Design And Study On The Cu-based Shape Memory Alloy

The research on the new functional material has been one of the focuses of the material research field in recent years, and shape memoryalloys are studied more among them. Shape memory effect is formed through phase transformation inducted by the temperature or the press. Cu-Zn-Al alloy is another kind of useful shape memory alloy following Ni-Ti alloy. The crucial parameters for engineering application of copper-based shape memory alloys are shape memory effect and its stability. Compared with Ni-Ti alloys, Cu-based alloys have such advantages as the wide sources of raw materials, simple preparation technology, low cost, wide range of transformation temperature, good electric conduction and so on.Morphology, substructure, and crystal structure of martensite as well as the influence of different heat treatment on transformation temperature and shape memory effect in the Cu—Zn—Al shape memory alloy are studied in this paper by means of Optical Microscope, XRD, Transmission Electron Microscope(TEM) and so on.The alloy with the composition of Cu— 26.12Zn— 4.83A1 quenched at high temperature directly has fine shape memory effect and its shape memory effect is better than other alloy with similar composition. The microstructure is lath-like martensite. Ageing at room temperature, there is no stability of martensite. They are parallel distributed mostly. The substructure is stacking fault. The stabilization of martensite do not happen when aged at room temperature for a long time, so it has utility value.The experimental results indicate that the transformation temperature of aged alloys are generally higher than that of quenched directly. The content of thermalelastic martensite in the sample increases as the quenching temperature. A large amount of lath-likemartensite appears after quenched from 850℃, and drops again when above 850℃. Shape memory effect also reaches the peak value at 850℃. Shape memory effect of the aged sample is better than that only quenched directly. Bainite transformation happens when aged at higher temperature, so the shape memory effect decreases.