电弧熔丝增材制造Mg/Mg双金属的组织与力学性能  

Microstructure and Mechanical Properties of Mg/Mg Bimetals Fabricated by Wire Arc Additive Manufacturing

作　　者：韩启飞 狄兴隆 郭跃岭 叶水俊 郑元翾 刘长猛[1] HAN Qifei;DI Xinglong;GUO Yueling;YE Shuijun;ZHENG Yuanxuan;LIU Changmeng(School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]北京理工大学机械与车辆学院,北京100081

出　　处：《金属学报》2025年第2期211-225,共15页Acta Metallurgica Sinica

基　　金：国防基础科研计划项目,No.JCKY2023602B012。

摘　　要：传统工艺制备Mg/Mg双金属件流程复杂、成形效率低,电弧熔丝增材制造(WAAM)在提高大尺寸双金属件成形效率方面具有技术优势。为提高大尺寸Mg/Mg双金属件的成形效率和界面性能,本工作采用WAAM技术制备了Mg-Al-Si/Mg-Gd-Y-Zn双金属薄壁,研究了双金属件的宏观形貌、微观组织、显微硬度和力学性能。结果表明,该双金属件通过WAAM实现了良好的界面结合,双金属的界面为厚度约1.4 mm的过渡区。EPMA结果表明,过渡区内形成了成分梯度,从Mg-Al-Si合金侧到Mg-Gd-Y-Zn合金侧,Al和Si元素的含量逐渐降低,而Gd、Y和Zn元素的含量逐步增加。根据非平衡凝固相图和微观组织分析,双金属件由3个区域组成,分别是存在汉字状Mg_(2)Si相的Mg-Al-Si区,具有粒状Mg_(2)Si相、Mg_(3)(Gd,Y)相及Mg_(5)(Gd,Y)相的过渡区和以Mg_(12)Zn(Gd,Y)相为主的Mg-Gd-Y-Zn合金区。自Mg-Al-Si侧向Mg-Gd-Y-Zn侧,过渡区内的显微硬度从57 HV_(0.5)连续增加到90 HV_(0.5)。室温拉伸结果表明,双金属的强度接近Mg-Al-Si合金,极限抗拉强度和屈服强度分别为236.8和102.2 MPa,延伸率和加工硬化指数接近Mg-Gd-Y-Zn合金,分别为11.0%和0.323。WAAM Mg-Al-Si/Mg-Gd-Y-Zn双金属件的断裂位置位于过渡区,Mg-Al-Si合金的断裂机制以韧性断裂为主,而双金属和Mg-Gd-Y-Zn合金的断裂机理均为准解理断裂。Mg/Mg bimetallic components,especially Mg-Al-Si/Mg-Gd-Y-Zn bimetals,hold promise for applications in the aerospace and automotive industries as structural materials because of their potential advantages of low cost,lightweight,high strength,and high plasticity.At present,Mg/Mg bimetallic components are primarily fabricated via extrusion and compound casting.However,these conventional processes are complex and have low forming efficiency.Recently,rapid advancements in additive manufacturing have enabled the real-time manufacturing of bimetallic structural components.In particular,wire arc additive manufacturing(WAAM)offers technical advantages for improving the forming efficiency of large-sized bimetallic components.Herein,to enhance the forming efficiency and interfacial performance of large-sized Mg/Mg bimetallic components,a thin-walled Mg-Al-Si/Mg-Gd-Y-Zn bimetallic component was fabricated using WAAM technology.Specifically,a Mg-Al-Si alloy thin wall was first deposited and then cooled to room temperature over a period of time.Subsequently,the top layer of the Mg-Al-Si alloy thin wall was remelted,followed by the deposition of the Mg-Gd-Y-Zn alloy.Further,the macroscopic morphology,microstructure,microhardness,and mechanical properties of the bimetallic component were examined.Based on the macroscopic morphology,bimetallic components exhibited good interface bonding through WAAM.OM images demonstrated a transition zone near the bimetallic interface with a thickness of approximately 1.4 mm.The line scanning results and EPMA mappings revealed the formation of a composition gradient in the transition zone due to element diffusion.From the Mg-Al-Si alloy side to the Mg-Gd-Y-Zn alloy side,the Al and Si contents gradually decreased,while the Gd,Y,and Zn contents gradually increased.Based on the nonequilibrium solidification phase diagram and microstructure analysis,the bimetallic component comprised three regions:the Mg-Al-Si region with the Chinese-script Mg_(2Si)phase;transition region comprising granular Mg_2Si,

关 键 词：电弧熔丝增材制造 双金属件 组织 强化机理 

分 类 号：TG444[金属学及工艺—焊接]