HEA 2023: Oxidation and Corrosion of HEAs II
Program Organizers: Andrew Detor, DARPA/DSO; Amy Clarke, Los Alamos National Laboratory
Tuesday 9:00 AM
November 14, 2023
Room: Riverboat
Location: Omni William Penn
Session Chair: Elizabeth Opila, University of Virginia
9:00 AM Introductory Comments
9:05 AM Invited
Understanding Oxidation in High Entropy Alloys: Todd Butler1; Byron McArthur1; Samuel Kuhr1; Oleg Senkov1; Satish Rao1; Daniel Miracle1; 1Air Force Research Laboratory
High entropy alloys are innovative materials that show great promise for future use in high temperature applications. Their compositional complexity offers extended ability to promote enhanced capability across mechanical, thermal and environmental domains, while reducing the barrier to balancing multiple performance factors. Oxidation resistance is of particular interest, especially in the refractory domain, due to the formation of more favorable complex oxides that do not readily form in dilute alloys. This talk will highlight the oxidation behaviors of both 3d-transition metal-based and refractory high entropy alloys. Each domain will be discussed relative to classical oxidation mechanisms and associated models. Key technical gaps and future opportunities will be addressed.
9:35 AM
Tuning Composition via Computational Thermodynamics to Improve Corrosion Resistance of CoCrFeMnNi Multi-principal Element Alloys: David Silva1; Guilherme Koga2; Valmor Mastelaro3; Michael Kaufman1; Amy Clarke1; Francisco Coury2; Claudemiro Bolfarini2; 1Colorado School of Mines; 2Federal University of Sao Carlos; 3University of São Paulo
A computational thermodynamic approach has been employed to design non-equimolar CoCrFeMnNi multi-principal element alloys (MPEAs) with systematically varied compositions (Co((80-X)/2)Cr((80-X)/2)FeXMn10Ni10 with x = 30, 40 and 50) and enhanced corrosion behavior. MPEAs were successfully designed, synthesized and confirmed to possess a single-phase FCC structure. This work focuses on detailed analysis of the passivation film characteristics of these newly developed, non-equimolar MPEAs in two different electrolytes, i.e., 0.6 M NaCl and 0.5 M H2SO4 solutions, referred to as salt and acid solution environments, respectively. The characteristics of the passivation films were assessed using a potentiodynamic polarization test, immersion tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). In both electrolytes, the corrosion resistance of the three non-equimolar MPEAs was improved over that of the equimolar alloy. The present work reveals a way to increase corrosion resistance by tuning the composition via computational thermodynamics.
9:55 AM
A High Throughput to High Fidelity Study of Aqueous Passivation in [FeCoNi]CrxAly Alloys Across Classical Cr Threshold Concentration: Debashish Sur1; Emily Holcombe2; William Blades3; Howie Joress4; Jason Hattrick-Simpers5; Ben Redeman2; Tyrell McQueen2; Karl Sieradzki3; Mitra Taheri2; John Scully1; 1University of Virginia; 2Johns Hopkins University; 3Arizona State Univeristy; 4National Institute of Standards and Technology; 5University of Toronto
FeCoNiCrxAly alloys with x+y < 0.25 (at.%) 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 x-ray fluorescence and synchrotron x-ray diffraction to obtain compositions and phases present in each individual alloy. Their aqueous passivation behavior was examined using a scanning droplet cell in sulfuric acid by DC and AC electrochemical methods to identify the best-performing alloys. Bulk alloys containing Al and near the classical threshold of 12 at% Cr were prepared based on the thin-film screened compositions for further analysis. Passive film formation and growth behaviors were characterized using electrochemical techniques and x-ray photoelectron spectroscopy. An Al-Cr synergy was found to significantly improve corrosion performance. The passivation and corrosion protection behavior of Al-Cr alloys was investigated in chloride-free and chloride-containing environments.
10:15 AM Cancelled
Development of Innovative Structural Materials from High Entropy Alloys Obtained by a Hybrid Powder/Wire Additive Manufacturing Process: Ayse Uyanik1; Caroline Toffolon2; Laure Martinelli2; Wilfried Pacquentin3; Hicham Maskrot1; 1Université Paris-Saclay, CEA, Service de Recherche en Matériaux et procédés Avancés (SRMA); 2Université Paris-Saclay, CEA, Service de Recherche en Corrosion et Comportement de Matériaux (S2CM); 3Université Paris-Saclay, CEA, Service de Physico-Chimie (SPC)
Owing to the vast compositional space, high entropy alloys (HEAs) open a new path in the development of new materials for molten salt reactors. In this work, high-throughput screening route are used to target compositions with the desired microstructural characteristics via numerical design tools using Thermo-calc and the TCHEA5 thermodynamic database in order, to produce alloys using laser additive manufacturing technologies (Direct Energy Deposition process and a hybrid powder/wire laser innovative process). Once fabricated, the corrosion resistance of these alloys has been tested in a salt molten environment.The microstructural characterisations by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) has allowed to suggest interesting alloy compositions for the targeted application.
