|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||High Entropy Alloys IV
||A Statistical Study of the Potential-scan-rate and Al-content Dependent Metastable Pitting (Serration) Behavior of AlxFeCoCrNi High-entropy Alloys
||Yunzhu Shi, Bin Yang, Xie Xie, Zhi Tang, Karin A. Dahmen, Peter K. Liaw
|On-Site Speaker (Planned)
This study investigated the influence of the potential-scan-rate and Al-content on the corrosion behavior of AlxFeCoCrNi (x= 0.3, 0.5, and 0.7) alloys in 3.5 weight percent NaCl solution via scanning electron microscopy and electrochemical experiments. During the potentiodynamic polarization tests, current fluctuations (serrations) occurred in the passivation area, which was related to the formation and repassivation of metastable pitting before reaching the critical pitting potential (Ec). With increasing Al content and scan rate, both Ec and metastable pitting potential (Em) decreased due to the degraded passivation film caused by the increasing volume fraction of Cr-depleted BCC phase, which passivation film was preferentially attacked by Cl− ions, and insufficient oxidation film formation time. Furthermore, a mean-field theory (MFT) was successfully applied to predict a power-law distribution of current fluctuation amplitudes multiplied with an exponentially-decaying cutoff function depending on the experimentally-tunable parameters, in this case, the potential scan rate.
||Planned: A print-only volume