| Summary: | 碩士 === 中華大學 === 機械與航太工程研究所 === 95 === Recently, industries are seeking light metals which could be recycled because of energy shortage and the environmental protection. Magnesium alloy is an attractive structural metal for industries due to the property of recycling. At present, use of Mg alloys has been developed for electronic appliances, bike and motor vehicle components. Alloying Mg with lithium yields a lightest structural metal of Mg-Li alloy. However, the mechanical properties of Mg-Li alloy are not particularly favorable for structural applications due to its low tensile and yield strength. For this reason, the purpose of this study explore the effect of minor addition of scandium (Sc), aluminum (Al), and zinc (Zn) on the properties of the Mg-Li alloy, and the major consideration focus on the influence of adding Sc. Rolling and age heat treatment were performed to investigate the variations in microstructures and tensile behaviors. As the result, Widmanstatten structure was found in the alloy with Sc addition. The alloys with or with out Sc addition presented no age hardenable effect; but the grain size would increase with aging temperature. Work hardening were observed for both alloys with and without Sc addition. The highest hardness appeared as the reduction was up to about 60%. This result revealed that suitable thermo-mechanical treatment could be used to improve the mechanical properties of the LAZ alloys.
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