L21-strengthened face-centered cubic high-entropy alloy with well pitting resistance

• Published in: Corrosion science 2023-05, Vol.215, p.111043, Article 111043
• Main Authors: Wei, Liang, Qin, Wei-Min, Chen, Jing-Yao, Lei, Wen-Xin, Xi, Jin-Yang
• Format: Article
• Language: English
• Subjects: High-entropy alloy; Micro-galvanic corrosion; Passive film; Pitting resistance; SKPFM
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2023.111043

Effect of phase structure and composition on the passive film properties and pitting behavior of L21-strengthened (CoCrFeNi)86Al7Ti7 high-entropy alloy (HEA) in 3.5 wt.% NaCl was investigated. Results shown that the bilayer amorphous passive film enriched in Cr-, Fe-oxides/hydroxides on (Fe, Cr)-rich FCC phase and that enriched in Ti-, Ni-oxides on (Ni, Al, Ti)-rich L21 phase both contributed to the well pitting resistance. There was a micro-galvanic corrosion effect between FCC phase (cathode) and L21 phase (anode), which in synergy with Cl- broken the passive film on L21 phase at two-phase interface and resulted in pitting nucleation. •Pitting behavior of L21-strengthened (CoCrFeNi)86Al7Ti7 HEA in NaCl was studied.•Well pitting resistance resulted from the bilayer amorphous passive film.•Passive film on FCC phase was better protective than that on L21 phase.•There was a MGC effect between FCC phase (cathode) and L21 phase (anode).•Synergy of MGC and Cl- caused pitting to nucleate on L21 phase at FCC/L21 interface.