热挤压处理对Mg-Gd-Y合金微观组织及腐蚀性能的影响

Effects of Hot Extrusion on Microstructure and Corrosion Properties of Mg-Gd-Y Alloy

为提高Mg-Gd-Y合金的耐蚀性能,通过对铸态镁合金进行热挤压处理,采用光学显微镜、扫描电子显微镜观察镁合金显微组织及腐蚀形貌,采用动电位极化曲线、交流阻抗和电化学噪声测试法研究铸态及挤压态Mg-Gd-Y合金在NaCl溶液中的电化学行为。研究结果表明:热挤压后Mg-Gd-Y合金内二次相弥散化、晶粒细化并沿挤压方向定向分布,腐蚀产物与合金基体结合紧密。自腐蚀电位正移,电化学噪声显示热挤压后Mg-Gd-Y合金局部腐蚀倾向和腐蚀程度减小。

The study aims to improve the anti-corrosive quality of Mg-Gd-Y alloys.The as-cast magnesium alloy was hot extruded first.The microstructure and corrosion morphology of the casting and extruded magnesium alloy were studied by using an OM and a SEM.The Electrochemical behavior of the as-cast and extruded magnesium alloys were studied by the methods of potentiodynamic polarization curve,alternating current impedance and electrochemical noise testing.The results show that the alloy’s second phase is of disperse distribution,grain refinement,and in orientation distribution after hot extrusion.The corroded product bounds tightly to the magnesium surface.The self-corrosion potential increases.And the electrochemical noise indicates that there is a decreasing tendency of local corrosion of Mg-Gd-Y alloy and its corrosion decreased after hot extrusion.