Abstract

Ti–6Al–4V alloy was borided by using a two-stage boriding process. In the first stage, boron atoms accumulated on Ti–6Al–4V alloy samples via electron beam evaporation technique. The second stage included annealing of samples after boron deposition at various temperatures in order to achieve boride layer with high hardness and adherence. After the boriding treatment, phases formed on the surface of the Ti–6Al–4V alloy were identified by X-ray diffraction technique. The microstructure and thickness of boride layers were examined by scanning electron microscope. Microstructural analyses indicated that surface structure of borided samples comprised of TiB₂ layer on the top and TiB whiskers towards the substrate. It was revealed that boriding by electron beam evaporation technique resulted in formation of a hard and adhered surface structure after annealing especially at 950°C for 24 h. Microhardness measurements showed that boride layer on Ti–6Al–4V has mean hardness value of about 1937 HV. Boriding at 950°C for 24 h brought about an improvement in wear resistance of Ti–6Al–4V alloy. The borided surface exhibited higher wear resistance along with higher coefficient of friction as compared to as-received one.

中文翻译：

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电子束蒸发技术表征Ti-6Al-4V合金上形成的硼化物层

摘要

Ti–6Al–4V合金通过两步硼化工艺进行了硼化处理。在第一阶段，硼原子通过电子束蒸发技术沉积在Ti-6Al-4V合金样品上。第二阶段包括在各种温度下在硼沉积后对样品进行退火，以实现具有高硬度和附着力的硼化物层。经过硼化处理后，通过X射线衍射技术鉴定了在Ti-6Al-4V合金表面形成的相。用扫描电子显微镜检查硼化物层的微观结构和厚度。显微组织分析表明，硼化样品的表面结构由TiB _2组成顶部的TiB层和朝向衬底的TiB晶须。揭示了通过电子束蒸发技术进行的硼化导致特别是在950℃下退火24小时后形成坚硬且粘附的表面结构。显微硬度测量表明，Ti-6Al-4V上的硼化物层的平均硬度值为1937 HV。在950°C的条件下硼化24 h可以改善Ti-6Al-4V合金的耐磨性。与原样相比，硼化的表面表现出更高的耐磨性以及更高的摩擦系数。