采用Nb中间层扩散连接Zr-4合金接头界面组织与性能  

Microstructures and properties of Zr-4 alloy diffusion bonding joint with Nb interlayer

作　　者：王瑞萍 肖宗林 杨旭[1] 王泽明[2] 王颖[1] 杨振文[1] WANG Ruiping;XIAO Zonglin;YANG Xu;WANG Zeming;WANG Ying;YANG Zhenwen(Tianjin Key Laboratory of Advanced Joining Technology,Tianjin University,Tianjin,300354,China;Nuclear Power Institute of China,Chengdu,610041,China)

机构地区：[1]天津大学,天津市现代连接技术重点实验室,天津300354 [2]中国核动力研究设计院,成都610041

出　　处：《焊接学报》2024年第8期33-40,共8页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(52174369);天津市自然科学基金(20JCYBJC01300)。

摘　　要：为提高Zr-4合金扩散焊接头强度,降低有效连接温度,采用不同厚度的Nb中间层在760℃/30 min/7 MPa条件下扩散连接Zr-4合金,分析了Nb中间层的加入及其厚度对接头界面组织和性能的影响.结果表明,在扩散连接过程中,界面处Zr和Nb原子相互扩散形成由(Zr,Nb)固溶体构成的扩散层,且扩散层厚度随着中间层厚度的增加基本不变,靠近Nb侧的扩散层中观察到Zr(Cr,Fe)_(2)和Zr(Fe,Nb)_(2)第二相的生成.在760℃条件下,Zr-4合金直接扩散焊接头抗拉强度仅为75MPa,存在大量未连接区域,添加Nb中间层可显著提高界面结合率,接头抗拉强度达到450 MPa,接头抗拉强度和断后伸长率随着Nb中间层厚度的增加稍有下降,在添加20μm中间层时最大,分别为450 MPa和13.1%,且断裂位置由Zr-4合金基体(20μm)转变为界面扩散层(50μm和80μm).Zr-4合金扩散焊接头在经历400℃,10.3 MPa的过热蒸气腐蚀后,扩散层发生明显腐蚀现象,腐蚀深度最大达到108.39μm,接头抗拉强度和断后伸长率下降至415 MPa和5.1%,断裂位置在连接界面处,断口中发现Zr(Fe,Nb)_(2)相.To improve the strength of Zr-4 alloy diffusion bonding joints and reduce the effective bonding temperature,different thicknesses of Nb interlayer were used for the Zr-4 alloy diffusion bonding at 760°C/30 min/7 MPa.The effect of the Nb interlayer and its thickness variation on the microstructures and properties of the joints was investigated.During the diffusion bonding process,the diffusion layer was formed by the mutual diffusion of Zr and Nb,which was composed of(Zr,Nb)solid solution,and its thickness was constant with the increase of the Nb thickness.Secondary phases of Zr(Cr,Fe)_(2)and Zr(Fe,Nb)_(2)were observed in the diffusion layer near the Nb interlayer.The tensile strength of the joints was only 75 MPa at 760℃and many unbonded areas existed.The tensile strength and elongation of the joints decreased slightly with the increase of Nb thickness,and reached the maximum of 450 MPa and 13.1%,respectively,with the 20μm Nb interlayer.The fracture position was changed from the Zr-4 matrix(20μm)to the diffusion layer(50μm,80μm).After superheated steam corrosion of 400℃and 10.3 MPa,obvious corrosion occurred at the diffusion layer of the Zr-4/Nb/Zr-4 joint.The maximum corrosion depth was 108.39μm,and the tensile strength and elongation of the joints decreased to 415 MPa and 5.1%.The Zr(Fe,Nb)_(2)phases were found on the fracture surface.

关 键 词：扩散焊 ZR-4合金 Nb中间层 腐蚀性能 

分 类 号：TG453.9[金属学及工艺—焊接]