Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating
Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating
复制标题
DOI：
10.1016/j.apsusc.2016.11.176
复制
发表时间：
2017-02-28
影响因子：
6.7
通讯作者：
Wu, Yixiong
中科院分区：
文献类型：
--
作者：
Ye, Qingfeng;Feng, Kai;Wu, Yixiong
等摩尔CrMnFeCoNi高熵合金（HEA）是目前最引人注目的单相多元合金之一，具有良好的低温力学性能。然而，目前对CrMnFeCoNi热喷涂涂层的腐蚀行为研究还比较少。本文采用激光表面合金化方法制备了名义成分为CrMnFeCoNi的HEA涂层，并对其进行了详细研究。利用X射线衍射仪（XRD）、光学显微镜（OM）、扫描电镜（SEM）和能谱仪（EDS）分析了试样的显微结构和化学成分。采用动电位极化曲线和电化学阻抗谱（EIS）研究了该合金的腐蚀行为.涂层形成简单的FCC相，具有由富Fe/Co/Ni枝晶和富Mn/Ni枝晶间组成的相同的树枝状结构。均为3.5重量%在NaCl溶液和0.5M硫酸中，涂层的耐蚀性优于A36钢基体，甚至低于304不锈钢（304 SS）。EIS图加上拟合参数显示，自发的保护膜的形成和发展过程中浸泡在0.5 M硫酸。在48 h浸泡试验中，拟合的R-t值在24 h时达到最大值，表明钝化膜在24 h后开始破裂。在浸泡在0.5 M H2SO 4中的腐蚀表面上进行的EDS分析表明，腐蚀从贫Cr的枝晶间开始。(C)© 2016 Elsevier B. V.版权所有。
Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i(corr) than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R-t value reaches its maximum at 24h during a 48 h' immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H2SO4 reveals that corrosion starts from Cr-depleted interdendrites. (C) 2016 Elsevier B.V. All rights reserved.