| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 97 === This study utilized mechanical alloying and vacuum hot-pressing techniques to investigate the feasibility of obtaining a single phase of TiCoSn or TiNiSn alloy with half-Hesuler structure and measure their thermoelectric properties from initial compositions of TixCoySn100-x (x=20~60, y=20~60) and TixCoySn100-x (x=20~60, y=20~60) in Ti-Co-Sn and Ti-Ni-Sn system. For the Ti-Co-Sn system, it is found that the initial stoichimetric Ti1Co1Sn1 composition after milling can produce single half-Heusler TiCoSn phase and for those compositions that deviate from Ti1Co1Sn1 composition, milling can produce single amorphous, TiCo2Sn Heusler phase, TiCo2Sn, or TiCo2Sn and TiCo mixture, respectively. The milled Ti1Co1Sn1 powders were subjected to vacuum hot-pressing and vacuum hot-pressing plus subsequent densification treatment, respectively, to produce bulk materials with different density. The XRD results indicate that a single phase of bulk TiCoSn material can be produced by these processes. Thermoelectric measurements reveal the maximum power factors for the hot-pressed and hot-pressed plus densification bulk materials are 0.7897 μW/K2cm and 1.7455 μW/K2cm, respectively. For the Ti-Ni-Sn system, milling on the stoichiometric Ti1Ni1Sn1 composition can produce TiNiSn and TiNi compound mixture. Milling on the compositions in the neighborhood of Ti1Ni1Sn1 can produce a single phase of amorphous, Ni3Sn4, TiNi, or mixtures of TiNi2Sn+TiN, TiNiSn+TiNi, TiNiSn+TiNi+Ti, and Ni3Sn4+Ni. The power factor of the hot-pressed Ti1Ni1Sn1 bulk material is measured to be 0.3413 μW/K2cm.
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