Shape-memory alloys are a new generation of smart materials in applied science with the hope of replacing stainless steel in medicine.
Shape Memory Alloy
Shape memory alloy (SMA) is a new generation of smart materials being researched and gradually put into use in the world. Objects made from SMA material, after being deformed by an external force, will restore their original shape.
An example to make it easy to imagine: we have a spring made of Nitinol (SMA) that, after being straightened, bent or twisted into different forms, dropped into a basin of hot water, will return to its original shape. in just a few seconds.
How do metal mnemonic alloys work?
Development history
The shape memory (SME) effect of alloys was first noted in the 1930s. In 1961, William J. Buehler, a researcher at the Naval Ordnance Laboratory, discovered the shape memory effect in Ni- alloys. Ti. Dogs to this day, this is still the most studied and widely applied SMA material in many fields.
Another new type of SMA was discovered later, called a magnetic shape memory alloy (MSMA). They can change shape under strong magnetic fields. These materials are of great interest to researchers because magnetic-induced reactions tend to be faster and more efficient than temperature-induced reactions.
Application
Currently, the two most common types of SMA are Ni-Ti and Au-Cd.
Ni-Ti (Nitinol) shaped memory alloy has very good mechanical and electrical properties, non-magnetic, high strength and corrosion resistance, especially biomedical compatibility. This material is said to have the potential to completely replace stainless steel in the future. Therefore, this is considered a versatile material with many applications in medicine (orthopedic surgery, heart valve devices, dilation valves…), aerospace industry (antenna, battery opening and closing mechanism. sun…), robotics or engineering groups.
The Au-Cd alloy system is the opposite. They are mainly used in the field of research and determination of the crystal structure of materials to determine the cause of their properties.
In Viet Nam
In Vietnam, it is still a relatively new field. Therefore, the manufacturing, production and application of this smart alloy in our country is very limited. In 2019, Prof. Dr. Nguyen Huy Dan and his colleagues at the Institute of Materials Science, Vietnam Academy of Science and Technology started researching and manufacturing SMA.
In March 2021, this research group succeeded in making an alloy with the ability to remember shapes. This material is studied on three different alloy systems including Nitinol alloy system, Heusler alloy system including (Ni, Co)-Mn-(Ga,Al) and high entropy alloy system including Ti-Zr-( Co,Hf)-Ni-Cu. The successful research and manufacture of this alloy has opened up a new direction for the study and development of smart materials in our country.