(陕西理工学院 材料科学与工程学院，汉中 723003)
摘 要: 研究往复挤压对Mg-4Al-4Si (AS44)合金显微组织和性能的影响。结果表明：往复挤压显著地细化晶粒，改善组织的均匀性；往复挤压4道次和8道次后，Mg2Si颗粒尺寸由铸态下的约 120 µm分别减小至3和2 µm，α-Mg基体晶粒尺寸由铸态下的约50 µm分别减小至9和8 µm，形成了较为细小、弥散分布的Mg2Si颗粒和细小的等轴晶组织。合金的力学性能随往复挤压道次的增加而显著提高，挤压8道次时，合金的极限抗拉强度、屈服强度和伸长率分别达到251.7 MPa、210.5 MPa和14.8%，与铸态合金相比，上述力学性能指标分别提高了131.3%、191.1%和469.2%；挤压态合金拉伸断裂形式为微孔聚合型韧性断裂。
关键字: Mg-4Al-4Si镁合金；往复挤压；组织细化；力学性能
（School of Materials Science and Engineering, Shanxi University of Technology, Hanzhong 723003, China）
Abstract:Effects of reciprocating extrusion (RE) on microstructures and mechanical properties of Mg-4Al-4Si (AS44) alloy were investigated. The results show that the microstructures of the alloy are refined and uniformed obviously by RE. After RE for 4 passes and 8 passes, the as-cast Mg2Si particle sizes decrease from about 120 µm to 3 and 2 µm, respectively, the as-cast α-Mg grain sizes decrease from about 50 µm to 9 and 8 µm, respectively. The fine equiaxed grains are formed with homogeneous distribution of fine Mg2Si particles. The mechanical properties of alloy are improved obviously with increasing the RE passes. After RE 8 passes, the ultimate tensile strength, yield strength and elongation of alloy reach 251.7 MPa, 210.5 MPa and 14.8%, respectively. The previous mechanical data are increased by 131.3%, 191.1% and 469.2% compared with as-cast AS44, respectively. The fracture forms of RE alloy are ductile rupture.
Key words: Mg-4Al-4Si magnesium alloy; reciprocating extrusion; microstructure refine; mechanical property
