(大连理工大学 材料科学与工程学院，大连 116024)
摘 要: 研究CoCrFeNiTi0.5高熵合金在熔融Na2SO4-25%NaCl(质量分数)中的腐蚀行为，应用TGA获得其在650和750 ℃空气中的腐蚀动力学曲线；采用XRD、SEM(EDS)和EPMA对腐蚀产物的截面形貌及元素分布进行分析。结果表明：喷涂Na2SO4-25%NaCl的CoCrFeNiTi0.5高熵合金在650和750 ℃时的腐蚀动力学曲线相似，呈“指数”增长规律；腐蚀截面由含较多TiO2、部分Cr2O3以及微量尖晶石结构氧化物构成的氧化层与含孔隙且贫Cr和Ti、富Fe、Ni和Co的腐蚀影响区两部分构成；延长腐蚀时间或提高腐蚀温度后，氧化层破裂，与基体的结合程度显著下降，发生严重剥离甚至脱落。分析认为：CoCrFeNiTi0.5高熵合金在Na2SO4-25%NaCl中的高温腐蚀归因于氧化、硫化以及氯化的综合作用。
关键字: 高熵合金；硫化；氯化；氧化
（College of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China）
Abstract:The corrosion behavior of CoCrFeNiTi0.5 high entropy alloy (HEA) in molten Na2SO4-25%NaCl (mass fraction, %) was investigated. The corrosion kinetic curves at 650 and 750 ℃ were analyzed by TGA method. The scale structure and composition of the corroded products were examined by XRD, SEM equipped with EDS and EPMA. The results show that the corrosion kinetic curves of the CoCrFeNiTi0.5 alloy corroded at 650 and 750 ℃ are similar and follow exponent growth law. The cross-section consists of the oxide layers and the corrosion affected zones. The former is composed of mainly TiO2 and partly Cr2O3 as well as tiny compound oxides with spinel structure, and the latter with porous is depleted in Cr, Ti and rich in Fe, Ni and Co. Prolonging the exposure time or elevating the corrosion temperature, the oxide layer is broken and the adhesion with the matrix is worsened, and is peeled from the matrix. It is concluded that the corrosion behaviors of CoCrFeNiTi0.5 HEA in molten Na2SO4-25%NaCl is attributed to the interaction of oxidation, sulfidation and chlorination.
Key words: high entropy alloy (HEA); sulfidation; chlorination; oxidation
