A nickel-based superalloy Inconel 718 ultrathin-walled structure was manufactured by high-temperature brazing using Ni-Cr-Si filler metal. The microstructure in the brazed fillet was analysed, and the solidification behaviour and the formation of the eutectic island in the brazed fillet were investigated. The effects of post-bond heat treatment (PBHT) with different temperatures and durations on the microstructural evolution and mechanical properties of the brazed ultrathin-walled structure were investigated in detail. The results indicate that PBHT at a relatively high temperature significantly affects the mechanical properties of the ultrathin-walled structure, which is attributed to the formation of the precipitates at a deeper location in the base metal. In addition, the mechanical performance is enhanced by the generation of δ- and γ''-phases under relatively low temperatures (980 °C and 740 °C). On the other hand, the decrease in mechanical performance is caused by the formation of network-like precipitates and the Ni-Si-Nb phase at the grain boundary over extended ageing times. By analysing the fracture mode evolution and the propagation of cracks in the brazing fillet, the effect of PBHT on fracture morphology evolution is determined primarily by the proportion of brittle fractures and the formation of the strengthening phase in the base metal.

通过使用Ni-Cr-Si填充金属进行高温钎焊来制造镍基超合金Inconel 718超薄壁结构。分析了钎焊圆角的微观组织，研究了钎焊圆角的凝固行为和共晶岛的形成。详细研究了不同温度和持续时间的键合后热处理（PBHT）对钎焊超薄壁结构的微观组织演变和力学性能的影响。结果表明，较高温度下的PBHT会显着影响超薄壁结构的机械性能，这归因于在贱金属中更深处形成沉淀。此外，通过生成δ-和γ''可增强机械性能 相处于相对较低的温度（980°C和740°C）下。另一方面，机械性能的下降是由于在延长的时效时间内在晶界处形成了网状析出物和Ni-Si-Nb相而引起的。通过分析钎焊圆角处的断裂模式演变和裂纹扩展，PBHT对断裂形态演变的影响主要取决于脆性断裂的比例和母材中强化相的形成。