Gd对Mg-xGd-0.8Mn镁合金组织和耐蚀性能的影响  

Microstructure and Corrosion Resistance of Mg-xGd-0.8Mn Magnesium Alloy by Gd Addition

作　　者：聂中奎 古东懂 杨宗全 高攀 陶健全[3] 彭建[1] Nie Zhongkui;Gu Dongdong;Yang Zongquan;Gao Pan;Tao Jianquan;Peng Jian(State Key Laboratory of Mechanical Transmission,College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Jiaozuo Gaozhao Magnesium Alloy Co.Ltd.,Jiaozuo 454950,China;Southwest Technique and Engineering Institute,Chongqing 400039,China)

机构地区：[1]重庆大学材料科学与工程学院机械传动国家重点实验室,重庆400044 [2]焦作市高招镁合金有限公司,河南焦作454950 [3]西南技术工程研究所,重庆400039

出　　处：《稀有金属》2024年第4期457-466,共10页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(U2241231);国家重点研发计划项目(2021YFB3701100)资助。

摘　　要：采用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、电子背散射衍射(EBSD)、腐蚀测试等手段研究了稀土元素Gd对Mg-xGd-0.8Mn(x=0,2,4,6;%,质量分数)合金组织和耐蚀性能的影响。结果表明:Gd对挤压态合金有较强的晶粒细化效果,同时可以有效弱化合金的基面织构。随着Gd含量的增加,挤压态Mg-xGd-0.8Mn合金的第二相体积分数不断增加,而第二相平均尺寸则是先减小后增加并趋于恒定。挤压态Mg-xGd-0.8Mn合金的耐腐蚀性能主要取决于晶粒尺寸和第二相尺寸。Gd添加引起的组织细化,促使合金耐腐蚀性能显著增强。然而,当Gd含量为4%时,合金第二相粗大且分布不均匀,导致了剧烈的局部腐蚀,弱化了合金的耐腐蚀性能。当Gd含量为6%时,合金晶粒尺寸最细小,第二相体积分数明显增加,形成了相对均匀致密的腐蚀产物层而继续改善合金的耐腐蚀性能,其中合金腐蚀失重速率和腐蚀析氢速率分别为(1.79±0.26)mg·cm^(-2)·d^(-1)和(1.39±0.18)ml·cm^(-2)·d^(-1)。基于添加Gd的合金化成本及耐蚀性能提升效果考虑,Mg-2Gd-0.8Mn合金应用前景更好。Magnesium alloy has a series of advantages such as light weight,high specific stiffness,high casting productivity,and easy recycling,making it especially suitable for transportation,national defense and military industry,3C products,and many other fields.However,the corrosion resistance of magnesium alloy is relatively poor due to the low standard electrochemical potential,poor metallurgical quality,unstable hydrogen oxide film formed on the surface and easy to form galvanic couple with the second phase,which will seriously limit its application.Therefore,improving the corrosion resistance of magnesium alloy has become an urgent problem in the research and engineering application of high performance magnesium alloy.Generally,proper addition of alloying elements(such as Gd element)can not only effectively remove Fe impurities in the alloy and improve its purity,but also improve the structure and properties of the alloy.In fact,the content of rare earth elements in most high-performance Mg-Gd alloys is relatively high(mass fraction≥10%),which greatly increases the manufacturing cost of Mg-Gd alloys,and seriously weakens the effect of weight reduction and lightweight.Thus,it is of great significance to develop and design high-performance Mg-Gd alloys on the premise of reducing Gd addition.The effect of the rare earth element Gd on the microstructure and corrosion resistance of Mg-x Gd-0.8Mn(x=0,2,4,6;%,mass fraction)alloy was studied,and the corrosion mechanism of the extruded Mg-x Gd-0.8Mn alloy was explained in this paper.The alloy ingots were prepared from high-purity Mg(99.99%),Mg-25Gd(%,mass fraction)master alloy and Mg-3.25Mn(%,mass fraction)master alloy by fabricating in a low carbon steel crucible under a mixed protective gas consisting of SF_(6) and CO_(2)(volume ratio=1∶100).After stirring at 760℃for 5 min,the melt was keeping at 720℃for 30 min,then quenched the crucible into cold water to get a solidified bar.The actual chemical compositions of Mg-x Gd-0.8Mn alloy were determined by inductively-co

关 键 词：镁合金 GD 晶粒细化 第二相 耐蚀性能 

分 类 号：TG174.1[金属学及工艺—金属表面处理]