硼稀土共渗钛合金的耐蚀性研究

采用不需保护性气氛的固体粉末法对Ti6Al4V(TC4)合金表面进行稀土与硼共渗，并对硼稀土共渗TC4钛合金、单渗硼TC4钛合金及未经渗硼处理的TC4钛合金基体，分别在35%NaCl和5%H2SO4(质量分数)溶液介质中进行了腐蚀实验.X射线衍射分析表明，TC4表面渗层由TiB2和TiB组成.扫描电镜观察表明，外层的TiB2具有平坦的生长前沿，而内层TiB为锯齿状形貌；其中外层的TiB2内部存在少量针孔，分析认为是Ce原子与B原子共渗时产生的Kirkendall效应所致.Tafel极化曲线分析结果表明，在35%NaCl和5%H2SO4溶液介质中，各样品的耐蚀性大小排序为单渗硼TC4钛合金>硼稀土共渗TC4钛合金>未经渗硼处理的TC4钛合金.

Corrosion Resistance of Rare Earth-Borided Titanium Alloy

Rare earth and B atoms were penetrated into Ti6Al4V (TC4) alloy surface using the solid powder technique without protective atmosphere. The rare earth-borided, borided and TC4 alloys were corroded in the 3.5wt% NaCl and 5wt% H2SO4 solutions, respectively. The X-ray diffraction analysis shows that the borided layer on the TC4 surface is composed of TiB2 and TiB. Scanning electron microscopy study shows that the outer TiB2 layer has a flat growth front, while the inner TiB layer appears serration. Some pinholes present in the outer layer, which may be due to the Kirkendall effects caused by the co-diffuse of Ce and B atoms synchronically. The Tafel polarization curve shows that, in the 3.5wt% NaCl and 5wt% H2SO4 solution, the corrosion resistance of the samples follows the order of borided, rare earth-borided and TC4 alloy.