(1. 内蒙古科技大学 材料与冶金学院，包头 014010；
2. 重庆大学 材料科学与工程学院，重庆 400044；
3. 内蒙古第一机械集团有限公司 第十分公司，包头 014030；
4. 重庆大学 国家镁合金工程技术研究中心，重庆 400044)
摘 要: 通过OM、SEM、XRD和拉伸实验研究3种典型的Mg-Li-Al合金的铸态和挤压态组织及力学性能。结果表明：随着Li含量的增加，合金的结构从密排六方向体心立方转变，合金的铸态组织随之发生改变。经过250 ℃挤压处理后，Mg-5Li-1Al和Mg-9Li-1Al合金的晶粒沿挤压方向呈方向性排列，Mg-14Li-1Al合金由均匀的等轴晶(再结晶晶粒)组成。随着Li含量的增加，挤压态合金板材的屈服强度逐渐增大，其中挤压态Mg-9Li-1Al合金板材的综合力学性能最佳(屈服强度达到149 MPa，伸长率达到25%)。
关键字: 镁锂合金；挤压；显微组织；力学性能
（1. School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China;
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
3. The Tenth Sub-company, Inner Mongolia First Machinery Group Corporation, Baotou 014030, China;
4 National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China）
Abstract:The as-cast and extruded microstructures and mechanical properties of three kinds of Mg-Li-Al alloys were studied by optical microscopy, SEM, XRD and tensile test. The results show that, with the increase of lithium additions, the crystal structure transforms from close-packed hexagonal (HCP) structure to body centered cubic (BCC) structure, and the as-cast microstructures of the Mg-Li-Al alloys change correspondingly. After extrusion at 250℃, the grain of Mg-5Li-1Al and Mg-9Li-1Al alloys are arranged along the extruded direction, but the microstructures of Mg-14Li-1Al alloy sheet consist of equiaxed crystals. The yield stress of the extruded alloys is improved gradually with the increase of lithium content. The extruded Mg-9Li-1Al alloy obtains the optimal mechanical properties (the yield stress and elongation are 149 MPa and 25%, respectively), along the transverse direction.
Key words: Mg-Li alloy; extrusion; microstructure; mechanical property
