Abstract In this paper, a laser cladding process was proposed to obtain ultrafine eutectic Fe-Nb-B alloy coatings on AISI 1020 steel substrate in which the power and scanning speed were defined. The laser cladding process can be used as a rapid solidification processing route to produce single laser tracks and coatings (overlapped tracks) with pre-placed powders deposited onto a mild steel substrate in order to obtain a minimal dilution between the coating/substrate. This research aims to produce a coating of Fe74.25Nb8.25B17.5 (at.%) alloy over the AISI 1020 steel substrate by laser cladding using a pre-placed powder method to investigate the parameters on coating production, dilution, microstructure, and properties. The final goal is to find an appropriate processing parameter range to obtain coatings with high hardness and possibly good wear resistance. The microstructure and behavior of powder, cladding layers and coatings were examined by X-ray Diffractometry, Differential Scanning Calorimetry, Scanning Electron Microscopy and Transmission Electron Microscopy of selected samples prepared with a Dual Beam microscope using a Focused Ion Beam. For the processing conditions used, the coatings showed larger exothermic crystallization peaks. The results of microhardness from coatings showed values of hardness over 700 HV.

中文翻译：

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使用激光熔覆的 Fe-Nb-B 粉末超细共晶涂层

摘要 本文提出了一种激光熔覆工艺，在定义了功率和扫描速度的AISI 1020钢基体上获得超细共晶Fe-Nb-B合金涂层。激光熔覆工艺可用作快速固化加工路线，以产生单个激光轨道和涂层（重叠轨道），其中预先放置的粉末沉积在低碳钢基材上，以便在涂层/基材之间获得最小的稀释。本研究旨在通过激光熔覆使用预先放置的粉末方法在 AISI 1020 钢基材上生产 Fe74.25Nb8.25B17.5 (at.%) 合金涂层，以研究涂层生产、稀释、微观结构和特性。最终目标是找到合适的加工参数范围，以获得具有高硬度和可能具有良好耐磨性的涂层。粉末、包覆层和涂层的微观结构和行为通过 X 射线衍射、差示扫描量热法、扫描电子显微镜和透射电子显微镜对使用聚焦离子束的双光束显微镜制备的选定样品进行检查。对于所使用的加工条件，涂层显示出较大的放热结晶峰。涂层的显微硬度结果显示硬度值超过 700 HV。使用聚焦离子束的双光束显微镜制备的选定样品的扫描电子显微镜和透射电子显微镜。对于所使用的加工条件，涂层显示出较大的放热结晶峰。涂层的显微硬度结果显示硬度值超过 700 HV。使用聚焦离子束的双光束显微镜制备的选定样品的扫描电子显微镜和透射电子显微镜。对于所使用的加工条件，涂层显示出较大的放热结晶峰。涂层的显微硬度结果显示硬度值超过 700 HV。