Oxidation induced ductility enhancement of Zr based metallic glass ribbons in vicinity of glass transition temperature

Zr-based metallic glasses (MGs) possess a wide supercooled liquid region, which gives a wide processing window for superplastic forming to make microdevices with demanding size accuracy and surface finishing. The existence of oxygen may have an influence on the thermoplastic deformation process. Therefore, the effect of oxidation on the mechanical behavior of the MGs in the vicinity of glass transition temperature is of great significance for practical forming of MG components. In the present study, the effect of oxidation on tensile properties of Zr₅₀Cu₄₀Al₁₀ metallic glass was investigated. The tested samples were characterized by XRD and SEM analysis. For the samples tested in air, the strength decreases 187 MPa, 61 MPa and 59 MPa and the ductility increases 0.31, 0.36, and 0.77 at 420 ℃, 430 ℃, and 440 ℃, respectively, compared with those tested in flowing argon. ZrO₂ preferentially formed during the tensile testing at 420 ℃, and both ZrO₂ and Al₂O₃ oxides formed at 430 ℃. The dilution of Zr elements in the remaining amorphous matrix caused by preferential oxidation on the surface layer attributes to the decrease in strength and enhancement in ductility of the Zr₅₀Cu₄₀Al₁₀ metallic glasses.