About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
|
Symposium
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Environmental Degradation of Multiple Principal Component Materials
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Presentation Title |
Impaired Repassivation Kinetics of Multi-principal Element Alloy Surfaces Caused by Selective Oxidation and Nickel Enrichment |
Author(s) |
Jia Chen, Zhengyu Zhang, Wenjun Cai |
On-Site Speaker (Planned) |
Wenjun Cai |
Abstract Scope |
In this talk, we demonstrate the hindrance of repassivation in CrCoFeNi immersed in a sodium chloride solution with acidic to neutral pH levels. The hindrance is attributed to the creation of a subsurface layer enriched in nickel, resulting from selective oxidation and dissolution of various principal elements. However, this hindrance can be completely reversed at a basic pH, where the oxidation of all principal elements takes place. To unravel the structural underpinnings of the pH-dependent repassivation mechanisms, we employ a combination of surface analysis techniques and density functional theory calculations. Our findings reveal that the selective oxidation of chromium, cobalt, and iron in mildly acidic to neutral solutions alters the alloy's surface composition, causing a significant enrichment of nickel compared to the bulk. Consequently, the altered surface composition exhibits diminished repassivation capability due to the elevated electron work function and reduced surface reactivity resulting from the higher nickel concentration. |
Proceedings Inclusion? |
Planned: |
Keywords |
High-Entropy Alloys, Environmental Effects, Characterization |