FGH98粉末高温合金瞬时液相扩散焊接头组织和性能

Microstructure and properties of FGH98 powder superalloy joints by transient liquid phase diffusion bonding

采用Ni-Cr-Mo-B中间层对FGH98高温合金进行瞬时液相扩散焊,研究保温时间对接头显微组织、力学性能和断裂行为的影响.结果表明:非等温凝固区中的共晶相为富Ni硼化物γ-Ni固溶体,等温凝固区主要有γ-Ni固溶体,扩散影响区中含有多种形貌的硼化物.随着保温时间的延长,非等温凝固区的共晶相逐渐减少并消失,扩散影响区的宽度增加,接头的剪切强度也逐渐增加.增加保温时间,硼元素扩散距离增加,导致扩散影响区中硼化物析出相密度降低.保温时间为120 min时接头完全等温凝固,剪切强度达到724 MPa,接头断裂出现在扩散影响区中,断裂模式为韧性断裂.

The Ni-Cr-Mo-B interlayer was used to perform transient liquid phase diffusion bonding of FGH98 superalloy.The effect of bonding time on the microstructure,mechanical properties and fracture behavior of the joint was investigated.The results indicated that the eutectic phases in the athermal solidification zone(ASZ)were Ni-rich borides andγ-Ni solid solution.The isothermal solidification zone(ISZ)was mainly composed ofγ-Ni solid solution,and the diffusion affected zone(DAZ)contained boride with a variety of morphologies.With the increase of bonding time,the eutectic phase in ASZ gradually decreased and disappeared,the width of DAZ increased and the shear strength of the joint also gradually increased.Increasing the bonding time,the diffusion distance of boron element increased,resulting in a decrease in the density of boride precipitates in DAZ.When the joint was held for 120 min,it achieved complete isothermal solidification,reaching a shear strength of 724 MPa.The joint fracture occurred in DAZ,exhibiting a ductile fracture mode.Highlights:(1)The Ni-Cr-Mo-B interlayer alloy was autonomously designed and prepared.(2)The time required for isothermal solidification of FGH98 alloy by transient liquid phase diffusion bonding was predicted.(3)The effect of different bonding time on the microstructure and mechanical properties of FGH98/Ni-Cr-Mo-B/FGH98 transient liquid phase diffusion bonded joint was clarified.