| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 104 === In order to improve the mechanical properties as well as corrosion resistance of Mg-based metallic glass (BMG) and Mg-based metallic glass composite (BMGC). The Zr-based metallic glass thin film (MGTF) of 200 nm thickness was coated on the Mg-based BMGC with two different buffer layers, Al-Ti (25 nm/25 nm) and Cu(50 nm), for adhesion ability investigation. The BMGC plates (with dimension of 4 mm W x 3 mm T x 35 mm L) of Mg58Cu31Gd11 with 25 vol.% Mo particles (size of 25 m) [2] was selected as the substrate and coated with 200 nm Zr-based ((Zr53Cu30Ni9Al8)99.5Si0.5) MGTF by DC-sputtering. The results of 3-point bending test show that the flexural strength of the Mg-based BMGC (180 MPa) can be significantly enhanced to 254 MPa for the Mg-based BMGC with 200 nm Zr-based MGTF coating. The remarkable increase in flexural strength of the Mg-based BMGC coated with Zr-based MGTF is suggested that the Zr-based MGTF can smooth the surface (by covering the defects on the specimen surface) to prevent the stress concentration and also provide residual stress to suppress the crack initiation from the specimen surface during bending test. In addition, the results of polarization electrochemical test reveal that the Zr-based MGTF exhibits much better corrosion resistance in 0.9 wt. % sodium chloride solution. Accordingly, the coating of 200 nm Zr-based MGTF on the Mg-based BMGC by sputtering is believed a promising method to protect the Mg-based BMGC from the island environment.
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