摘要:
通过添加钒/镍复合中间层,在1 050℃/10 MPa/1 h的工艺条件下,对钨/钢异种材料进行真空扩散焊接.采用扫描电镜(SEM)、能谱仪(EDS)、电子探针(EPMA)、纳米压痕、X射线衍射对接头的微观组织、元素分布及显微硬度进行分析和测试;对焊接接头的拉伸性能进行测试,并对拉伸断口的形貌特征,元素分布及物相组成进行分析.结果表明,采用钒/镍复合层可实现钨与钢的可靠焊接;钨/钢焊接接头界面区由钨-钒固溶体层、未反应的钒层、钒-镍界面层、未反应的镍层、镍-铁固溶体层五部分组成,其中钒-镍界面层结构为碳化钒层/钒-镍金属间化合物和碳化钒混合层/钒-镍金属间化合物层;钒/镍界面由于硬脆碳化物与金属间化合物的产生,具有最高的显微硬度,硬度高达9.7 GPa;接头强度达164 MPa,断裂点位于含脆性相碳化钒及钒-镍金属间化合物的钒/镍界面.
Abstract:
The diffusion welding characteristic between W and ferrite steel(FS) interface was investigated in vacuum hot pressing furnace at 1 050℃ for 1h with 10 MPa, using 3 mm V foil and 1 mm Ni foil as interlayer. The microstructure, element compositions, phase compositions and microhardness of joints were observed and measured with field-emission scanning electron microscopy(FE-SEM), energy dispersive spectroscopy(EDS), electron probe micro-analyzer(EPMA), x-ray diffractometer(XRD) and nanoindenter, respectively. The tensile strength was tested by mechanical testing machine. The results showed that, a reliable bonding between W and FS could be gained by using vanadium/nickel composite interlayer. The W/FS joint consisted of a multilayer sandwich structure, including the transition zone of W/V, the residual V interlayer, the diffusion layer of V/Ni, the residual Ni interlayer and the diffusion layer of Ni/FS. Meanwhile, the transition zone of W/V and Ni/FS were mainly composed of solid solution structure and the V/Ni diffusion layer with the highest microhardness of 9.7GPa. The joint had a multilayered structure consisting of VC layer/mixing layer of VC and Ni-V intermetallics/Ni-V intermetallics layerand the tensile strength of joint reached 164 MPa and the samples fractured through the V/Ni interface because of the presence of brittle VC phase and Ni-V intermetallics.
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