Abstract In this work, effects of rare earth elements on microstructure evolution and wear properties of TiB2 reinforced aluminum matrix composite coatings were investigated by the combination of first principles calculations and experimental investigation. The calculated results revealed that Sc exhibited the most effective modification ability due to the most negative adsorption energy and the largest charge transfer compared with La and Y. Based on the calculated results, the rare earth elements modified composite coatings were synthesized by laser processing. The as-obtained composites were characterized by back-scattered electron imaging (BSE) and spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM). Results indicated that the addition of Sc can greatly refine the particle size of TiB2, improve the distribution of particles and lead to the morphology transforming from hexagonal disk to sphere. As a result, the microhardness and wear properties of the composite coatings were enhanced significantly. The best properties were achieved in the composite with 0.6 wt% Sc addition, which exhibited highest microhardness of 920 HV, lowest friction coefficient of 0.4 and wear rate of 24.8 mg /h. The preferential adsorption of rare earth elements on TiB2 facets is proposed to be the main modification mechanism which results in the morphology evolution and wear properties improvement.

中文翻译：

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稀土元素对TiB2增强铝基复合涂层组织和磨损性能的影响：实验和第一性原理计算

摘要 本工作通过第一性原理计算和实验研究相结合，研究了稀土元素对TiB2增强铝基复合涂层组织演变和磨损性能的影响。计算结果表明，与La和Y相比，Sc具有最大的负吸附能和最大的电荷转移，因此表现出最有效的改性能力。基于计算结果，通过激光加工合成了稀土元素改性复合涂层。所获得的复合材料通过背散射电子成像 (BSE) 和球差校正扫描透射电子显微镜 (Cs 校正 STEM) 进行表征。结果表明，Sc的加入可以大大细化TiB2的粒径，改善颗粒的分布并导致形态从六边形圆盘转变为球体。结果，复合涂层的显微硬度和磨损性能显着提高。在添加 0.6 wt% Sc 的复合材料中获得了最佳性能，其显微硬度最高为 920 HV，最低摩擦系数为 0.4，磨损率为 24.8 mg / h。稀土元素在 TiB2 面上的优先吸附被认为是导致形貌演变和磨损性能改善的主要改性机制。添加 6 wt% Sc，其显微硬度最高为 920 HV，最低摩擦系数为 0.4，磨损率为 24.8 mg / h。稀土元素在 TiB2 面上的优先吸附被认为是导致形貌演变和磨损性能改善的主要改性机制。添加 6 wt% Sc，其显微硬度最高为 920 HV，最低摩擦系数为 0.4，磨损率为 24.8 mg / h。稀土元素在 TiB2 面上的优先吸附被认为是导致形貌演变和磨损性能改善的主要改性机制。