Pseudoelasticity and the strain-memory effect in an Ag-45 at. pct Cd alloy

Application of Virtual Reality for Learning the Material Properties of Shape Memory Alloys

A shape memory alloy (SMA) is an alloy which can eliminate deformation at lower temperatures and restore its original shape upon heating. SMAs have been receiving considerable attention in the research field of materials science, and their applications include robotics, automotive, aerospace, and biomedical industries. Observing the SMA’s shaping and restoration processes is important for understanding its working principles and applications. However, the transformation of its crystal structure with temperature can only be seen using special equipment, such as a transmission electron microscope (TEM), which is an expensive apparatus and the operation requires professional skills. In this study, a teaching module is designed using virtual reality (VR) technology and research results of an SMA to show its shape memory properties, shaping and restoration processes, as well as the real-life applications in an immersive and interactive way. A teaching experiment has been conducted to analyze students’ learning effectiveness using the teaching module (the experimental group) compared with that of using real SMA materials as the teaching aids (the control group). Two classes of students in the Department of Materials Science (one as the experimental group and the other as the control group) were selected as the samples by convenience sampling from a university in North Taiwan. The experimental group contained 52 students and the control group contained 70 students. A nonequivalent pretest-posttest design was adopted to explore whether the two groups had a significant difference in learning effectiveness. The experimental results reveal that the teaching module can improve the learning effectiveness significantly (p = 0.001), and the questionnaire results also show that a majority of the students had positive attitudes about the teaching module. They believed that it could increase their learning motivation and help them understand the properties and applications of the SMA.

Shape-memory effect in an organosuperelastic crystal

An organoionic crystal of tetrabutyl-n-phosphonium tetraphenylborate thermally recovers its shape through superelasticity, similar to shape-memory alloys.

Shape-memory materials, i.e., polymers (SMPs: shape-memory polymers) and alloys (SMAs: shape-memory alloys), have been developed in very different ways since they are historically far apart in material type as well as physical property. In the deformation process, SMPs require only a slight stress due to the properties of organic polymer solids, and they reveal a smaller recovery force during the thermoplastic process whereas SMAs require a relatively large stress due to metallic properties, and they thermally tighten to generate a larger recovery force via destabilization of the stress-induced phase. An investigation into the unexplored area of the material adjoining both ends of SMPs and SMAs would lead toward a better understanding of shape-memory materials and extend future applications and material types. Here, we report the discovery of a shape-memory effect in an organic crystal bearing a combination of crystal transformability like in SMAs with organic components like SMPs.