摘要
利用循环极化曲线、激光共聚焦扫描显微镜(LSCM)、SEM和XPS等测试方法研究了Mo元素及热处理对Ni2CrFeMox高熵合金在3.5%NaCl (质量分数)溶液中耐蚀性能的影响。结果表明,铸态Ni2CrFeMox高熵合金的耐蚀性能明显高于316L不锈钢,其中Ni2CrFeMo0.2合金具有最小的维钝电流密度和腐蚀电流密度,耐蚀性能最好。过量Mo元素导致合金中析出σ相,发生电偶腐蚀,降低合金的耐蚀性能。固溶处理后,σ相的溶解及元素分布的均匀化减弱了电偶腐蚀的发生,耐蚀性能明显提高。
As a new alloy design concept, the high-entropy alloy(HEA) and the formation of simple solid solution introduce excellent properties such as high hardness, high strength and corrosion resistance. Investigations have shown that the single solid solution CrCoFeNi alloy possesses good corrosion resistance. The addition of Mo is beneficial to the corrosion resistance of the HEAs for potential industrial applications in 3.5%NaCl(mass fraction) simulating seawater type environments. The major effect of Mo is to promote the pitting potential of the alloy and inhibit the dissolution of the passivation film by forming and retaining molybdenum oxyhydroxide or molybdates(MoO42-). Considering that the cost of pure Co is higher, Ni and Co elements have similar atomic size and valence electron concentration, and the corrosion resistance of pure Ni is higher than that of pure Co, Ni2CrFeMox HEA was designed by replacing Co element with Ni element in CoCrFeNiMoxHEA. As the Mo content increases in the Ni2CrFeMox HEAs, the interdendrite is a Cr and Mo rich σ phase, and the dendrite is a Cr and Mo depleted fcc phase. The potential difference between interdendrites and dendrites leads to galvanic corrosion, which accelerates the localized corrosion of alloys. Here, a solution heat treatment process is selected to reduce the precipitation phase and improve the corrosion resistance of the alloy. The effects of Mo element and heat treatment on the corrosion resistance of Ni2CrFeMox HEA in 3.5%NaCl solution were tested. The results show that the corrosion resistance of as-cast Ni2CrFeMox HEA is obviously higher than that of 316 L stainless steel. The Ni2CrFeMo0.2 alloy has the best corrosion resistance because of its minimum dimensional passive current density and corrosion current density. However, the addition of excessive Mo leads to the precipitation ofσ phase and galvanic corrosion, which reduces the corrosion resistance of the alloy. After solution treatment, the uniformity of alloy structure and element distribution weakens gal
作者
魏琳
王志军
吴庆峰
尚旭亮
李俊杰
王锦程
WEI Lin;WANG Zhijun l;WU Qingfeng;SHANG Xuliang;LI Junjie;WANG Jincheng(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China2.Citic Daika Co.,Ltd.,Qinhuangdao 066011,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第7期840-848,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51471133和51771149~~
关键词
Mo元素
高熵合金
固溶处理
耐蚀性能
Mo element
high entropy alloy
solution treatment
corrosion resistance
