Ni-Cr合金保护气氛钎焊金刚石界面Cr_7C_3的形核与长大

Nucleation and growth of Cr_7C_3 at interface of brazed diamond with Ni-Cr alloy under protective atmosphere

采用Ni-Cr合金在保护气氛炉中进行钎焊单晶金刚石磨粒试验,使用SEM对Ni-Cr合金钎焊金刚石界面碳化物、断口形貌、钎缝组织进行观察分析,采用XRD对钎焊后金刚石进行物相分析.结果表明,在保护气氛炉中进行钎焊可以实现金刚石的高强度连接,钎焊后金刚石棱角清晰、形貌完好.金刚石的表面生成具有方向性的Cr3C2,Cr3C2的生长方向与金刚石(111)晶面有一定的位向关系,与其所在晶面六边形的边平行,Cr7C3全部在Cr3C2上形核长大,最后形成外层是Cr7C3,内层是具有方向性的Cr3C2.

In protective atmosphere furnace,mono-crystalline diamond was brazed with Ni-Cr alloy,the morphology of the carbide formed on the surface of diamond,fracture appearance and microstructures of the brazed seam were analyzed with scanning electron microscope and XRD.The results show that the diamond brazed in protective atmosphere furnace can realize high strength bonding.The brazed diamond has distinct edge and intact morphology.On the surface of the diamond,the arrangement of Cr3C2 is regular,the growth directions take on certain orientation relationship with the(111) crystal planes of diamond.All of Cr7C3 nucleate and grow on the surface of Cr3C2.Finally,the exothecium Cr7C3 and regular arrangement endothecium Cr3C2 were formed.