10:35 AM Break
10:55 AM
High-temperature Oxidation Behavior of Refractory Complex Concentrated Alloys in Ta-Nb-Cr-Ti-Al system: Willian Pasini1; Filip Baciak1; Aleksandra Bętkowska1; Piotr Kupczyk2; Dorota Wilk-Kołodziejczyk1; Filip Kateusz1; Wojciech Polkowski1; 1Krakow Institute of Technololgy; 2AGH University of Krakow
Refractory Complex Concentrated Alloys (RCCAs) are promising structural candidates to surpass Ni superalloys in high-temperature environments. However, the oxidation resistance of refractory metal-based alloys represents one of their major drawbacks. Recently, a novel approach to providing inherent protection for RCCA was proposed based on the alloying of Ta and Cr to produce CrTaO4 on a Ta-Mo-Cr-Ti-Al system. Nevertheless, substantial Cr and Ta additions cause the precipitation of the brittle intermetallic Laves phase. Through the calculation of semi-empirical parameters and Calphad calculations, this work explores and designs new compositions of RCCAs with varied ratios of Ta and Cr, attempting to control the Laves phase formation. Prediction and validation of oxidation behavior were performed by artificial neural network models and 24 h long TGA tests at 1300°C in synthetic air (80/20 N2/O2 by volume) to reveal initial oxidation kinetics and short-term high-temperature degradation performance of news RCCA alloys.
11:15 AM
Lateral Variation in Multi-phase HEA Passive Films: Implications for Corrosion Resistant Alloy Design: Samuel Inman1; Peter Connors1; Mark Wischhusen1; Diego Ibarra Hoyos1; Joseph Poon1; Sean Agnew1; John Scully1; 1University of Virginia
HEAs allow for new strategies to target passivity and resistance to aqueous corrosion. The improved the compositional homogeneity can promote the formation long-range ordered or disordered solid solution oxides between multiple passivating elements. However, formation of such species can be hindered by elemental partitioning from second phase. While previous work has shown depletion of passivating elements can promote localized corrosion, little work has been done to evaluate the effects of microstructural partitioning on local and global passive film chemistry. This work evaluates corrosion behavior and lateral variation the dual-phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 passive film. Two distinct compositions are formed with defined lateral bounds matching the bulk microstructure. Thus, controlling microstructural partitioning and interface engineering may be effectively utilized as a tool to alter passive film chemistry, and by extension corrosion performance. The findings are discussed with respect to the lightweight low-cost Al-Cr-Fe-Mn-Mo-Ni-Ti system and extended to general corrosion resistant CCA design principals.
11:35 AM
Mechanical, Corrosion Properties and Industrial Application of CoCrFeNiTi-based Multiprincipal Element Alloys Achieved by a Combination of Additive Manufacturing and Heat Treatment: Fujieda Tadashi1; Hiroki Sugawara1; Toshimi Miyagi1; Yuzo Daigo1; Kousuke Kuwabara1; Hiroshi Shiratori2; 1Proterial, Ltd; 2Hitachi, Ltd
CoCrFeNiTi-based multiprincipal element alloys (MPEAs) are proposed to meet the demands of high mechanical strength and corrosion resistance in additively manufactured products. First, the effectiveness of applying L-PBF to this MPEA was compared with that of using EB-PBF. The higher solidification rate during L-PBF promoted a fine uniform microstructure with no coarse precipitates, which led to superior tensile properties and a higher pitting potential in comparison to the EB-PBF specimens. In addition, the ultimate tensile strength of the L-PBF specimens increased over 1500 MPa and the corrosion rates in boiling 10% H2SO4 decreased to less than 1mm year by the microstructure control in the solution and aging heat treatments. Furthermore, the higher cobalt and chromium content of the proposed CoCrFeNiTi-based MPEA demonstrated their effectiveness in retarding acid corrosion. We will also report the applicability of the die steel coated this MPEA by L-DED to the hot forging mold.
11:55 AM
Refractory Element Free High Entropy Alloy With Exceptional Oxidation Resistance at Elevated Temperature: Pooja Jangra1; Aditya Balpande1; Ananya Chattree1; Akshit Dutta1; Saurabh Nene1; 1Indian Institute of Technology Jodhpur
High temperature oxidation of metallic alloys is inevitable during service. However, aerospace and aeronautical components demand delayed oxidation kinetics of alloys used in them to avoid their sudden failures during service. In line of that, here we present a next generation Ni-Co-V-Fe-Cr-Si containing high entropy alloy (OR-HEA) displaying very sluggish oxidation kinetics after exposing to 1050 C up to 100 hrs in muffle furnace atmosphere. The weight gain appears to saturate at 10 hrs of exposure and showed negligible increase in weight even after 100 hrs of exposure to 1050 C. The resultant high temperature oxidation behavior is exceptional when compared with the conventional IN-718 super alloy and much better than the newly designed refractory containing HEAs in similar temperature range and corrosive atmospheres. Thus, development of OR-HEA is not only providing cost friendly but also weight-effective pathway for designing high temperature alloys of future.