Effect of Hydrogen on Diffusion Bonding Behavior and Mechanism of Ti-6Al-4V alloy

摘要:

研究了置氢Ti-6AL-4V 合金在800~860 ℃温度范围内气压扩散连接行为与机理。在840 ℃对置氢0.11%（质量分数，下同）的纯钛和Ti-6AL-4V 合金进行了扩散连接。应用光学显微镜（OM）、扫描电子显微镜（SEM）和电子探针显微分析仪（EPMA）研究了氢对扩散连接接头焊合率及元素扩散行为的影响。结果表明：氢能够显著提高扩散连接接头的焊合率（置氢0.11%在840 ℃的焊合率大于98%）；氢含量为0.11%的Ti-6Al-4V合金扩散连接后仍为等轴组织，而高氢含量（0.32%~0.48%H）Ti-6Al-4V合金扩散连接后组织转变为粗大的魏氏组织；氢对扩散连接行为的改善作用主要是由于氢的弱键效应及其对元素扩散系数的提高；相对于未置氢Ti-6Al-4V合金，0.11%的氢能够将Al和V元素的扩散系数提高一个数量级，并使扩散连接温度降低了40 ℃。

Abstract:

The hydrogenated commercially pure titanium and Ti-6AL-4V alloy with 0.11wt%H were diffusion-bonded in the temperature range from 800 to 860 °C. The interface and elements diffusion were observed by OM, SEM and EPMA. The results show that hydrogen significantly improves the rate of diffusion bonding (bonding rate is up to 98% under the condition of 0.11 wt%H at 840 °C). An equiaxed microstructure is maintained due to the addition of 0.11 wt%H after bonding while the higher amount of hydrogen (0.32 wt%~0.48 wt%H) results in a coarse widmanstatten structure. The improved performance of the diffusion bonding induced by hydrogen is mainly attributed to the weak-bond effect and the increase of diffusion coefficient of the elements. The addition of 0.11 wt%H brings one order increase of magnitude to the diffusion coefficient of Al and V element, as well as 40 °C lower diffusion bonding temperature compared with non-hydrogen Ti-6Al-4V alloy.