Enhanced corrosion resistance of laser aided additive manufactured CoCrNi medium entropy alloys with oxide inclusion

• Published in: Corrosion science Vol. 195; p. 109965
• Main Authors: Weng, Fei, Chew, Youxiang, Ong, Wee Kit, Man, Yijun, Sui, Shang, Tan, Chaolin, Ng, Fern Lan, Goh, Min Hao, Bi, Guijun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.02.2022; Elsevier BV
• Subjects: Charge density; Charge transfer; Chromic hydroxide; CoCrNi; Corrosion behavior; Corrosion currents; Corrosion resistance; Electrochemical; Electrochemical corrosion; Laser aided additive manufacturing; Medium entropy alloy; Medium entropy alloys; Nonmetallic inclusions; Oxides; Stainless steels; Medium entropy alloy; Oxides; Laser aided additive manufacturing; Corrosion behavior; CoCrNi; Electrochemical
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2021.109965

The electrochemical corrosion behavior of laser aided additive manufactured (LAAMed) CoCrNi medium entropy alloys (MEAs) with different oxide inclusion levels was investigated in 3.5 wt% NaCl solution. Different from the 316 L stainless steel, no pitting appeared on the LAAMed CoCrNi within the test regime used in this study. The LAAMed sample with a higher oxide inclusion level demonstrated lower corrosion current density and higher charge transfer resistance, implying a more compact passive film. After holding in the solution at 0.2 VSCE for 30 mins, the passive films formed on the LAAMed CoCrNi MEAs have similar thickness and dominant constituent (i.e. Cr2O3 and Cr(OH)3). More oxides in the LAAMed CoCrNi MEA could facilitate the formation of a compact passive film, which leads to superior corrosion resistance. [Display omitted] •CoCrNi medium entropy alloys with different oxide level were fabricated by LAAM.•No pitting was observed from the potentiodynamic scan curves in the LAAMed CoCrNi.•The LAAMed CoCrNi with more in situ oxides showed superior corrosion resistance.•Selective corrosion along the molten pool and grain boundaries was illustrated.