往复挤压Mg-4Al-4Si镁合金的显微组织与力学性能

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120μm分别减小至3和2μm,α-Mg基体晶粒尺寸由铸态下的约50μm分别减小至9和8μm,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。

Microstructures and mechanical properties of Mg-4Al-4Si magnesium alloy by reciprocating extrusion

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.