Environmental Degradation of Multiple Principal Component Materials: Aqueous Corrosion and Embrittlement II
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Wenjun Cai, Virginia Polytechnic Institute and State University; XiaoXiang Yu, Novelis Inc.; Vilupanur Ravi, California State Polytechnic University Pomona; Christopher Weinberger, Colorado State University; Elizabeth Opila, University of Virginia; Bai Cui, University of Nebraska Lincoln; Mark Weaver, University of Alabama; Bronislava Gorr, Karlsruhe Institute of Technology (KIT); Gerald Frankel, Ohio State University; ShinYoung Kang, Lawrence Livermore National Laboratory; Srujan Rokkam, Advanced Cooling Technologies, Inc.

Tuesday 2:30 PM
March 21, 2023
Room: Sapphire 410A
Location: Hilton

Session Chair: Elizabeth Opila, University of Virginia; Wenjun Cai, Virginia Tech


2:30 PM  
Effect of Niobium Addition on the Passivity and Corrosion Resistance of TiHfZrNbx High-entropy Alloys in a Hanks’ Solution: Ayoub Tanji1; Xuesong Fan2; Ridwan Sakidja3; Peter K Liaw2; Hendra Hermawan1; 1University Laval; 2university of Tennessee; 3Missouri State University
    TiHfZrNbx is particularly made up of very passivating elements with very good biocompatibility, which can be interesting for permanent-stent material. This study showed that the TiHfZrNbx have a more corrosion-resistant character than the CP-Ti and Ti6Al4V. The corrosion resistance increases by increasing the Nb content, with a better repassivation behavior. A non-diffusional corrosion character was observed for the HEAs, with charge transfer and oxide film resistances greater than those of CP-Ti and Ti6Al4V, and they increase with increasing %Nb. The passive-film formed on HEAs specimens present an n-type semiconducting character composed mainly of TiO2, Nb2O5, ZrO2, and HfO2 oxides, with a decrease in donor densities with increasing the %Nb. The addition of 0.4% Nb (molar ratio) improved the corrosion resistance and surface characteristics of TiHfZrNbx by enhancing the passivity, associated with the decrease in the film defects and vacancies, as well as the charge transfer resistance of the oxide film.

2:50 PM  Invited
How Alloying Elements Affect Passivation and Dissolution in the NiCrFeCoMn System: New Insights Using Element-resolved Electrochemistry: Kevin Ogle1; Chenyang Xie1; Fan Sun1; Junsoo Han1; 1Chimie ParisTech, PSL University
    Understanding how different MPEA alloying elements react and interact during passivation and corrosion is essential for navigating the multidimensional composition space required for MPEA development. How do the electrochemical properties of the individual elements contribute to the overall kinetics of alloy dissolution and passive film formation and ultimately determine the corrosion resistance of the alloy? In this presentation, we will review recent efforts to address these questions using element resolved electrochemical methods (atomic spectroelectrochemistry). This method directly measures the elemental dissolution rates during electrochemical experiments and and elemental incorporation into the passive film may be determined indirectly by mass balance. To illustrate the methodology, we will focus on the formation of the Cr enriched passive film of the NiCrFeCoMn system in acid solution, the negative effect of Mn, with an emphasis on spontaneous (open circuit) passivation from either the active or the transpassive state.

3:10 PM  
Hydrogen Diffusion towards Notch Tips in Zirconium Alloys: Alireza Tondro1; Hamidreza Abdolvand1; 1University of Western Ontario
    Hydrogen embrittlement is an important degradation mechanism affecting the lifetime of the materials used in the core of nuclear reactors. The state diffusion of hydrogen atoms within the metal lattice are affected by the localized stresses that develop around service-induced flaws, which are significant in zirconium alloys with a high degree of elastic and plastic anisotropy. This study, using a coupled diffusion-crystal plasticity finite element approach, quantifies the contribution of texture and microstructure to the hydrogen diffusion towards microscale notches. The results suggest that material texture can significantly affect the distribution of hydrogen atoms, the location of maximum hydrostatic stress, and the location of maximum hydrogen concentration. It is also shown that as the notch tip becomes sharper, the effects of texture on hydrogen localization becomes less significant.

