitinol alloy powder materials, please feel free to contact to get the latest price of Nitinol alloy powder.

Nitinol powder suppliers

As a global nitinol powder supplier, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including water-based stearic acid emulsion, water-based calcium stearate, zinc stearate, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.