| Summary: | 碩士 === 國立宜蘭大學 === 化學工程與材料工程學系碩士班 === 106 === The first part of this study is to investigate the selective leaching properties of Cu-XAl-4Ni (X=12.5、13.0 and 13.5) shape memory alloys (SMAs). According to the XRD, DSC, and SEM results, the Cu-XAl-4Ni SMAs were in the (18R) martensite phase at room temperature. The electrochemical result reveals that there were no obviously different from each other in the corrosion resistance of the Cu-XAl-4Ni SMAs in Ringer’s solution. The ICP-MS result indicates that the Ni ions after Cu-XAl-4Ni SMAs immersion in Ringer’s solution for 90 days were higher than Cu and Al ions. The low concentrations of Cu and Al ions stem from the oxidation of Cu and Al atoms near the surface of the Cu-XAl-4Ni SMAs to form Cu2O and Al2O3 films, but there were no NiO film formed on the surface of the Cu-XAl-4Ni SMAs. The selective leaching properties of the Cu-XAl-4Ni SMAs were inferior to that of the TiNi SMA but were much better than those of the TiNiCu and TiNiFe SMAs. Cu-XAl-4Ni SMAs are potential candidates to serve as biomaterials owing to their lower cost, better workability, and more easily obtainable desirable martensitic transformation temperatures by adjustment of the chemical composition of the alloys.
In the second part of this study, we investigate the damping capacities of the inherent and intrinsic internal frictions (IFPT+IFI) of Ni50Mn40-xSn10+x (x = 0、0.5、1、2、3 and 4) ferromagnetic shape memory alloys (FSMAs). According to the DMA result, the damping capacities of the (IFPT+IFI)L21→14M peaks of the Ni50Mn40Sn10 and Ni50Mn39.5Sn10.5 FSMA are higher than those of the other Ni50Mn40-xSn10+x FSMAs, which exhibit (IFPT+IFI)L21→14M(dominant)+10M(partial), (IFPT+IFI)L21→10(dominant)+14M(partial), or (IFPT+IFI)L21→4O peaks, as there are more abundant movable twins dissipating energy during damping in the 14M martensite than in the 10M or 4O martensite. The Ni50Mn38Sn12 FSMA exhibits a lower (IFPT+IFI)L21→10(dominant)+14M(partial) peak than the (IFPT+IFI)L21→4O peak of the Ni50Mn37Sn13 and Ni50Mn36Sn14 FSMAs as there is a smaller number of movable twins in the 10M martensite than in the 4O martensite. Compared with other SMAs, the Ni50Mn40-xSn10+x FSMAs with the 14M martensite structure not only exhibit a high damping at a temperature above 100°C, but also possess the advantages of unique magnetic properties, low cost, and simple control of the desired martensitic-transformation temperature by adjusting the chemical composition of the alloy.
|
|---|
