基于铜中间层的钛合金与不锈钢的真空扩散焊研究

Vacuum diffusion welding of titanium alloy and stainless steel with copper interlayer

采用纯Cu箔为中间层在真空钼丝烧结炉中进行TC4和304的扩散连接,利用光学显微镜(OM)、扫描电子显微镜(SEM)和能谱仪(EDS)对接头组织和成分进行表征,并测试结合区的显微硬度。结果表明,Cu作为中间层有效抑制了Ti与Fe、Cr的互扩散,不同焊接温度下均形成3个新相层。A层主要为富集Ti、Cu形成的混合Fe基固溶体;B层主要为TiCu金属间化合物、β-Ti(Fe)及Fe-Cu共析混合物;C层主要是β-Ti为基的混合固溶体和少量Ti-Cu化合物。过渡层生成Cu Ti2、Cu3Ti2,主要分布在B、C层。焊接温度为1 050℃、保温为60 min时,焊接缺陷较少,具有良好的焊接质量。结合区厚度适中,组织分布较均匀,显微硬度在A/B界面附近达到峰值,为667.2HV。

TC4/Cu/304 composite materials were prepared with copper as the intermediate layer in a vacuum molybdenum wire sintering furnace. The microstructure and constituents of transition layer were characterized by optical microscope （OM） , scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）, and the microhardness was tested as well. The results show that Cu as an intermediate layer in the composites can effectively inhibit the interdiffusion of Ti in Fe and Cr. Three new phases were formed at all different welding temperatures. The layer A is mainly composed of Fe based solid solution enriched with Ti, Cu. The layer B is mainly composed of eutectoid reaction mixture of Ti-Cu intermetallic compound, β-Ti （Fe） and Fe-Cu, and the layer C is mainly composed of β-Ti based mixed solid solution and Ti-Cu compound. The CuTi2, and Cu3Ti2 metal compounds were formed in the transition layer, which are mainly distributed in the B and C layers. The TC4/Cu/304 composites with less welding defects and good welding quality were prepared at 1 050 ℃ for 60 min. The thickness of the bonding zone is moderate, and the microstructure is homogeneous. The highest microhardness reaches 667.2HV near the A/B interface.