消失模铸造AZ91镁合金组织及耐蚀性研究  

Study on Structure and Corrosion Resistance of AZ91 Magnesium Alloy in Lost Foam Casting Process

作　　者：吴国华[1] 刘子利[2] 樊昱[1] 丁文江[1] 朱燕萍[1] 

机构地区：[1]上海交通大学金属基复合材料国家重点实验室,上海200030 [2]南京航空航天大学,江苏南京210016

出　　处：《铸造》2005年第8期767-771,共5页Foundry

基　　金：国家自然科学基金资助项目(50474005);国家863计划资助项目(2002HA331120)。

摘　　要：通过采用金相分析、能谱分析、电子万能材料试验机、腐蚀失重法、极化测试及交流阻抗分析等手段,研究了消失模铸造AZ91镁合金的组织、力学性能及腐蚀行为,并与普通砂型铸造及金属型铸造方法进行了比较。研究结果表明,消失模铸造镁合金组织除了粗大的α相与β相外,还出现了球状的Al-Mn-Fe三元相,造成消失铸造镁合金的力学性能及耐蚀性能低于砂型铸造及金属型铸造。本试验条件下,消失模铸造AZ91合金的抗拉强度及伸长率分别为135.6MPa与1.4%。失重法测得的消失模铸造AZ91镁合金的腐蚀速率为0.64mg/(cm2·d),为金属型铸造的2.2倍。极化曲线及交流阻抗等电化学研究表明,铸造工艺对镁合金的腐蚀行为有明显影响,消失模铸造镁合金的自腐蚀电位较低,但自腐蚀电流密度较大,分别为-1.577V与1.39×10-5Amp/cm2。The microstructure, mechanical properties and corrosion behavior of AZ91 Mg alloy in lost foam casting （LFC） have been studied by metallographic microscope, EDX, electronic universal materials testing machine, weight loss corrosion rate, potentiodynamic polarization and impedance spectroscopy measurements, and were compared with these of ordinary sand mould casting and permanent mould casting. The results show that except for the coarse α and β phases, the ternary Al-Mn-Fe phase also appeared in the microstructure in LFC casting. The lower mechanical properties and corrosion resistance of LFC AZ91 compared with these of ordinary sand mould casting and permanent mould casting were obtained. The experimental results show that the tensile strength and elongation of LFC AZ91 alloy are 135.6 MPa and 1.4% respectively, and its weight loss corrosion rate is 0.64 mg/ （cm^2·d） , 2.2 times that of the permanent mould casting. The research results of potentiodynamic polarization and impedance spectroscopy measurement show that the casting processes have obvious effect on the corrosion behavior of magnesium alloy, and the LFC AZ91 alloy has lower corrosion potential and higher corrosion current density, their values are -1.577 V and 1.39×10^ -5 Amp/cm^2, respectively.

关 键 词：镁合金 组织 消失模铸造 腐蚀 

分 类 号：TG249.5[机械工程—精密仪器及机械]