Abstract
Nitinol is a kind of material with many properties to become useful in many applications. Shape memory effect and superelasticity are two of the main properties and the nature of them is phase transformation.
In this website, there will be a detailed description of key properties, applications, processing route, manufacture and safety information for Nitinol. Nitinol is non-toxic and harmless, with high resistance to corrosion. However, its mechanical properties have necessity for further improvement. Due to the features of the element, it needs to be processed in a vacuum environment and is more suitable for hot working. In addition, two products are displayed as samples to show the specific properties.
Key words: Nitinol, shape memory effect (SME), superelasticity
Introduction
Nitinol, the body centered cubic crystal material containing relative equal amount of nickel and titanium atoms, is the representative shape memory alloy (SMA) that has become a popular topic of research in these years. SMA is alloys with ability to “remember” their shapes after being plastically deformed. For nitinol, this effect is obtained by transformation between austenite and martensitic under heating or another external stimulus.[1] Additionally, Nitinol has a property of superelasticity which makes the material flexible for more possibilities for applications.
Literature Review
Nitinol is a kind of alloy with the shape memory effect (SME), which is an ability to “remember” the parent shape after being plastically deformed. Nitinol exhibits SME by reversible phase transformation between austenite and martensitic in the solid state. Because of the ability of memorizing shape, Nitinol also exhibits an ability of superelasticity. Combined with excellent biocompatibility and corrosion resistance, it has significant applications in biomedical field, aerospace industry and our daily life. Due to the specific characteristics of the elements, a vacuum or inert gas environment must be provided during the processing of Nitinol, and hotworking must be used when manufacturing. According to safety data sheet, Nitinol is a material with high safety and stability.It is hoped that this promising material can be used more efficiently and widely.
Nitinol Spring (Shape Memory Effect)
This is one of our sample, the Nitinol spring. It reflets the shape memory effect. The specific process will be shown in the video on the our sample page in the website, and below are some main screenshots that show the general situation.
Nitinol Wire (superelacticity)
The other sample for the Nitinol product is Nitinol wire, which shows the superelascticity perfectly. The specific process will be shown in the video on the our sample page in the website, and below are some main screenshots that show the general situation.
Property Profile
|
Physical Properties |
|
|
Density |
6.45 gm/cm3 |
|
Mechanical Properties |
|
|
Young's modulus |
approx. 83 GPa (austenite) |
|
Yield strength |
324 to 472 MPa (austenite) |
|
Tensile strength |
1.03e3 to 1.29e3 MPa (austenite) |
|
Poisson’s Ratio |
0.332 to 0.338 (austenite) |
|
Hot workability |
quite good |
|
Nitinol transformation properties |
|
|
Transformation temperature |
-200 to 110 ℃ |
|
Transformation strain |
4% (for 100,000 cycles) |
Table.1 Property profile of Nitinol.[15]
Poster of P39
Reflection
With the deep learning of the material of Nitinol, we consolidated our knowledge on Material Science. By finishing this project, we got more familiar with evaluating the material, and were more aware of the importance of material safety when applying. Websites to obtain the safety data sheet will be practical for our future study. To improve our work next time, we will use the way of online meeting to enhance the communication and association in each process of making the website.