摘要:
本文采用放电等离子烧结技术（Spark Plasma Sintering,简称SPS）制备了Fe50Mn30Co10Cr10-xNbC(x = 0, 2, 5, and 10 wt.%)高熵合金复合材料，并利用光学显微镜、X射线衍射仪、扫描电镜、显微硬度计和电化学工作站等手段分析了其微观组织、硬度及耐腐蚀性能。研究结果表明：合金在SPS烧结过程中，石墨烯垫片中的碳元素会扩散到Fe50Mn30Co10Cr10高熵合金基体中，抑制其密排六方（HCP）相形成，使其由单一面心立方结构（FCC）构成。此外，扩散的碳与基体的合金中Fe，Co及Cr会在晶界处形成M23C6（（Fe，Co，Mn，Cr）23C6）的化合物。NbC的添加增加了形核质点的数量，细化了晶粒；随着NbC含量的增加，硬度得到了明显的提升，含有10 wt.% NbC的样品硬度值最高，为HV 463；耐磨性先升高后降低，其中加入2 wt.% NbC的高熵合金耐磨性最好，磨损量低至0.2479 mg；耐腐蚀性先变好后变差，极化曲线与阻抗谱的曲线表明添加5 wt.% NbC的样品耐腐蚀性更优。耐腐蚀性能与晶界的化合物组成及分布密切相关，当添加少量的NbC时，抑制了元素Cr的晶界析出，提升了腐蚀抵抗力；然而随着粗大的NbC颗粒在晶界上析出的连续性增强和富Cr相碳化物含量的增多，其腐蚀性能迅速的恶化。
Abstract:
In this paper, Fe50Mn30Co10Cr10-xNbC (x = 0, 2, 5, and 10 wt.%) high-entropy alloy composites were prepared by Spark Plasma Sintering (SPS) and analyzed by optical microscopy, X-ray diffractometer, scanning electron microscope, microhardness tester and electrochemical workstation. The microstructure, hardness and corrosion resistance were analyzed using optical microscopy, X-ray diffraction, scanning electron microscopy, microhardness tester and electrochemical workstation. The results show that the carbon in the graphene spacer diffuses into the Fe50Mn30Co10Cr10 high-entropy alloy matrix during the SPS sintering process, which inhibits the formation of the dense hexagonal (HCP) phase and makes it consist of a single-sided centered cubic structure (FCC). In addition, the diffused carbon forms a compound of M23C6 ((Fe, Co, Mn, Cr)23C6) at the grain boundaries with Fe, Co and Cr in the alloy of the matrix. the addition of NbC increases the number of nucleation plasmas and refines the grains; the hardness is significantly increased with the increase of NbC content, with the highest value of HV 463 for the sample containing 10 wt.% NbC; The wear resistance first increased and then decreased, where the high entropy alloy with 2 wt.% NbC added had the best wear resistance with a low wear amount of 0.2479 mg; the corrosion resistance first became better and then worse, and the curves of polarization curves and impedance spectra showed that the samples with 5 wt.% NbC added had better corrosion resistance. The corrosion resistance is closely related to the composition and distribution of the compounds at the grain boundaries. When a small amount of NbC is added, the grain boundary precipitation of elemental Cr is suppressed and the corrosion resistance is improved; however, with the enhancement of the continuity of coarse NbC particles precipitating on the grain boundaries and the increase of the carbide content of Cr-rich phase, the corrosion resistance deteriorates rapidly.
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