激光粉末床熔融稀土改性高强铝合金形性调控研究  

Performance and Structure Control of Rare⁃Earth⁃Element Modified High⁃Strength Aluminum Alloy Processed by Laser Powder Bed Fusion

作　　者：齐世文 顾冬冬[1,2] 张晗 戴冬华 Qi Shiwen;Gu Dongdong;Zhang Han;Dai Donghua(College of Materials Science and Technology,Nanjing University of Aeronautics&Astronautics,Nanjing 210016,Jiangsu,China;Jiangsu Provincial Engineering Research Center for Laser Additive Manufacturing of HighPerformance Components,Nanjing 210016,Jiangsu,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210016 [2]江苏省高性能构件激光增材制造工程研究中心,江苏南京210016

出　　处：《中国激光》2024年第10期244-254,共11页Chinese Journal of Lasers

基　　金：装备预先研究领域基金项目(JZX7Y20210263400301);江苏省重点研发计划(产业前瞻与关键核心技术)(BE2022069,BE2022069-1);民用航天预研项目(D020302)

摘　　要：激光增材制造稀土改性高强铝合金因具备轻质高强、复杂构件一体化成形等优势,在航空航天领域具有广阔的应用前景。围绕激光增材制造成形工艺优化、冶金缺陷抑制、力学性能提升及复杂构件形性调控等的研究是近年来的研究难点。本团队开展了激光粉末床熔融成形稀土改性高强铝合金Al-4.2Mg-0.4Sc-0.2Zr的激光工艺优化研究,基于试验表征与数值模拟相结合的方法,揭示了激光扫描速度对成形试件表面质量、内部冶金缺陷、熔池传热传质行为及纳米析出相分布的影响机制。结果显示:当激光功率为300 W、激光扫描速度为800 mm/s,并辅以325℃/4 h的时效热处理时,成形试件的致密度最优,为99.5%,抗拉强度为512.4 MPa,延伸率为13.3%。基于优化工艺参数对航空领域两类典型的复杂构件开展了成形试验研究,成形试件的最长外形尺寸为570 mm,表面粗糙度Ra≤7.3μm,尺寸精度可达0.1 mm/100 mm。Objective The integrated laser powder bed fusion(LPBF)forming of complex components of lightweight and highstrength aluminum alloys provides a new impetus for the development of lightweighting in the aerospace field.However,the control of the forming quality and performance of LPBFfabricated highstrength aluminum alloys components and their applications still face bottleneck problems.On the one hand,the strengthening mechanism of AlSi alloys is relatively simple,and the tensile strength of LPBFfabricated AlSi alloys is usually lower than 400 MPa,which hardly meets the highperformance requirements in the aerospace field.On the other hand,AlCu 2xxx alloys and AlZn 7xxx alloys,which are often used in conventional processing,can be heattreated to achieve a large number of diffusely distributed nanoprecipitated phases,providing an effective diffusion strengthening effect and realizing excellent mechanical properties in excess of 500 MPa.However,LPBF is a nonequilibrium melting process with cooling rates of up to 105‒107 K/s owing to the transient interaction of the highenergy laser beam with the metal powder.Due to the wide solidification interval of 2xxx and 7xxx aluminum alloys,the solidliquid coexistence time is long,and it is difficult to fill the liquid phase in time during the laser fast melting and solidification process.This easily results in solidification cracks along the grain boundaries,which greatly limits the application and development of LPBF forming with highstrength aluminum alloys.In this work,we achieved a densification of 99.5%,a tensile strength of 512.4 MPa,and an elongation of 13.3%for the specimens by optimizing the laser process parameters for LPBF forming of AlMg alloys modified with rareearth elements,namely,Sc and traces of Zr.The research results can provide a reference for the integrated LPBF molding of aerospace lightweight components.Methods Atomized prepared Al4.2Mg0.4Sc0.2Zr alloy powder was used for LPBF process.First,the samples were manufactured using scanning speeds of 400,800,

关 键 词：激光技术 增材制造 激光粉末床熔融 高强铝合金 工艺调控 力学性能 

分 类 号：TH164[机械工程—机械制造及自动化]