Microstructure and Properties of As-Cast Mg-2.0Sn-1.0Zn-1.0Y-0.3Zr Alloys at Different Extrusion Ratios

Herein, the effect of hot extrusion with different extrusion ratios (lambda = 6, 8, 10, and 12) on the microstructure evolution and properties of as-cast Mg-2.0Sn-1.0Zn-1.0Y-0.3Zr magnesium alloys, using optical microscopy (OM), scanning electron microscopy (SEM), immersion corrosion and electrochemical corrosion experiment, and tensile testing, is investigated. The results show that the Mg14SnY and Mg6SnY precipitated phases exist in the alloy before and after extrusion. After hot extrusion, the second phase of the alloy is broken into particles along the extrusion direction, whereas the grain size is significantly reduced, and dynamic recrystallization and deformed grains exist in the microstructure. The mechanical properties of the extruded alloy improve, but the corrosion resistance weakens. When the extrusion ratio is lambda = 10, the extruded alloy exhibits relatively good mechanical properties and corrosion resistance. The corrosion behaviors of the extruded alloys are affected by both the grain size and galvanic corrosion. In the initial stage of corrosion, intergranular corrosion plays a major role in reducing the corrosion resistance of the extruded alloys. With prolonged corrosion time, galvanic corrosion has a more significant effect on weakening the corrosion resistance of the extruded alloys.

Automated summary

This study investigates the microstructure evolution and properties of as-cast Mg-2.0Sn-1.0Zn-1.0Y-0.3Zr magnesium alloys under different extrusion ratios (lambda = 6, 8, 10, and 12) using various techniques. The results show that the alloy consists of Mg14SnY and Mg6SnY precipitated phases before and after extrusion. Hot extrusion leads to the breaking of the second phase into particles and a significant reduction in grain size, along with the presence of dynamic recrystallization and deformed grains in the microstructure. The mechanical properties of the extruded alloy improve, but its corrosion resistance weakens. The alloy extruded with a ratio of lambda = 10 exhibits relatively good mechanical properties and corrosion resistance. The corrosion behaviors of the extruded alloys are influenced by grain size and galvanic corrosion.