In this study, diffusion brazing was employed to join IN718 superalloy and AISI 316 L stainless steel using MBF-20 amorphous interlayer. The effect of interlayer thickness (50−150 μm) was studied on the microstructure and mechanical properties of the joints. The joints were characterized by using optical and scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction analysis. Microhardness and shear tests were used to assess the mechanical properties of the joints. The microstructural investigations revealed that eutectic phases including γ solid solution, Ni₃B, CrB, Cr₂B₃ and Ni₆Si₂B were formed at the joint centerline of the sample with incomplete isothermal solidification during holding at the brazing temperature. Fine Ni₃Si particles also precipitated via a solid state transformation during cooling in the vicinity of eutectic phases. Mechanism of microstructure evolution and the solidification behavior of the centerline intermetallic compounds were discussed. In addition, Cr-, Mo-, Nb-rich borides precipitated in the DAZ of IN718 side and the precipitates formed in the DAZ of AISI 316 L side were Cr-, Mo-rich and Fe-, Cr-rich borides. The maximum shear strength of 440 MPa was obtained for the sample with complete isothermal solidification. Fractography of the samples after the shearing test indicated that the sample with complete isothermal solidification exhibits a ductile failure mode, however a brittle fracture happens in the samples containing hard eutectic constituents at the joint centerline.

在这项研究中，采用MBF-20非晶夹层将扩散钎焊用于连接IN718高温合金和AISI 316 L不锈钢。研究了层间厚度（50-150μm）对接头组织和力学性能的影响。通过使用光学和扫描电子显微镜，能量色散谱和X射线衍射分析来表征接头。显微硬度和剪切试验用于评估接头的机械性能。显微组织研究表明，共晶相包括γ固溶体，Ni ₃ B，CrB，Cr ₂ B ₃和Ni ₆ Si ₂在保持钎焊温度的过程中，在等温凝固不完全的情况下，在试样的接合中心线形成了B。细镍₃在冷却期间，在共晶相附近，Si颗粒也通过固态转变而沉淀。讨论了中心线金属间化合物的组织演变机理和凝固行为。另外，在IN718侧的DAZ中析出了富含Cr，Mo，Nb的硼化物，在AISI 316 L侧的DAZ中形成了析出物为Cr，Mo和Fe，Cr的硼化物。完全等温固化的样品的最大剪切强度为440 MPa。剪切试验后样品的分形图表明，等温完全凝固的样品表现出延性破坏模式，但是在接头中心线处含有硬质共晶成分的样品发生脆性断裂。