硬质合金与钛合金真空扩散焊工艺研究

Diffusion Bonding of Hard Metal and Titanium Alloy

通过对硬质合金（YG8）与钛合金（TA15）异种材料焊接工艺问题的分析，采用塑性较好的Cu作为中间层来缓解TA15／YG8接头热应力。在选取焊接温度为860℃，压力为5MPa，以及扩散焊时间分别为10、20、30、50、60min的条件下，研究YG8与TA15的扩散焊工艺，分析了YG8与TA15连接界面的原子扩散机制、反应相生成及其分布规律。结果表明，YG8／Cu界面呈一条亮线，结合良好，而TM5／Cu界面由于生成层状分布的脆性金属间化合物而出现裂纹，剪切试验时接头也是在此界面断开。在扩散焊时间为60min时接头剪切强度达到116MPa。

The residual stress of the Titanium alloy （TA15） ＆ hard metal （YG8） joint was relaxed by using Copper foil as interlayer. Diffusion bonding was carried out between YG8 and TA15 at the 860＊（2, respectively for 10, 30, 60, 90 rnin under invariable axial pressure of 5 MPa. After the bonding, the diffusion mechanism of atoms and microstructure of the diffusion zone were obtained by means of scanning electron microscopy （SEM）, when Cu foil was employed as the interlayer between specimens, and the growth of reaction phases and their distributing in the joint of YG8/TA15 were also investigated. The results showed the interface of YG8J Cu takes on a bright line and bonded well, while the properties of TA15/Cu interface worsened because of the occurrence of Ti - Cu intermediates and broke at the interface. So the volume and the distribution characteristics of the intermediates should be controlled in the bonding process,and the relationship between the sheer strength of the joint and the bonding parameters was analyzed. It has also been found that the sheer strength of joint was improved to 116MPa under the optimized parameters.