后时效对超细晶6061铝合金微观结构与力学性能的影响  

Effect of Post-Aging on Microstructure and Mechanical Properties of an Ultrafine-Grained 6061 Aluminum Alloy

作　　者：刘满平[1,2] 薛周磊 彭振 陈昱林[1] 丁立鹏 贾志宏 LIU Manping;XUE Zhoulei;PENG Zhen;CHEN Yulin;DING Lipeng;JIA Zhihong(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212013,China;State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China;Key Laboratory for Light-Weight Materials,Nanjing Tech University,Nanjing 211816,China;School of Materials Science and Engineering,Chongqing University,Chongqing 400030,China)

机构地区：[1]江苏大学材料科学与工程学院,镇江212013 [2]湖南大学汽车车身先进设计制造国家重点实验室,长沙410082 [3]南京工业大学先进轻质高性能材料研究中心,南京211816 [4]重庆大学材料科学与工程学院,重庆400030

出　　处：《金属学报》2023年第5期657-667,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.U1710124;51871035和52001159;湖南大学汽车车身先进设计制造国家重点实验室开放基金项目No.32115014。

摘　　要：采用TEM、XRD、显微硬度实验和拉伸实验,利用等通道转角挤压(ECAP)和后时效相结合制备出超细晶6061铝合金,对其微观结构和力学性能进行了对比研究。结果表明,经过两道次ECAP后,合金的平均晶粒尺寸细化到210 nm。两道次ECAP+80℃、20 min低温后时效,合金的平均晶粒尺寸为278 nm,基体中弥散分布细小的针状β’’、L相和Q’相纳米级析出物,拉伸强度和屈服强度分别达到514和483 MPa,并保持了15.1%的均匀伸长率。ECAP在基体中引入的大量位错促进了析出相的形核,加速了时效过程中的析出动力学;ECAP低温后时效,合金的高强度和高韧性与细晶强化、位错强化和纳米析出相强化有关。基于实验结果,分析了合金ECAP和后时效过程中时效相的演变过程。Al-Mg-Si alloys are widely used in automotive body panels and parts of the engine owing to their low density,medium strength,high specific strength,good corrosion resistance and other characteristics.Currently,there are many studies on the precipitation behavior of undeformed Al-Mg-Si aluminum alloy,but there is a lack of research on the precipitation evolution and precipitation strengthening mechanism of ultra-fine grained 6061 aluminum alloy at different post-aging temperatures.In this study,the microstructure and mechanical properties of an ultrafine grain 6061 aluminum alloy produced by combining the equal channel angular pressing(ECAP)and post aging methods was comparatively evaluated via TEM,XRD,microhardness tests,and tensile tests.The results indicated that the average grain size of the alloy after two ECAP passes was refined to 210 nm.The average grain size of the alloy after the ECAP pass at 80oC and 20 min post aging was 278 nm;moreover,the fine needleβ'',L phase,and Q'phase precipitates at nanoscale were dispersed in the matrix.Furthermore,the tensile and yield strengths were 514 and 483 MPa,respectively,while maintaining a remarkably uniform elongation of 15.1%.These results indicate that numerous dislocations introduced by ECAP in the matrix provide a location for the nucleation of the precipitate,which accelerates the precipitation kinetics during the post aging process.The high strength and toughness of the ECAP alloy after low temperature post aging can be attributed to the grain refinement strengthening,dislocation strengthening,and nanoprecipitation strengthening.Thus,the evolution of the aging precipitates during the ECAP and post aging alloy was analyzed.

关 键 词：AL-MG-SI-CU合金 超细晶 低温后时效 微观结构 力学性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]