Environmental Degradation of Multiple Principal Component Materials: Aqueous Corrosion and Embrittlement I
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 8:00 AM
March 21, 2023
Room: Sapphire 410A
Location: Hilton

Session Chair: Wenjun Cai, Virginia Tech; Xiaoxiang Yu, Novelis Global Research Center


8:00 AM  
A High, Medium to Low Throughput Study of Aqueous Passivation in FeCoNi–(Crx–Aly) Alloys across Classical Cr Threshold Concentration: Debashish Sur1; William Blades2; Emily Holcombe3; Elaf Anber3; Lauren Walters4; Ben Redeman3; Brian DeCost5; Jean-Philippe Couzinie6; Howie Joress5; James Rondinelli4; Tyler McQueen3; Karl Sieradzki2; Mitra Taheri3; John Scully1; 1University of Virginia; 2Arizona State University; 3Johns Hopkins University; 4Northwestern University; 5National Institute of Standards and Technology; 6CNRS-UPEC
    FeCoNi-CrxAly alloys with x+y < 0.25 were studied with the goal of delineating the role of Al in long term passivation performance. A combinatorial thin film library with 177 different compositions was deposited and characterized through HTp XRF and synchrotron-XRD to obtain compositions and phases present in each individual alloy. Their aqueous passivation behavior was examined using a HTp scanning droplet cell in sulfuric acid by DC and AC electrochemical methods to define the best performing alloys. Bulk alloys containing Al and near Cr threshold were prepared based on the HTp screened compositions for further medium to high fidelity testing. Cr-Cr short range order was found via Neutron scattering PDF. XPS and batch ICP-OES measurements after long term exposure defined the fate of each element in terms of its role in the passivation process. A framework for understanding long term passivation in Al-Cr alloys was developed.

8:20 AM  
Cold Working Enhanced Thermal Stability of Native Oxide Solar Absorbers on FeMnNiAlCr High Entropy Alloys for Concentrated Solar Power System: Xiaoxue Gao1; Edwin Jiang1; Andrew Pike1; Ian Baker1; Geoffroy Hautier1; Jifeng Liu1; 1Dartmouth College
    Cost-effective FeMnNiAlCr high entropy alloys (HEAs) have shown excellent high-temperature mechanical and chemical properties, promising to serve as tubing materials for next generation concentrated solar power system (CSP). Furthermore, its native oxides, mostly composed of Mn2O3, synergistically function as a solar absorber with ~90% solar-to-thermal conversion efficiency. However, the huge and repetitively temperature change in day-night thermal cycles of CSP systems between ~750°C and ~25°C challenges the thermal stability of native oxide solar absorbers. In this paper, we significantly improve the thermal stability of native oxide on FeMnNiAlCr HEAs by cold working and partial recrystallization to optimize the microstructures against excessive oxidation. The native oxide could maintain its optical performance after >20 day-night thermal cycles, compared to <5 cycles for reference samples. This cold work effect can be explained by enhanced diffusion pathway density for high-quality alumina formation through microstructure engineering, which helps to establish and sustain the protective layer.

8:40 AM  Invited
Corrosion and Mechanical Behavior of High-Entropy Alloys: Michael Gao1; Alvaro Rodriguez1; Zongrui Pei1; Joseph Tylczak1; Paul Jablonski1; Martin Detrois1; Margaret Ziomek-Moroz1; Jeffrey Hawk1; 1National Energy Technology Laboratory
    Many high entropy alloys (HEAs) with the face-centered cubic structure are reported to have excellent ductility and corrosion resistance. In this talk, the corrosion behavior of select FCC HEAs in NaCl and NaCl+CO2 aqueous conditions at 25 and 40 degree Celsius will be presented. Their corrosion parameters (corrosion rate, current, etc.) are compared to those of commercial alloys (C-276, stainless steel 316L and Multimet). Electrochemical measurements can show additional corrosion characteristics. Potentiodynamic polarization measurements can indicate active, passive and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy elucidates the corrosion mechanism under studied conditions. The tensile behavior of these alloys at various temperatures are also reported. To elucidate the corrosion and mechanical behavior, the atomic structure, elastic properties, and stacking faults energies of these HEAs are predicted using density functional theory methods.

