K480镍基高温合金钎焊接头组织与性能  

Microstructure and mechanical properties of K480 nickel-based superalloy brazed joint

作　　者：王浩 吴欣 程耀永 毛唯 Wang Hao;Wu Xin;Cheng Yaoyong;Mao Wei(AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]中国航发北京航空材料研究院,北京100095

出　　处：《焊接》2022年第4期37-42,47,共7页Welding & Joining

摘　　要：采用Ni-Nb-W-Co-Cr-Al钎料对K480高温合金进行真空钎焊,通过扫描电镜和能谱分析研究了钎焊接头微观组织和钎焊保温时间对微观组织的影响,通过拉伸试验机研究了钎焊接头高温拉伸性能的变化规律。结果表明,在1220℃×15 min镍基钎料可与高温合金粉末发生冶金反应生成致密完整的钎焊接头。钎焊接头主要由高温合金粉末颗粒、γ+γ′共晶相、含Si硼化物相和富Nb的Ni_(3)Si相组成。与此同时,钎料中的Nb,W等元素向母材发生扩散生成(Nb,Ti)C和(Mo,W,Cr,Ni)_(3)B_(2)相。随着钎焊保温时间延长,合金粉末颗粒不断长大,接头中脆性化合物总量减少,含Si的硼化物逐渐由块状、条状转变为骨架状(Mo,W,Cr,Ni)_(3)B_(2)相,保温时间超过1 h,接头内出现大尺寸孔洞缺陷。保温时间为15 min时可获得最佳的接头性能,980℃高温拉伸强度为585 MPa,达到母材性能的90%以上。保温时间超过1 h后,钎焊接头高温拉伸性能出现下降趋势,其原因主要是由于(Mo,W,Cr,Ni)_(3)B_(2)骨架状结构和大尺寸孔洞缺陷的出现所致。K480 nickel-based superalloy was brazed with Ni-Nb-W-Co-Cr-Al nickel-based filler.Microstructure of the joints and effect of brazing holding time on microstructure were studied with scanning electron microscopy.The high temperature tensile properties were studied with tensile testing machine.A dense and complete brazed joint was formed with metallurgical reaction between nickel-based filler and superalloy powder at 1220°C for 15 min.The joint was mainly composed of high melting point alloy powder,γ+γ′eutectic phase,boride phase with Si,and Nb-rich Ni_(3)Si phase.(Nb,Ti)C and(Mo,W,Cr,Ni)_(3)B_(2)phases were formed by diffusion of Nb and W elements to the base metal.With the extension of brazing holding time,the alloy powder particles grew up,and the total amount of brittle compounds in the joint decreased.However,the boride phase with Si gradually changed from block or strip to(Mo,W,Cr,Ni)_(3)B_(2)skeleton structure.When holding time exceeded 1 h,large-size cavity defects appeared in the joints.When holding time was 15 min,the best properties of joint could be obtained,and the tensile strength at 980℃was 585 MPa,which was more than 90%that of the base metal.When holding time exceeded 1 h,high temperature tensile properties of the brazed joints showed a downward trend,which was mainly due to the appearance of(Mo,W,Cr,Ni)_(3)B_(2)skeleton structure and large-size cavity defects.

关 键 词：K480合金 镍基钎料 微观组织 力学性能 

分 类 号：TG454[金属学及工艺—焊接]