00000ctmaa22000004a 4500 UP-99796217609940154 Buklod 20110714161912.0 m |o d | ta 110714s2004 xx d r |||| u| (iLib)UPD-00177203281 DENG eng DMLUC LG 996 2004 M37 A24 Abellana, Virgilio Y. Development of a copper-tin shape memory alloy Virgilio Y. Abellana. 2004. xxv, 198 leaves ill. (some col.) + 1 CD-ROM (4 3/4 in.) "May 2009." Thesis (Ph.D. Materials Science and Engineering)--University of the Philippines Diliman. The family of shape memory alloys, (SMAs), having anthropomorphic qualities has found many applications in industry and medical science. Copper-Tin SMA is one of the most promising members of the family because of its price advantage over Ni-Ti. However, it is among the least studied and has problems in its ductility and workability.. Chemical, physical and shape behavior data are needed for any eventual design-applications and fabrications. Copper-Tin SMA was synthesized by melting pure copper and pure tin in a graphite mold heated a tube furnace. Several compositions were tried and heat-treated to produce thermoplastic martesite or Yi phase. X-ray diffraction data showed that at 16 atomic % Sn pure Yi'phase was produced. Compositions lower and higher than this produced non-thermoelastic martensite. The 16 atomic % Sn samples were then subjected to pre straining. By straining the martensite phase, the shape memory behavior was proven by Thermomechanical Analysis (TMA) and was confirmed Differential Scanning Calorimetry (DSC). The following physical properties were then evaluated: (a) transformation temperatures, (b) mechanical properties, (c) metallurgical properties, and (d) thermomechanical properties. Transformation temperatures were all above 30 C, thus, Cu-Sn is a high-temperature SMA. Furthermore, temperature hysteresis, (As-Ms), was found to be very minimal (0.3 to 8 C) and within the maximum 50 C value typical to SMAs. This result further established that the developed alloy had shape memory behavior. To further investigate its behavior, the following mathematical models were developed: (a) transformation temperature as a function of austenitizing temperature and quenching rate, (b) Effects of austenitizing temperature and quenching rate on mechanical properties, and (c) stress recovery rate (one-way). To improve its ductility and workability the following grain refinement methods were designed and applied: (a) spin casting, and (b) direct rolling of the melt. Results showed improvement in ductility while maintaining and improving its shape memory behavior. Copper-tin alloys. Alloys Thermomechanical properties. Shape memory alloys. Shape memory effect. FI UP Thesis UPD DARCHIVES LG 996 2004 M37 A24 UPD DENG-II LG 996 2004 M37 A24 Thesis