HEA 2023: Poster Session
Program Organizers: Andrew Detor, DARPA/DSO; Amy Clarke, Los Alamos National Laboratory
Monday 5:30 PM
November 13, 2023
Room: Sternwheeler
Location: Omni William Penn
Contender High-entropy Alloy Coatings to Superalloy 720 for Hot-forging Dies: Tanjore Jayaraman1; Ramachandra Canumalla2; 1United States Air Force Academy; 2Weldaloy Specialty Forgings
Superalloy 720 is ubiquitous to a myriad of high-temperature applications, including weldoverlay coatings for hot-forging dies. Currently, high-entropy alloys, having a unique combination of ambient and elevated temperature properties, appear as potential competitors to superalloy 720 as coatings for conventional hot-forging die materials, e.g., Uddeholm Dievar or H13. We analyzed the refractory high-entropy alloys (RHEAs) available in the current literature by decision science-driven techniques, including multiple-attribute decision making (MADM), for sorting and ranking the RHEAs. The ranks assigned by several MADMs, viz. WEDBA (weighted Euclidean distance-based approach), ROVM (range of value method), ARAS (additive ratio assessment), etc., were consistent. Principal component analysis (PCA) consolidated the ranks, while hierarchical clustering (HC) discerned the similarities among the alloys. The investigation identified contender RHEAs having properties superior to superalloy 720, revealed their potential as coatings for hot-forging dies, and suggested directives for further development.
Design of High Entropy Superalloy FeNiCrCoAl Using Molecular Dynamics, Computational Thermodynamics and Machine Learning: Tria Achmad1; Fauzi Sukma1; Putri Wibowo1; 1Bandung Institute of Technology
The development of High Entropy Superalloy (HESA) with superior mechanical properties and affordable raw material raises the possibility of replacing superalloys. Designing a HESA frequently involves expensive and time-consuming processes of experimental. Even with the growth of computational studies, it still complicated to model multicomponent alloy systems. This study focuses on the compositional design simulation of HESA FeNiCrCoAl on lattice parameters, stacking fault energy (SFE), and compression strength using molecular dynamics (MD). We also propose a new approach to predict SFE using extensive data analysis by leveraging machine learning and computational thermodynamics. Then it is possible to explore the high-dimensional composition space much more efficiently. Increasing Al, Cr, and Co will decrease the SFE, while increasing Ni will increase the SFE. An optimal design guide for achieving desired SFE values: Ni (18-25 at%), Cr (24-30 at%), Al (5-15 at%), Co (20-35 at%), and Fe (20-35 at%). This work provides valuable insights into HESA mechanical behavior to improve creep resistance.
Formation and Physical Properties of New Superconducting High-entropy Alloys Prepared by Mechanical Alloying: Rafal Idczak1; Piotr Sobota1; Adam Pikul2; 1Institute of Experimental Physics, University of Wroclaw; 2Institute of Low Temperature and Structural Reaseach, Polish Academy of Sciences
In 2014, the first high-entropy alloy (HEA) superconductor, consisting primarily of 4d and 5d series elements, was found [1], revealing a new facet of the capabilities. A variety of studies have been performed on HEA superconductors since that time, to designate their potential for practical applications. Up to the present time, HEA superconductors are fabricated primarily through high-temperature arc-melting technique. A promising alternative for this method is mechanical alloying (MA). MA is a solid-state powder-processing technique involving repeated cold welding, fracturing, and re-welding of powder particles in a high-energy ball mill [2]. Physical properties of new superconducting HEAs prepared by MA will be presented. In particular, powders quality were verified by XRD and SEM. Critical superconducting parameters were determined from magnetization, electrical resistivity and specific heat data. [1] - P. Koželj et al., PRL (2014) 113.[2] - C. Suryanarayana, Progress in Materials Science 46 (2001) 1-184.
