Shape Memory Alloys

They have the characteristics of high elasticity, metal rubber performance, high strength, etc., and after plastic deformation at a lower temperature, they are heated and restored to the shape before heating. Alloys such as Ni-Ti, Ag-Cd, Cu-Cd, Cu-Al-Ni, Cu-Al-Zn, etc., can be used to adjust the elastic components of the device (such as clutches, throttles, temperature control elements, etc.), heat engines Materials, medical materials (orthodontic materials), etc.

The shape memory effect is derived from a thermoelastic martensitic transformation. The general martensitic transformation is a method of quenching and strengthening steel. It is to heat the steel to a certain critical temperature for a period of time and then to cool it quickly, for example, directly into cold water (called quenching), when the steel is transformed into one. The structure of the martensite and harden the steel. Later, another so-called thermoelastic martensitic transformation different from the above was found in some alloys, and once produced, the thermoelastic martensite can continue to grow with decreasing temperature. Conversely, when the temperature rises, the grown martensite can be reduced again until it returns to its original state, that is, the martensite can reversibly grow or shrink with temperature changes. The thermoelastic martensitic transformation is accompanied by a change in shape.

In addition to the above categories, new metal functional materials include vibration-damping alloys that reduce noise; biomedical materials that replace, enhance, and repair human organs and tissues; and implant sensors, signal processors, and communications in materials or structures. With the controller and actuator, the material or structure has self-diagnosis, self-adaptation, and even smart materials such as self-healing intelligent functions and vital signs.