| TANG Yan-chuan,WANG You-xing,LIU De-jia,JIAO Hai-tao,HU Yong,TANG Xing-chang,ZHAO Long-zhi.Corrosion Behavior of Laser Deposited Non-equiatomic CoCrFeNiSi-(Al,Ti) HEA Coatings[J],52(9):377-387, 396 |
| Corrosion Behavior of Laser Deposited Non-equiatomic CoCrFeNiSi-(Al,Ti) HEA Coatings |
| Received:August 22, 2022 Revised:January 11, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.09.034 |
| KeyWord:laser deposition CoCrFeNi based HEAs Al Ti microstructure corrosion resistance |
| Author | Institution |
| TANG Yan-chuan |
School of Materials Science and Engineering, Nanchang , China;State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure, East China Jiaotong University, Nanchang , China |
| WANG You-xing |
State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure, East China Jiaotong University, Nanchang , China |
| LIU De-jia |
School of Materials Science and Engineering, Nanchang , China;School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
| JIAO Hai-tao |
School of Materials Science and Engineering, Nanchang , China;School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
| HU Yong |
School of Materials Science and Engineering, Nanchang , China;School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
| TANG Xing-chang |
State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou , China |
| ZHAO Long-zhi |
School of Materials Science and Engineering, Nanchang , China;School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
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| Abstract: |
| The laser deposited CoCrFeNi based high entropy alloy (HEA) coatings can possess better corrosion resistance than the austenitic and ferritic stainless steels, and are expected to be applied to the anticorrosive coating on the materials serving in the harsh environment, such as marine industry, petrochemical industry, aerospace, etc. As two commonly used elements for improving the corrosion resistance of CoCrFeNi based HEA coatings, the individual effect of Al or Ti element on the corrosion resistance of CoCrFeNi based HEA coatings has been well studied, but it is still lack of the research aiming at comparing which of these two elements has more significant effect on the coatings. This work aims to compare the effects of Al and Ti element on the corrosion behaviors of non-equiatomic CoCrFeNiSi-(Al,Ti) HEA coatings. The CoCrFeNi HEA, Al, Si, and Ti powder were used to prepare the mixture powder according to the composition of CoCrFeNiSi0.5, CoCrFeNiSi0.5Al0.5, CoCrFeNiSi0.5Ti0.5, and CoCrFeNiSi0.5Al0.5Ti0.5. The HEA coatings were prepared by a semiconductor laser (LDM-2500-60) with coaxial powder feeding method on the 316L substrates. The phase structure of the laser deposited coatings was analyzed by an X-ray diffractometer (XRD, D8 Advance, Bruker). The microstructure of the longitudinal section (plane perpendicular to the laser scanning direction) of the coatings was observed by an optical microscope (OM, Axio Vert.A1, Zeiss). The microstructure of the surface of the coatings before and after corrosion was studied by a field emission scanning electron microscope (FESEM, SU-8010, Hitachi), while the micro-area composition was analyzed by the supporting energy dispersive spectroscopy (EDS). The corrosion behaviors of the HEA coatings in 0.5 mol/L H2SO4 solution were studied by an electrochemical workstation (CS350, Wuhan Corrtest). The results indicated that the laser deposited CoCrFeNiSi0.5 HEA coatings were composed of face-centered cubic (FCC) phase. The major phase of CoCrFeNiSi0.5Al0.5 HEA coatings changed to body-centered cubic (BCC) phase and the Cr3Si phase distributed along the grain boundaries was established. The major phase of CoCrFeNiSi0.5Ti0.5 HEA coatings maintained FCC phase, but a large quantity of G phase (Ni16Ti6Si7) was formed in the interdendritic (ID) region and the long-strip Cr15Co9Si6 phase was formed in the dendritic (DR) region. The major phase of CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings was BCC phase and the content of G phase distributed in the ID region was much lower than that in CoCrFeNiSi0.5Ti0.5 HEA coatings. Furthermore, a large number of dispersed square nanoparticles were formed in the DR region. The corrosion resistance of laser deposited non- equiatomic CoCrFeNiSi-(Al,Ti) HEA coatings in 0.5 mol/L H2SO4 solution could be ordered as CoCrFeNiSi0.5Ti0.5> CoCrFeNiSi0.5Al0.5Ti0.5>CoCrFeNiSi0.5>CoCrFeNiSi0.5Al0.5. After immersion in the 0.5 mol/L H2SO4 solution, the CoCrFeNiSi0.5 HEA coatings exhibited relatively uniform corrosion and the CoCrFeNiSi0.5Al0.5 HEA coatings indicated severely intergranular corrosion. CoCrFeNiSi0.5Ti0.5 and CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings mainly presented pitting corrosion in the ID region, while the latter had a higher extent of pitting corrosion and the nanoparticles in the DR region fell off. In general, compared with Al element, Ti element can improve the corrosion resistance of laser deposited CoCrFeNi based HEA coatings more effectively in acidic solution environment, due to the better protective effect produced by the passivation film. This work can provide theoretical references and data supports for the research and development of HEA anticorrosive coatings serving in the harsh environment. |
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