采用金箔钎焊连接石墨与Hastelloy N合金

Brazing graphite to Hastelloy N superalloy using pure Au foil

关键词:  石墨–哈氏合金接头  钎焊  接头组织  力学性能

Key words:  Graphite–Hastelloy N alloy joint  Brazing  Joint's Microstructure  Mechanical property

摘要:

采用纯金箔在1 333 K、不同保温时间（1~90 min）下钎焊连接石墨与Hastelloy N合金，研究了保温时间对接头内显微组织及力学性能的影响.结果表明，钎缝组织主要由金基固溶体、镍基固溶体及在其内弥散分布的Mo₂C颗粒组成；近钎缝的Hastelloy N合金内的晶内和晶界位置分别析出细小的Mo₂C及Mo₆Ni₆C颗粒.当保温时间提升至60 min时，抗剪强度随保温时间的延长变化不大；保温90 min后，由于临近钎缝侧的Hastelloy N合金内的晶内和晶界处分别析出大量细小的Mo₂C和Mo₆Ni₆C颗粒形成了类似金属基复合材料组织，使得抗剪强度提高到34.1 MPa，与石墨强度相当.钎焊后接头内形成热膨胀系数梯度过渡结构导致了接头内低的应力水平，获得了高品质接头.文中开展的研究将为熔盐堆的建设提供必要的技术支撑.

Abstract:

Pure Au foil was used to braze graphite and Hastelloy N alloy at 1 333 K with different holding time (1~90 min), and the effect of holding time on the microstructure and mechanical propertithe of welding joints was researched. The results showed that the brazing seam basically consists of Au (s.s), Ni (s.s) and the Mo₂C particles scattered in brazing seam. Mo₂C and Mo6Ni6C particles were precipitated in the grains and at the grain boundary of Hastelloy N alloy near the brazing seam. With the holding time increasing to 60 min, the joint average shear strength changed little with the extension of holding time. When the holding time is 90 min, due to the precipitation of Mo₂C and Mo₆Ni₆C particles in the grains and at the grain boundaries in the Hastelloy N beside the brazing seam, the particles constituted the material which liked the metal matrix composite. It is the reason why joint strength reached maximum 34.1 MPa which similar to the strength of the graphite substrates. The thermal expansion coefficient gradient transition structure that formed in the joint after brazing resulted in low stress level in the joint and high quality joint was obtained. The performed investigation will provide necessary technical support for the construction of molten salt reactor.