Advanced Functionality of Shape Memory Materials

Advanced Functionality of Shape Memory Materials

(Yuko AONO)

Shape memory materials are highly functional materials that spontaneously recover their original shape under certain conditions after deformation. Shape memory materials are being studied as actuator materials because they not only simply recover their shape but also generate a force when they recover.

Laser Induced Local Bidirectional Drivability in TiNi Shape Memory Alloys

Conventional TiNi shape memory alloys recover shape and generate force above the transformation temperature. To solve this problem, research is being conducted on technologies that allow shape memory alloys themselves to be bi-directionally drivable, that is, to deform and generate force spontaneously during heating and cooling. However, the conventional bidirectional shape memory alloys have been achieved by introducing dislocations through aging treatment in a furnace or by strong machining, which is difficult to achieve for thin-film and localized shape memory alloys, as typified by the recent thin-film shape memory alloys.

Our group has been studying the selective bidirectional drive by local heat treatment using a laser. We have succeeded in developing bidirectional properties with very short-time laser irradiation, and have clarified the principle and the differences in bidirectional properties depending on the irradiation conditions.

Shape memory alloy strip that can be driven in both directions only by temperature control by irradiating a laser on the top surface.