(大連理工大學(xué) 材料科學(xué)與工程學(xué)院，大連 116024)
摘 要: 研究CoCrFeNiTi0.5高熵合金在熔融Na2SO4-25%NaCl(質(zhì)量分?jǐn)?shù))中的腐蝕行為，應(yīng)用TGA獲得其在650和750 ℃空氣中的腐蝕動(dòng)力學(xué)曲線；采用XRD、SEM(EDS)和EPMA對(duì)腐蝕產(chǎn)物的截面形貌及元素分布進(jìn)行分析。結(jié)果表明：噴涂Na2SO4-25%NaCl的CoCrFeNiTi0.5高熵合金在650和750 ℃時(shí)的腐蝕動(dòng)力學(xué)曲線相似，呈“指數(shù)”增長(zhǎng)規(guī)律；腐蝕截面由含較多TiO2、部分Cr2O3以及微量尖晶石結(jié)構(gòu)氧化物構(gòu)成的氧化層與含孔隙且貧Cr和Ti、富Fe、Ni和Co的腐蝕影響區(qū)兩部分構(gòu)成；延長(zhǎng)腐蝕時(shí)間或提高腐蝕溫度后，氧化層破裂，與基體的結(jié)合程度顯著下降，發(fā)生嚴(yán)重剝離甚至脫落。分析認(rèn)為：CoCrFeNiTi0.5高熵合金在Na2SO4-25%NaCl中的高溫腐蝕歸因于氧化、硫化以及氯化的綜合作用。
關(guān)鍵字: 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
