Influence of mixed brazing filler metal on microstructure and mechanical properties of wide gap brazed joints of nickel-based single crystal superalloy
Influence of mixed brazing filler metal on microstructure and mechanical properties of wide gap brazed joints of nickel-based single crystal superalloy
[Objective]A method combining a new type of nickel-based brazing filler metal with high-melting-point alloy powder that matched composition of base material was used to create mixed brazing filler metal.Effect of particle size and proportion of added high-melting-point alloy powder on microstructure and mechanical properties of brazed joints was explored.[Methods]Precipitated phase,element distribution and microstructure of brazed joints were analyzed by scanning electron microscope,and hardness and creep life of brazed joints were tested.[Results]It revealed that brazed joints mainly consisted of filler alloy zone(FAZ),interface bonding zone(IBZ)and diffusion affected zone(DAZ).FAZ predominantly comprised M3B2 and M8B type borides,along with γ/γ′phases.IBZ was composed of γ and γ′precipitation-strengthened phases.When alloy powder particle size was 44 μm and 75 μm,defect-free brazed joints were obtained.However,pores defects formed in brazing seam when particle size reached 177 μm.[Conclusion]As the proportion of alloy powder increased,there was a rise in microhardness of bonding area of brazed joints.When alloy ratio was increased from 30%to 50%,creep life of brazed joints extended from 15 h to 34 h.However,further increasing proportion to 60%led to a reduction in creep life of brazed joints to 0.6 h.The results of this study provided a theoretical basis and reference value for realizing connection and repair of high-temperature hot-end components in engineering applications.
关键词
镍基单晶高温合金/混合粉末钎料/大间隙钎焊/持久性能
Key words
nickel-based single crystal superalloy/mixed powder brazing filler metal/wide gap brazing/creep life
维普
万方数据