Zn含量对热挤压Mg-8Al合金组织和力学性能的影响  

Effect of Zn Content on Microstructure and Mechanical Properties ofHot Extruded Mg-8Al Alloys

作　　者：张强 杨文朋[1,2] 陈亮 崔红保 ZHANG Qiang;YANG Wenpeng;CHEN Liang;CUI Hongbao(School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;Henan International Joint Research Laboratory for High-performance Light Metallic and Numerical Simulations,Jiaozuo 454000,China)

机构地区：[1]河南理工大学材料科学与工程学院,河南焦作454000 [2]河南省高性能轻金属材料及数值模拟国际联合实验室,河南焦作454000

出　　处：《有色金属工程》2023年第8期36-47,共12页Nonferrous Metals Engineering

基　　金：国家自然科学基金资助项目(51571086)。

摘　　要：制备Φ30 mm的Mg-8Al-xZn(x=0、2、4)合金铸锭,并在250~350℃将其挤压成Φ10 mm的棒材,利用光学显微镜(OM)、扫描电子显微镜(SEM)和透射电镜(TEM)分析合金组织,并测试合金拉伸性能。结果表明:铸态合金主要由α-Mg和β-Mg17Al12相组成,随着Zn含量增加,β相面积分数略有提升,层片状共晶β相形貌保持不变,而离异共晶β相由断续网状转变块状。250和300℃挤压时,组织因非连续动态再结晶而细化,随着Zn含量增加,组织中β相破碎程度增大,合金再结晶程度增加,未再结晶区域和孪晶减少,组织均匀性提高。然而,因硬脆β相增加,综合力学性能略有降低。350℃挤压时,组织发生完全动态再结晶,随着Zn含量增加,晶粒略微粗化,合金强度降低,延伸率显著提高。Mg-8Al-x Zn(x=0,2,4)alloy ingots with diameter of 30 mm were prepared,which were extruded into 0x0E䥺Symbol`@@0x0Fbars with diameter of 10 mm at a temperature range of 250 to 350℃.Microstructures were observed via Optical Microscope(OM),Scanning Electron Microscope(SEM)and Transmission Electron Microscopy(TEM),and the tensile properties were tested.The results show that as-cast alloys are mainly composed ofα-Mg andβ-Mg 17 Al 12 phases.With the increase of Zn content,the area fraction ofβphase increases slightly,the morphology of lamellar eutecticβphase is unchanged.However,divorced eutecticβphase was changed from discontinuous network to massive.After extrusion at 250℃and 300℃,the microstructures were refined due to the occurrence of discontinuous dynamic recrystallization.With the increase of Zn content,the extent of broken ofβphase and recrystallization of alloys are increased,the unrecrystallized area and twins decreased,and the homogeneity of the microstructure is improved.However,the comprehensive mechanical properties are decreased slightly due to the increase of brittleβphase.After extrusion at 350℃,complete dynamic recrystallization occurred.With the increase of Zn content,the grains are coarsened slightly and the alloys strength decreases and elongation increases obviously.

关 键 词：镁合金 Mg17Al12相 正挤压 再结晶 

分 类 号：TG146.2[一般工业技术—材料科学与工程]