3:30 PM  
Effects of pH on the Corrosion and Tribocorrosion Behavior of Al0.1CrCoFeNi High Entropy Alloys in 0.6 M NaCl Solution: Jia Chen1; Zhengyu Zhang2; Jonathan Poplawsky3; Chang-Yu Hung2; Wenbo Wang2; Yi Yao4; Lin Li4; Hongliang Xin2; Wenjun Cai2; 1Virginia Polytechnic Institute; 2Virginia Polytechnic Institute and State University; 3Oak Ridge National Laboratory; 4University of Alabama
    High entropy alloys, also known as multi-principal element alloys (MPEAs) have grained increasing interests lately due to their exceptional mechanical, tribological and corrosion properties. The combination of these properties makes them ideal candidates for various applications under extreme conditions where surface stress and corrosive environments coexist. In the present study, the effects of pH on the tribocorrosion behavior of Al0.1CrCoFeNi MPEA was studied in simulated seawater under room temperature. The microstructure of as received and tribocorroded samples were characterized by scanning electron microscopy and x-ray diffraction. The element distribution and chemical state in worn and unworn areas were studied using energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The cross-sectional worn area was characterized by transmission electron microscopy. It was shown that this MPEA has the lowest corrosion resistance in alkaline solution, and the material loss increased with increasing pH, which is mainly dependent on the pH-dependent corrosion behavior of the alloy.

3:50 PM Break

4:05 PM  Invited
Passivation and Corrosion Resistance of Compositionally Complex Alloys: Effects of Cr: John Scully1; Angela Gerard1; Samuel Inman1; Debashish Sur1; Junsoo Han1; Elena Romanovskaia1; Jie Qi1; Mark Wischhusen1; Gerald Frankel2; Pin Lu3; James Saal3; SJ Poon1; Sean Agnew1; Elizabeth Kautz4; Daniel Schreiber4; Kevin Ogle5; 1University of Virginia; 2The Ohio State University; 3QuesTek Innovations LLC; 4Pacific Northwest National Laboratory; 5Chimie ParisTech, PSL Research University
    Compositionally complex and multi-principal element alloys (MPEAs) increase the degrees of freedom in the choice of alloying elements to produce either single phase solid solutions or complex multiphase microstructures. Mastery of element selection and alloy compositions holds the hope that novel combinations of properties, unobtainable in traditional alloys, are an outcome. From the aqueous corrosion perspective, optimization of phase stability, control of ordering, heterogeneities, passive film identity and protectiveness, as well as other attributes, often govern corrosion resistance. The quest for superior properties based on well-informed choice of alloying elements within certain specified compositions is of high interest. In this presentation, the effects of combinations of Cr, Cr-Al, and Cr-Al-Ti on passivation and protection in Cantor type alloys are discussed.

4:25 PM  
The Hydrogen Charging-induced Surface Degradation on High-entropy Alloys Studied via In-situ Techniques: Dong Wang1; Xu Lu1; Zhiming Li2; Roy Johnsen1; 1Norwegian University of Science and Technology; 2Max-Planck-Institut für Eisenforschung
    We investigated the effect of electrochemical hydrogen charging on the surface integrity of high-entropy alloys (HEAs). Two types of HEAs with stable (CoCrFeMnNi) and metastable (Fe50Mn30Co10Cr10C0.5) phases were tested by using in-situ electrochemical nanoindentation and scanning probe microscopy techniques in combination with advanced characterization and post analysis. After only hydrogen charging, surface slip line formation was observed on CoCrFeMnNi, while austenite to martensite transformation was detected on Fe50Mn30Co10Cr10C0.5. The hydrogen-induced internal stress is proposed to be responsible for the surface integrity change upon hydrogen charging, and this internal stress might be a potential driving force to the environmental failure of HEAs. It is necessary to consider these effects in future studies on hydrogen embrittlement and the design of hydrogen-tolerant alloys.