(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 采用镍基微晶箔带作为钎料，在1150 ℃、30 min的工艺条件下研究直接钎焊和添加Ni-Cu合金中间层两种工艺焊接钨和钢的特性。采用扫描电镜(SEM)、电子探针(EPMA)和纳米压痕分别对接头的显微组织、元素分布及显微硬度进行分析，测试接头的拉伸强度并分析断口形貌和物相组成。结果表明：添加Ni-Cu合金中间层的钎焊接头的拉伸强度(300 MPa)远高于直接钎焊的焊接接头的拉伸强度。两种钎焊接头的断裂均发生在残余应力集中的靠近钨/钎料界面的钨基体内，为典型的脆性断裂方式。接头界面硬度分析表明，固溶强化效应及脆性化合物的生成，使靠近钨侧的钨/钎料扩散区域的显微硬度得到显著增加。
关键字: 钨；钢；真空钎焊；镍基钎料；显微组织；力学性能；显微硬度
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:A brazing process, using a rapidly solidified Ni-based foil-type filler, was performed to investigate the joining of tungsten and steel with/without an interlayer Ni-Cu at 1150 ℃ for 30 min. The cross sectional microstructure, element compositions and microhardness distribution of the joint region were analyzed by scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and nano-indenter, respectively. The tensile strength of the joints was measured by mechanical tests, and then the microstructure and element compositions of the fracture were analyzed. The results indicate that the tensile strength of the as-bonded W/Ni-Cu/FS joints (300 MPa) is much higher than that of the as-bonded W/FS joints. Both W/FS and W/Ni-Cu/FS joints appear a brittle fracture mode and fracture in tungsten matrix which is close to the interface. The micro-hardness analysis of joint interface reveals that solid solution strengthening effect and the generation of brittle compounds are responsible for an increasing micro-hardness in inter-diffusion layer between the filler and W.
Key words: tungsten; steel; vacuum brazing; Ni-based foil-type filler; microstructure; mechanical property; micro- hardness
