| Summary: | 碩士 === 義守大學 === 材料科學與工程學系碩士班 === 98 === The base alloy in this study is Mg58Cu29.5Y6Nd5Ag1.5 bulk metallic glass (BMG) rods were made by the injection casting method. The Ti particles (10、20 and 30vol.%) were selected to be the additive in the base material to form the bulk metallic glass composites (BMGCs). Ti powder was spherical with bimodal size in the range of 75~105μm and 45μm. The thermal stability and the microstructure characterizations of the resulting materials were performed by DSC、XRD and SEM. Vickers indentation and compression test were performed to estimate the mechanical properties of alloys.
The results indicated that GFA and thermal stability of Mg-based BMGCs decreased with increasing the content of Ti particles, but the glassy state of the matrix was maintained even in the coexistence with Ti powders. The fracture toughness and the ultimate strength of Mg-based BMGCs increased to 31MPa m1/2 and 963MPa, respectively. Besides, an improvement of compressive strain to ~7% of the Mg-based BMGCs with the addition of 30vol.% Ti particles. Moreover, SEM observations of Mg58Cu29.5Y6Nd5Ag1.5 with 30vol.% Ti powders showed that the propagation of shear bands could be stopped or branched by the dispersion of Ti particles with large size of 75~105μm and large sized vein patterns were formed upon the fracture surface. Although the small size Ti particles (45μm) could not stopped the shear bands motion, small size of vein patterns were formed in the interspacing of small Ti particles. The resulting Mg-based BMGCs with adding Ti particles in this study exhibit high glass forming ability (GFA) and excellent compressive properties.
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