(1. 华南理工大学 机械与汽车工程学院，广州 510640；
2. 华南理工大学 国家金属材料近净成形工程技术研究中心，广州 510640)
摘 要: 采用等通道转角挤压(ECAP)工艺在573 K温度下以Bc路径对双相合金Mg-10.73Li-4.49Al-0.52Y进行 1~6道次挤压变形，对变形合金进行显微组织观察、扫描电镜分析、X射线衍射测试和应变速率为1.5×10−3 s−1的室温拉伸实验。结果表明：该合金由(α+β)相组成，变形后晶粒沿着与挤压方向成30°~45°角且呈拉长的流线状，随挤压道次的增加，晶粒不断细化，其析出相Al2Y颗粒也随道次的增加沿晶粒拉长的方向均匀化和细化。合金原始铸态无织构，1道次变形后β相的主滑移面{110}晶面织构强度最高，变形3道次和6道次后该晶面织构强度相对1道次的下降，织构向周围移动。变形到3道次，室温下抗拉强度从铸态的137.5 MPa提高到最大值166.4 MPa；4道次后，强度有一定程度下降。断口分析表明，经6道次变形后断口呈典型的延性断裂特征，存在更多的韧窝，并获得较大的室温伸长率(83%)。
关键字: 镁锂合金；等通道转角挤压；显微组织；力学性能；织构
（1. School of Mechanical and Automotive Engineering, South China University of Technology,
Guangzhou 510640, China;
2. National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China）
Abstract:The microstructure evolution and mechanical properties of Mg-10.73Li-4.49Al-0.52Y two-phase magnesium alloy processed by equal channel angular pressing (ECAP) from 1 pass to 6 passes at 573 K using route Bc were analyzed by OM, SEM and XRD, and the mechanical properties were tested at room temperature with strain rate of 1.5×10−3 s−1. The results indicate that the magnesium alloy grains consist of α phase and β phase which are elongated to be streamline at an angle of 30°−45° to the extrusion direction after ECAP, and the initial large and disperse phases of Al2Y are refined and homogenized as the extrusion pass increases. After 1 pass, non-oriented texture of the as-cast alloy exhibits the strongest texture on the main crystal {110} of β phase; after 3 and 6 passes, the texture intensity declines compared with that of 1 pass deformation, and their texture moves to periphery. After 3 passes, the tensile strength increases to the maximum of 166.4 MPa from 137.5 MPa of the as-cast at room temperature. After 4 passes, the tensile strength decreases a little. The fracture surfaces show that the fracture mode of the 6-pass ECAPed alloy shows typical ductile fracture and more dimples, and its elongation is up to 83%.
Key words: Mg-Li alloy; equal channel angular pressing (ECAP); microstructure; mechanical property; texture
