Mg-Al合金非平衡凝固共晶组织及形成机理  

Eutectic structure and its formation mechanism in non-equilibrium solidified Mg-Al alloys

作　　者：孙晶[1] 郭全英[1] 毛萍莉[1] 刘正[1] 

机构地区：[1]沈阳工业大学材料科学与工程学院,沈阳110870

出　　处：《沈阳工业大学学报》2013年第6期635-640,共6页Journal of Shenyang University of Technology

基　　金：国家科技支撑计划资助项目(2011BAE22B06)

摘　　要：为了研究Mg-Al合金非平衡凝固组织,利用扫描电镜(SEM)、x-射线衍射仪以及拉伸性能测试,分析了金属型铸造Mg-x%Al(x=8、10、12)合金的铸态组织.结果表明,Mg-x%Al(x=8、10、12)合金的铸态组织由α固溶体、沿晶界分布共晶组织及其附近的次生相所组成,共晶组织以β-Mg17Al12为基且其上分布着粒状α相,次生β相与α固溶体以片层相间的形式出现.采用金属型铸造,实验合金的冷却速度较快,先形成离异共晶的β-Mg17Al12相,后形成以β-Mg17Al12为基的共晶组织.该组织为类似于铁碳合金中莱氏体的非规则共晶体,强度和塑性很低,因此,Mg-x%Al(x=8、10、12)合金的力学性能普遍较低.Abstract： In order to study the non-equilibrium solidified microstructure of Mg-Al alloy, the microstructure of permanent mold casting Mg-x% Al （x = 8, 10, 12 ） alloys was analyzed with scanning electron microscope （SEM） and x-ray diffractometer （XRD）. In addition, the tensile properties of the alloys were tested. The results show that the microstructure of as-cast Mg-x% Al （x = 8, 10, 12）alloys is composed of α solid solution, eutectic structure along the grain boundary, and secondary phase near the eutectic structure. The matrix of eutectic structure is α-Mg17Al12 phase and some granular α phase distributes on the β-Mg17Al12 phase. The secondary β phase alternates with tx solid solution in a lamellar morphology. With the permanent mold casting method, the cooling rate for the experimental alloy is faster, the β-MglTAl12 phase with the divorced eutectic feature firstly forms, and then the β-Mg17Al12 phase based eutectic structure forms. Such eutectic structure is an irregular eutecticum similar to the ledeburite in Fe-C alloy, and exhibits low strength and plasticity. Therefore, the mechanical properties of as-cast Mg-x% Al （x = 8, 10, 12 ） alloys are generally lower.

关 键 词：MG-AL合金 非平衡凝固 共晶组织 镁合金 力学性能 β-Al12Mg17 相 次生相 化合物 

分 类 号：TG146.2[一般工业技术—材料科学与工程]