| Summary: | 碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 105 === There is a very long history of the development of titanium alloy, and the two main reasons for developing titanium alloy are low manufacturing cost and its excellent mechanical properties. Although the manufacturing cost can be lower through powder metallurgy, the relative density and strength will also be lower than the titanium alloy manufactured by other methods. However, adding nickel and molybdenum can improve the mechanical properties and lower the porosity of titanium alloy while maintaining the low cost. In this experiment, we adjust the weight percent of Ti, Ni and Mo powder of Ti-xNi-6Mo (x:1~9) and analyze the microstructure and the mechanical properties of the Ti-Ni-Mo alloy prepared by powder metallurgy and vacuum sintering.
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The results show that after vacuum sintering at 1200°C, Ti-9Ni-6Mo alloy has higher Rockwell hardness (67.15 HRA) and corrosion resistance (18896 Ω/cm2) among all but the formation of brittle Ti-Ni intermetallic compound with large grain size will let the transverse rupture strength drop sharply. However, Ti-4Ni-6Mo alloy has highest transverse rupture strength (1116.8 MPa) because the structure is strengthened by α phase precipitating in the grain, and fracture surface has the feature of dimple fracture.
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