Mg/Si含量比值对Al-Mg-Si合金析出行为的影响  

A comparison study of precipitation behaviors in three Al-Mg-Si alloys with different Mg/Si composition ratios

作　　者：桑益[1] 陈江华[1] 刘春辉[1] 王时豪[1] 黄昌军[1] 

机构地区：[1]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《电子显微学报》2012年第5期384-390,共7页Journal of Chinese Electron Microscopy Society

基　　金：国家重点基础研究发展计划资助项目(No.2009CB623704);国家自然科学基金资助项目(No.51171063);湖南省高校科技创新团队项目;湖南省研究生科研创新项目;Gatan中国博士生奖学金

摘　　要：采用显微硬度计、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)及能谱仪,研究了不同Mg/Si含量比的Al-Mg-Si合金在不同时效温度下的时效析出行为。合金为Mg含量相同,Mg/Si摩尔比接近2.0、1.0和0.5的三种A、B和C合金(合金总含量依次增多)。结果表明:Mg/Si含量比对析出动力学有很大影响,温度越高Mg/Si摩尔比对时效动力学影响越大。SEM分析表明:Si含量越高的合金,晶界析出相越连续且尺寸越大,并有一定的晶界无析出带。HRTEM分析表明:过时效阶段,β'相的形成跟Mg/Si比和温度有关;两种时效温度下,在A合金中均析出β'相;而B和C合金在180℃时效主要析出β″相,250℃时效时,B合金中易形成TypeB相,C合金可析出TypeA、TypeB和TypeC三种相。The precipitation behaviors of there Al-Mg-Si alloys with different Mg/Si composition ratios were studied in this paper.The mechanical property and the precipitate microstructures were characterized by Vickers micro-hardness tester,Scanning electron microscopy（SEM）,and High-resolution transmission electron microscopy（HRTEM）.It was found that the Mg/Si composition ratio has a profound effect on the precipitation kinetics and the effect becomes lager at higher aging temperature.SEM observations indicated that grain boundary precipitates rich in Si become denser and larger when more Si atoms were added in the alloy.The precipitate free zones along the grain boundary were observed.HRTEM observations reveal that the formation of β′-phase in the over-aged samples is related with the Mg/Si composition ratio.The β″-phase precipitates mostly formed in alloys with a Mg/Si composition ratio below 1.0 when aged at 180 ℃.When aged at 250 ℃,Type B phase was observed to form in the alloy with the Mg/Si composition ratio of about 1.0.However,three types of precipitates were found in the alloy with a Mg/Si composition ratio of about 0.5 when aged at 250 ℃.

关 键 词：铝合金 析出相 时效 微观结构 透射电镜 

分 类 号：TG146.2[一般工业技术—材料科学与工程] TG111.5[金属学及工艺—金属材料]