(陜西理工學(xué)院 材料科學(xué)與工程學(xué)院，漢中 723003)
摘 要: 研究往復(fù)擠壓對Mg-4Al-4Si (AS44)合金顯微組織和性能的影響。結(jié)果表明：往復(fù)擠壓顯著地細化晶粒，改善組織的均勻性；往復(fù)擠壓4道次和8道次后，Mg2Si顆粒尺寸由鑄態(tài)下的約 120 µm分別減小至3和2 µm，α-Mg基體晶粒尺寸由鑄態(tài)下的約50 µm分別減小至9和8 µm，形成了較為細小、彌散分布的Mg2Si顆粒和細小的等軸晶組織。合金的力學(xué)性能隨往復(fù)擠壓道次的增加而顯著提高，擠壓8道次時，合金的極限抗拉強度、屈服強度和伸長率分別達到251.7 MPa、210.5 MPa和14.8%，與鑄態(tài)合金相比，上述力學(xué)性能指標分別提高了131.3%、191.1%和469.2%；擠壓態(tài)合金拉伸斷裂形式為微孔聚合型韌性斷裂。
關(guān)鍵字: Mg-4Al-4Si鎂合金；往復(fù)擠壓；組織細化；力學(xué)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
