高硬度Mg-5Al-2Sn-5Ca镁合金在铸态与热处理后的蠕变行为  

Investigation on Creep Behavior of Mg-5Al-2Sn-5Ca Magnesium Alloy withHigh Hardness in As-cast and After Heat-treatment

作　　者：热焱 邱克强[2] 李东和[1] 丁韧[1] 王梅 徐慧 徐颖 RE Yan;QIU Keqiang;LI Donghe;DING Ren;WANG Mei;XU Hui;XU Ying(Department of Mechanical and Electronic Engineering,College of Liaoning Provincial Communications,Shenyang 110122,China;School of Materials Science and Engineering,University of Technology Shenyang,Shenyang 110870,China)

机构地区：[1]辽宁省交通高等专科学校机电工程系,沈阳110122 [2]沈阳工业大学材料科学与工程学院,沈阳110870

出　　处：《材料导报》2020年第12期12076-12082,共7页Materials Reports

基　　金：辽宁省自然科学基金(20170540494)。

摘　　要：本工作借鉴MRI230D合金的设计思路,通过添加Al、Ca、Sn等元素,采用普通铸造工艺制备了一种新型的Mg-5Al-2Sn-5Ca镁合金。使用XRD衍射仪、扫描电子显微镜对样品进行表征,采用图像处理显微维氏硬度计和蠕变试验机测试合金在铸态与热处理后的力学性能。研究结果表明:该合金由α-Mg、Al 2Ca、Mg 2Ca、CaMgSn相组成;铸态及经热处理后(热处理态)的合金晶界处均分布着连续的骨架状相,具有较高的维氏硬度,且热处理态合金的晶粒内部有微小颗粒状相析出;在520℃,该合金才发生相变,说明合金具有较高的耐热性能。分别在50 MPa/200℃下对铸态合金和热处理态合金进行蠕变试验,结果发现,相比于铸态合金,经热处理后合金的总蠕变时间延长至540 h,蠕变总量降低了0.001%,但在100 h时的蠕变量减少了0.030%。对比其他研究者的蠕变数据可知,在相同条件下,该铸态合金的蠕变性能远优于MRI153镁合金;热处理后的合金在50 MPa/200℃的蠕变断裂时间也长于A380铝合金。In this work,a new Mg-5Al-2Sn-5Ca magnesium alloy was prepared by adding common elements such as Al,Ca and Sn by using the design ideas of MRI230D alloy.The composition of the alloy was determined by XRD,the microstructure and creep fracture of the alloy were observed by SEM,and the hardness of the alloy in as-cast and after heat-treatment was measured by image processing micro-Vickers hardness tester.The creep fracture time and creep elongation of the alloy in as-cast and after heat-treatment were measured by creep testing machine at 50 MPa/200℃.The XRD results showed that the alloy was composed ofα-Mg,Al 2Ca,Mg 2Ca,CaMgSn phase.It was observed by SEM that there were continuous skeleton phases at the grain boundary of the alloy in as-cast and after heat-treatment,and there were tiny particles precipitated in the grains after heat treatment.The alloy had higher Vickers hardness in as-cast and after heat-treatment,and the temperature of phase transformation was 520℃,which indicated that the alloy had high heat resistance.Creep tests were performed on as-cast and heat-treated alloys at 50 MPa/200℃,respectively.The results showed that compared to in as-cast alloys,the total creep time of the alloy after heat-treatment was extended to 540 h,and the total creep decreased 0.001%,but the creep variable at 100 h was reduced by 0.030%.Compared with the creep data of other researchers,under the same conditions,the creep properties of the as-cast alloy were much better than those of the MRI153 magnesium alloy;the creep fracture time of the alloy after heat treatment at 50 MPa/200℃was also longer than that of A380 aluminum alloy.

关 键 词：铸态 热处理 镁合金 骨架状相 显微维氏硬度 蠕变时间 

分 类 号：TG146.22[一般工业技术—材料科学与工程]