Ce变质处理提高Fe-Cr-Ni中熵合金抗点蚀性的研究  

Pitting Corrosion Resistance Enhancement of Fe-Cr-Ni Medium Entropy Alloy by Ce Modification

作　　者：杜晓洁[1] 张威[2] 丁骁 贾玺泉 徐震霖 范光伟[2] 何宜柱[1] DU Xiao-jie;ZHANG Wei;DING Xiao;JIA Xi-quan;XU Zhen-lin;FAN Guang-wei;HE Yi-zhu(School of Materials Science and Engineering,Anhui University of Technology,Maanshan 243002,China;State KeyLaboratory of Advanced Stainless Steel Materials,Taiyuan Iron and Steel(Group)Co.,Ltd.,Taiyuan 030024,China)

机构地区：[1]安徽工业大学材料科学与工程学院,安徽马鞍山243002 [2]太原钢铁(集团)有限公司先进不锈钢材料国家重点实验室,太原030024

出　　处：《表面技术》2022年第3期117-127,共11页Surface Technology

基　　金：山西省科技重大专项资助项目(20181101016)。

摘　　要：目的 研究Ce变质处理提高Fe-Cr-Ni中熵合金在3.5%NaCl溶液中抗点蚀性的机理。方法通过动电位极化实验,分析Ca变质处理与Ce变质处理的Fe-Cr-Ni中熵合金的抗点蚀性。利用SEM和EDS等手段观察了经不同变质处理后合金中夹杂物的形貌和元素组成,并结合阻抗谱分析与XPS技术研究了Ce对钝化膜保护力的影响。结果经不同变质处理的Fe-Cr-Ni中熵合金中的夹杂物形态不同,Ca变质处理合金中夹杂物为CaO-Al_(2)O_(3)和CaS-Al_(2)O_(3)复合夹杂物。在腐蚀过程中,CaS优先溶解导致点蚀萌生。Ce变质处理合金中夹杂物是具有核壳结构的(Ce,Si)_(x)O_(y)-(Al,Mn)_(x)O_(y)稀土复合夹杂物,降低了点蚀敏感度,提高了抗点蚀性。在3.5%NaCl溶液中,Ca变质处理Fe-Cr-Ni中熵合金的腐蚀电流密度为3.108×10^(‒6)μA/cm^(2),Ce变质处理Fe-Cr-Ni中熵合金的腐蚀电流密度为4.883×10^(‒7)μA/cm^(2),其腐蚀电流密度降低了85%。Ca变质处理与Ce变质处理的Fe-Cr-Ni中熵合金的容抗弧均呈不完整的半圆状,钝化膜与基体间的电荷转移电阻分别为1.872×10^(5)Ω•cm^(2)和4.312×10^(5)Ω•cm^(2),Ce变质处理合金钝化膜中电荷转移电阻提高了1.3倍。稀土铈提高了钝化膜的Cr+Ni/Fe+Mn阳离子比,Ca变质处理与Ce变质处理的Fe-Cr-Ni中熵合金钝化膜的Cr+Ni/Fe+Mn阳离子分别为1.66和1.2。XPS分析结果同样表明,Ce变质处理Fe-Cr-Ni中熵合金钝化膜具有更好的保护性。结论和Ca变质处理Fe-Cr-Ni中熵合金相比,Ce变质处理合金具有更优异的抗点蚀性,这主要归因于稀土元素Ce的影响,一方面Ce使合金中的夹杂物改性,降低了点蚀敏感度;另一方面Ce增加了钝化膜的保护能力,提高了点蚀抗力。The paper aims to study the mechanism of improving the pitting resistance of Fe-Cr-Ni medium entropy alloy(MEA)in 3.5wt.%NaCl solution by Ce modification.The pitting resistance of Ce-modified and Ca-modified Fe-Cr-Ni MEA were analyzed by potentiometric polarization experiment.The morphology and element composition of inclusions in the alloy with different modification treatments were observed by SEM and EDS,and the effect of RE Ce on the protective force of passivation film was studied by impedance spectroscopy and XPS technique.The morphology of inclusion in Fe-Cr-Ni MEA with different modification treatments was not consistent.Inclusions in Ca-modified alloy could be divided into two categories which were CaO-Al_(2)O_(3) and CaS-Al_(2)O_(3) composite inclusions,and the preferential dissolution of CaS in the corrosion process lead to the initiation of pitting corrosion.The inclusions in Ce-modified Fe-Cr-Ni MEA were(Ce,Si)_(x)O_(y)-(Al,Mn)_(x)O_(y) rare earth composite inclusion with a core-shell structure,which reduced the pitting sensitivity and improved the pitting resistance.In 3.5wt.%NaCl solution,the corrosion current density of Ca modified Fe-Cr-Ni entropy alloy was 3.108×10^(‒6)μA/cm^(2),and the corrosion current density of Ce modified alloy was 4.883×10^(‒7)μA/cm^(2) which was reduced by 85%.The capacitive reactance arc of Ce-modified and Ca-modified Fe-Cr-Ni MEA showed an incomplete semicircircle shape.The charge transfer resistance between the passivation film and matrix was 1.872×10^(5)Ω•cm^(2) and 4.312×10^(5)Ω•cm^(2).The charge transfer resistance in the passivation film of the Ce-modified alloy increased by 1.3 times.RE Ce increased the Cr+Ni/Fe+Mn cation ratio of the passivated film,and the Cr+Ni/Fe+Mn cation ratio of Ce-modified and Ca-modified passivation films was 1.66 and 1.2,respectively.The result of XPS analysis also indicated that the passivation film of Fe-Cr-Ni MEA by Ce modification had better protection.Compared with Ca-modified Fe-Cr-Ni MEA,Ce-modified alloy has bette

关 键 词：稀土Ce Fe-Cr-Ni中熵合金 点蚀 夹杂物 核壳结构 钝化膜 

分 类 号：TG172[金属学及工艺—金属表面处理]