Effect of bonding temperature and heat treatment on microstructure and mechanical property of Mg−6Gd−3Y alloy vacuum diffusion bonded joints  

焊接温度和热处理对Mg-6Gd-3Y合金真空扩散焊接头显微组织和力学性能的影响

作　　者：Ping-yi MA Xu CHEN Xing HAN Zhi-qiang LUO He-li PENG 马平义;陈旭;韩兴;罗志强;彭赫力(上海航天精密机械研究所,上海201600;上海金属材料近净成形工程技术研究中心,上海201600)

机构地区：[1]Shanghai Spaceflight Precision Machinery Institute,Shanghai 201600,China [2]Shanghai Engineering Technology Research Center of Near-Net Shape Forming for Metallic Materials,Shanghai 201600,China

出　　处：《Transactions of Nonferrous Metals Society of China》2022年第7期2205-2215,共11页中国有色金属学报（英文版）

基　　金：financially supported by the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology,China (No.SAST2020-117)。

摘　　要：Diffusion bonding of as-cast Mg−6Gd−3Y magnesium alloy was carried out at temperatures of 400−480℃ with bonding pressure of 6 MPa for 90 min.Diffusion bonded joints were solution treated at 495℃ for 14 h and then aged at 200℃ for 30 h.Microstructures and mechanical properties of joints were analyzed.The results showed that rare earth elements and their compounds gathering at bonding interface hindered the grain boundary migration crossing bonding interface.Tensile strength of as-bonded and as-solution treated joints increased firstly and then decreased with the bonding temperature increasing due to the combined effects of grain coarsening and solid-solution strengthening.As-bonded and solution-treated joints fractured at matrix except the joint bonded at 400℃,while aged joints fractured at bonding interface.The highest ultimate tensile strength of 279 MPa with elongation of 2.8%was found in joint bonded at 440℃ with solution treatment followed by aging treatment.在焊接压力6 MPa、保温时间90 min、不同焊接温度(400~480℃)下对Mg-6 Gd-3Y铸态镁合金进行真空扩散焊试验,对焊后接头进行(495℃,14 h)固溶和(200℃,30 h)时效处理,并对接头显微组织和力学性能进行分析。结果表明:稀土元素及其化合物聚集在焊接界面上,阻碍晶界向焊接界面另一侧迁移。由于晶粒粗化和固溶强化的综合影响,焊接态和热处理态接头的抗拉强度均随初始焊接温度增加呈现先增后降的趋势。除焊接温度400℃处理后的接头外,其他焊接态及固溶处理态的接头均断于母材,而所有接头经固溶时效处理后均断于焊接界面。焊接温度为440℃时的接头经固溶时效处理后的抗拉强度最高(279 MPa),此时断后伸长率为2.8%。

关 键 词：Mg−Gd−Y alloy vacuum diffusion bonding post-weld heat treatment bonding interface bonding strength 

分 类 号：TG156[金属学及工艺—热处理] TG453.9[金属学及工艺—金属学]