(中南大學(xué) 粉末冶金國家重點(diǎn)實驗室，長沙 410083)
摘 要: 采用鎳基微晶箔帶作為釬料，在1150 ℃、30 min的工藝條件下研究直接釬焊和添加Ni-Cu合金中間層兩種工藝焊接鎢和鋼的特性。采用掃描電鏡(SEM)、電子探針(EPMA)和納米壓痕分別對接頭的顯微組織、元素分布及顯微硬度進(jìn)行分析，測試接頭的拉伸強(qiáng)度并分析斷口形貌和物相組成。結(jié)果表明：添加Ni-Cu合金中間層的釬焊接頭的拉伸強(qiáng)度(300 MPa)遠(yuǎn)高于直接釬焊的焊接接頭的拉伸強(qiáng)度。兩種釬焊接頭的斷裂均發(fā)生在殘余應(yīng)力集中的靠近鎢/釬料界面的鎢基體內(nèi)，為典型的脆性斷裂方式。接頭界面硬度分析表明，固溶強(qiáng)化效應(yīng)及脆性化合物的生成，使靠近鎢側(cè)的鎢/釬料擴(kuò)散區(qū)域的顯微硬度得到顯著增加。
關(guān)鍵字: 鎢；鋼；真空釬焊；鎳基釬料；顯微組織；力學(xué)性能；顯微硬度
（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
