Microstructure and Mechanical Properties of Extruded Mg-Zn-Y Alloy

Abstract:

A high strength and toughness extruded Mg-Zn-Y alloy based on quasicrystal-strengthening has been studied. The effect of extrusion and heat treatment on the microstructures and mechanical properties of Mg-Zn-Y alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and tensile testing. The experimental results indicated that the coarse dendrite crystals were broken through the hot extrusion, and dynamic recrystallization appeared during the hot extrusion, which obviously refined the hot-extruded microstructure to the average grain size about 20μm. A large amount of strengthening phases such as Mg₃Zn₆Y(I-Phase), Mg₁₂ZnY(X-Phase) and MgZn₂, which were massive, grainy and clavate, dispersedly precipitated from the matrix along grain boundary during ageing treatment at 225 after extrusion, and made the sliding of grain boundaries restrained, which resulted in an enhancement for mechanical properties to a great extent. At the same time, the tensile strength and yield strength increased after ageing treatment. After ageing treatment of 225×24h, the highest tensile strength and yield strength of the extruded Mg-Zn-Y alloy were obtained: σ_b=506.7MPa, σ_0.2=373.5MPa, which were increased by 104.8% and 120.4%, respectively, compared with the extruded Mg-Zn-Y alloy, however the elongation decreased to 16.52%.

• Periodical: Materials Science Forum (Volumes 747-748)
• Pages: 443-448
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.747-748.443
• Online since: February 2013
• Authors: Feng Wang, Ji Bao Li, Ping Li Mao, Zheng Liu
• Keywords: Extrusion, Heat Treatment, Mechanical Property, Mg-Zn-Y Alloy, Microstructure

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