稀土元素La对AlMgSi合金性能和微结构的影响  

Impacts of Rare Earth Element La on Properties and Microstructure of AlMgSi Alloys

作　　者：郑雄[1] 赖玉香 向雪梅 陈江华 ZHENG Xiong;LAI Yuxiang;XIANG Xuemei;CHEN Jianghua(College of Materials Science and Engineering,Hunan University,Changsha 410082,China;Pico Electron Microscopy Center,Center for Advanced Studies in Precision Instruments,Hainan University,Haikou 570228,China)

机构地区：[1]湖南大学材料科学与工程学院,长沙410082 [2]海南大学精密仪器高等研究中心皮米电镜中心,海口570228

出　　处：《金属学报》2024年第1期107-116,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.52001119;51831004和52171006。

摘　　要：微合金化是改善铝合金性能及微观结构的有效方法。本工作采用硬度、导电率和拉伸性能测试,以及SEM和TEM等表征分析手段,研究了不同含量La的添加对Al-0.75Mg-0.75Si(质量分数,%)合金性能和微观结构的影响。结果表明,随着La添加量的提高,(1)合金的塑性和导电率逐渐提高,这是由于La诱导形成的AlSiLa第二相的含量及其溶质原子Si消耗量逐渐增多;(2)合金的强度先上升后下降,强度的上升主要归因于AlSiLa相的强化作用及晶粒细化作用逐渐增大,强度的下降主要归因于固溶强化作用的减小;(3)合金人工时效过程中析出相的类型逐渐发生改变:加La合金峰值时效态除形成β″相外,还会析出多晶β″相,而过时效态会析出β″/U2、β′/U2和β′/U2/β″复合相。The 6xxx series aluminum alloys Al-Mg-Si(-Cu)are widely used in the automotive industry owing to their high strength-to-weight ratio,good formability,and corrosion resistance.Micro-alloying is an effective technique for enhancing the properties and microstructure of Al alloys.The effects of varying La additions on the microstructure and properties of Al-0.75Mg-0.75Si(mass fraction,%)alloy have been investigated using hardness,electrical conductivity,and tensile tests,as well as SEM and TEM.As the La content increases,the following observations are made:(1)the ductility and electrical conductivity of the alloy gradually increase due to the increase in the fraction of the AlSiLa secondary phases induced by the La addition and the amount of Si solute atoms consumed by these phases;(2)the strength of the alloy first increases due to the increase in the secondary-phase strengthening contribution of the AlSiLa phases and the grain refinement contribution,and then decreases owing to the decrease in the solid-solution strengthening contribution;and(3)the types of precipitates formed during aging gradually change;besides the β″phase,polycrystalline β″precipitates are also precipitated in the peak-aged alloys with La addition,while β″/U2,β′/U2,and β′/U2/β″composite precipitates are precipitated in the over-aging condition of the La-added alloys.

关 键 词：AL-MG-SI合金 微合金化 第二相 析出相 力学性能 电子显微镜 

分 类 号：TG113[金属学及工艺—物理冶金]