Shape Memory Nitinol Wire

Features:

1. Ni-Ti alloy is a special alloy that can automatically restore its plastic deformation to its original shape at a certain temperature.

2. Its expansion rate is more than 20%, its fatigue life is 1 * 10 to the 7th power, its damping characteristic is 10 times higher than that of ordinary springs, and its corrosion resistance is better than the best medical stainless steel at present.

3. In addition to its unique shape memory function, memory alloy also has excellent characteristics such as wear resistance, corrosion resistance, high damping, and superelasticity

4. It is a very good functional material that can satisfy the application needs of different engineering and medical fields.

1. Shape memory is the ability of a material to deform at a temperature below Mf before being heated to a temperature above Af. This happens when the parent phase of a particular shape is cooled from a temperature above Af to a temperature below Mf to produce martensite. With reverse transformation, the material will automatically recover its shape at the parent phase. In fact, the shape memory effect is a thermally induced phase transformation process of Ni-Ti alloy.

2. The so-called hyperelasticity refers to the phenomenon that the strain produced by the specimen under the action of external force is far greater than its elastic limit strain, and the strain can automatically recover when unloading. That is, in the parent phase state, due to the effect of external stress, the stress-induced martensitic transformation occurs, so the alloy shows different mechanical behavior from ordinary materials, Its elastic limit is far higher than that of common materials, and Hooke's law is no longer observed. Hyperelasticity has no heat component as compared to shape memory capabilities. Simply said, hyperelasticity means that, within a specific deformation range, the stress does not rise with the increase in strain. Linear and nonlinear hyperelasticity are two different types of hyperelasticity. The connection between stress and strain on the former's stress-strain curve is essentially linear. The results of the stress-induced martensitic transformation and its inverse transformation during loading and unloading at a specific temperature range above Af are referred to as nonlinear hyperelasticity. Therefore, nonlinear hyperelasticity is also called transformation pseudoelasticity. The Ni-Ti alloy possesses a pseudoelasticity of phase change that can go up to roughly 8%. The superelasticity of nickel-titanium alloy can change with the change of heat treatment conditions; Above C, hyperelasticity begins to decline.

3. Some studies show that the corrosion resistance of Ni-Ti wire is similar to that of stainless steel wire.

4. Ni-Ti shape memory alloy has a special chemical composition, that is, it is a nickel-titanium and other atomic alloy, containing about 50% nickel, which is known to have carcinogenic and cancer-promoting effects. The broad barrier effect of titanium oxidation on the surface layer makes Ni-Ti alloy biocompatible. The release of Ni may be inhibited by TiXOy and TixNiOy in the surface layer.

Ni-Ti shape memory alloy wire needs to undergo multiple heat treatments and annealing during drawing production to eliminate its processing stress. Annealing will generate a dense oxide scale and appear black on the wire surface. Surface treatment is typically done between the drawing deformation and after drawing to eliminate the oxide scale on the surface in order to improve the wire surface quality and the wire appearance.

Medical nickel-titanium materials are composed of nearly equal atomic percent nickel and titanium, which comply with GB 24627 and ASTM F2063 and can be used for surgical implants. All products are processed to the final product using high-precision single-crystal or polycrystalline diamond drawing dies to achieve a uniform and smooth surface quality. After proper heat treatment, nickel-titanium material can withstand up to 8% strain at human body temperature without permanent bending.