9:00 AM  Invited
Corrosion Behavior of High-Entropy Alloys: Lia Amalia1; Yunzhu Shi2; Rui Feng1; Yanfei Gao1; Peter Liaw1; 1University of Tennessee; 2University of Science and Technology Beijing
    Corrosion is a natural occurring process. A metal that is chemically unstable in a certain environment will degrade. To withstand a certain corrosive environment, a material needs to be specially designed so that the lifetime, reliability, and safety could be ensured. In recent years, the study of corrosion behavior of high-entropy alloys (HEAs) has been conducted extensively, since HEAs may contain a high content of passivity-inducing elements, such as chromium, nickel, molybdenum, aluminum, titanium, and others. The corrosion behavior has been investigated in high-pressure and high-temperature water, chloride-rich environments, and acid solutions. These investigations provided a new knowledge that each alloying element plays a significant role in the protective passive film formation. Other significant factors include processing methods, which would influence the microstructure of the HEAs, and thus, corrosion behavior. High-throughput corrosion experiments will be discussed. The corrosion behavior of HEAs will be compared to commercial alloys.

9:20 AM Break

9:35 AM  
Determining Elemental Distributions across Thin Corrosion Films on Multi-principal Element Alloys via Atom Probe Tomography: Elizabeth Kautz1; Angela Gerard2; Sten Lambeets1; Daniel Perea1; John Scully2; Daniel Schreiber1; 1Pacific Northwest National Laboratory; 2University of Virginia
    Atom probe tomography (APT) provides a unique, three-dimensional map of elemental distributions formed during oxidation and corrosion of multi-principal element alloys (MPEAs) with near-atomic resolution. While ex situ APT characterization is well-established for analyzing buried interfaces in materials, the similar analysis of nanoscale surface films formed during alloy passivation is extremely challenging. In this talk, we discuss sample preparation and general experimental approaches to leverage APT’s 3D imaging capabilities for analyzing thin passive films. Ex-situ sample capping strategies and quasi-in-situ APT experiments with passive films formed directly on APT needles will be contrasted. Observations of elemental segregation, partitioning, and kinetic trapping are discussed in the context of initial passive film formation on corrosion resistant non-equiatomic transition metal-based MPEAs and model binary alloys. Lastly we highlight ongoing challenges and opportunities for this experimental approach.

9:55 AM  
Influence of Hydrogen on the Low Cycle Fatigue Behavior of the Equiatomic CrMnFeCoNi High Entropy Alloy: Dayane Marques Oliveira1; Christopher San Marchi2; Easo George3; Jeffery Gibeling1; 1University of California, Davis; 2Sandia National Laboratories, Livermore; 3Oak Ridge National Laboratory
    True plastic strain-controlled low cycle fatigue (LCF) tests were performed on the CrMnFeCoNi high-entropy alloy in the non-charged and hydrogen-precharged (H-precharged) conditions. Internal hydrogen increases the cyclic strength of this alloy at all plastic strain amplitudes by enhancing the effective component of the flow stresses. These effective stresses are greater than back stresses for all tested conditions. Furthermore, the evolution of back stresses during LCF testing at different strain amplitudes is not influenced by the presence of hydrogen, suggesting that the dislocation structures are similar in non-charged and H-precharged conditions. Primary fatigue crack(s) initiate earlier in the H-precharged than in the non-charged condition, and the presence of hydrogen severely reduces the LCF lifetime of this alloy. Fracture surface observations reveal that, although plastic deformation processes are active in the H-precharged condition, hydrogen leads to intergranular failure in the CrMnFeCoNi alloy.

10:15 AM  
Understanding Elemental Effects on the Accelerated Corrosion of FeCrAl Alloy System in Steam Environments: Atharva Chikhalikar1; Indranil Roy1; Hamdy Abouelella1; Rajnikant Umretiya1; Andrew Hoffman1; Raul Rebak1; 1GE Research Center
    FeCrAl alloy systems are emerging as promising candidates to replace Zr-based nuclear fuel cladding materials due to their corrosion resistance in Loss of Coolant Action (LOCA) like scenarios. However, there is limited understanding of the elemental effects on the oxidation resistance of alloys in Boiling Water Reactor (BWR) conditions. Understanding the role of elements on the degradation mechanisms in both BWR and LOCA conditions is essential for developing next-generation Multiple Principal Component Alloys (MPCA). This work systematically explores the corrosion resistance of two FeCrAl alloys; Fe-21Cr and Fe-21Cr-5.5Al in the steam environment at 400 °C and 1200 °C. The samples were characterized upon exposure to identify the corrosion products and understand the corrosion mechanism under varying parameters. The results enhanced the understanding of the role of Al in affecting the corrosion resistance at both temperatures and provided implications for developing next-generation FeCrAl-based MPCA Fuel Claddings.