热挤压对铸态Mg-1Zn-0.3Zr-1Y-2Sn镁合金组织和性能的影响

Effect of Hot Extrusion on Microstructure and Properties of As-cast Mg-1Zn-0.3Zr-1Y-2Sn Magnesium Alloy

摘要:

通过光学显微镜（OM）、扫描电镜（SEM）、浸泡实验、析氢实验、电化学试验、拉伸试验等方法，研究了不同挤压温度（340、360、380、400 ℃）下，热挤压对铸态Mg-1Zn-0.3Zr-1Y-2Sn合金组织和性能的影响。结果表明：热挤压后，合金的第二相沿挤压方向破碎成颗粒，微观组织中存在动态再结晶和变形晶粒。随着挤压温度的升高，第二相的含量变化较小，动态再结晶晶粒尺寸逐渐增大。热挤压后，合金的力学性能得到改善，但其耐腐蚀性最终减弱。热挤压处理可以在腐蚀的早期阶段提高合金的耐腐蚀性能，但随着腐蚀的进行，在后期合金的耐蚀性能会降低。当热挤压温度为360 ℃时，合金具有较好的力学性能和耐腐蚀性能。

Abstract:

The effect of hot extrusion with different extrusion temperatures (340, 360, 380, and 400 °C) on the microstructure evolution and properties of the as-cast Mg-1Zn-0.3Zr-1Y-2Sn magnesium alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), immersion experiments, electrochemical experiment, and tensile test. The results show that after hot extrusion, the second phase of the alloy is broken into particles along the extrusion direction, while the grain size is significantly reduced, and dynamic recrystallization and deformation grains exist in the microstructure. As the extrusion temperature increases, the content of the second phase changes less, and the size of the dynamic recrystallization grain gradually increases. The mechanical properties of the extruded alloys are improved, but their corrosion resistance is weakened. The hot extrusion treatment can improve the corrosion resistance of the alloy in the early stage of corrosion, while as the corrosion proceeds, the corrosion resistance of the alloy in the later stage is weakened. When the hot extrusion temperature is 360 °C, the extruded alloy has relatively good mechanical properties and corrosion resistance.