Influence of Mo on Low Temperature Tensile Properties of As-cast CrFeCoNi-Mo High Entropy Alloys: Toru Maruyama1; Mei Fukuzawa1; 1Kansai University
Annealed CoCrFeNi-Mo alloys show high tensile strength and no serious embrittlement occurred, although precipitation of the sigma phases, which are of concern for brittleness. However, tensile properties of as-cast CoCrFeNi-Mo alloys are currently not perfectly clarified, especially at low temperatures.Tensile tests of as-cast CoCrFeNi-Mo alloys (Mo at 4.9, 7.5, and 9.0 at%) were performed at room temperature and liquid nitrogen temperature. The as-cast specimens showed ruptured before plastic deformation occurred for the 7.5 at% Mo and 9.0 at% Mo alloys at both room temperature and liquid nitrogen temperature. These ultimate tensile strength were about 300 MPa. The 4.9at%Mo specimens at room temperature showed tensile strength of 645 MPa and elongation of 36.2%, and tensile strength of 934 MPa and elongation of 21.2% at liquid nitrogen temperature, suggesting that the high ductility at liquid nitrogen temperature was due to twin-induced plasticity.
Predicting Properties of High Entropy Carbides from their Respective Binaries: Mina Lim1; 1Gordon College
High Entropy Carbides (HECs) have been predicted the selection of candidate compositions with the phase stability from an entropy-forming-ability (EFA) descriptor from first principle. Using Density Functional Theory calculations, we address two questions: (1) to what degree can the properties of high entropy carbides created by equi-molar combinations of five of the set of eight refractory metals Hf, Nb, Mo, Ta, Ti, V, W, and Zr be predicted from their respective binaries compounds, and (2) can empirical relationships from properties of the binary compounds be used to predict phase stability for these materials. For the former question, it is found that lattice constant, binding energy and bulk modulus are well approximated by binary carbide averages. To address the second question, it is found that there is a correlation between EFA and the standard deviation of the distribution of bulk moduli of the constituent binaries.
Property and Microstructure Evaluation of Directed Energy Deposition High Entropy Alloys and Functionally Graded Materials: Yogesh Singla1; Luis Nunez III2; Calvin Downey2; Isabella Rooyen3; Michael Maughan1; 1University of Idaho; 2Idaho National Laboratory; 3Pacific Northwest National Laboratory
The present work investigates the mechanical and microstructural properties of high entropy alloys (HEAs) and functionally graded materials (FGMs) manufactured with SS316L substrates using powder blown directed energy deposition. The HEAs and FGMs contain a mixture of commercially available IN718, SS316L and 70Co30Cr and the effect of compositional variation on hardness was studied using nanoindentation. Optical microscopy revealed the inclusion of unsintered particles and porosity. EDS analysis confirmed that unsintered particles consist of CoCr. Optical microscopy also showed that the layers are mechanically and metallurgically well bonded to each other. The samples were primarily crack-free, however, micro-cracks were observed in one of the FGM samples. Nanoindentation results from 1000 indents on each sample indicated that HEA has overall higher hardness compared to FGMs. In the FGMs a decrease in hardness was observed with the decrease of CoCr percentage.
Unraveling the mechanisms of stability in CoxMo70-xFe10Ni10Cu10 high entropy alloys via physically interpretable graph neural networks: James Chapman1; Miguel Tenorio1; 1Boston University
In recent years high entropy alloys (HEA) have become a topic of significant interest due to their combinatorial nature, showing promise for hypersonics and catalysts. In particular, the HEA system CoxMo70-xFe10Ni10Cu10 has been studied experimentally and computationally due to its reported superiority as a catalyst for ammonia decomposition. However, such catalytic reactions take place at elevated temperatures, leading to potential HEA instability and eventual phase separation at catalytically active temperatures. To this end, we combine density functional theory (DFT) calculations of mixing free energies, that include mixing and vibrational entropy terms, with physics-inspired graph neural networks (GNN) and consider binary (A ↔ B + C), ternary and quaternary decomposition routes. We show that by learning the mixing free energy with our GNN framework we can rank geometric and chemical HEA features to better understand which features are more important than others at stabilizing HEA stability at catalytically active temperatures.
Oxygen Reduction Reaction on Pt- non PGM Transition Metal High Entropy Alloy Surface: Single Crystal Model Catalyst Study: Toshimasa Wadayama1; 1TOHOKU University
Head-entropy alloys (HEA) are known as unique materials, exhibiting high mechanical strength and structural stability at high temperatures, anti-corrosion etc. Such unique properties have attracted much attention in the field of electrocatalysis, as the reduced free energy (ΔG) of HEAs should stabilize the topmost surface microstructures and thus increase the catalyst surface durability. However, at present, no study has been made on the correlations between HEAs electrocatalytic properties and lattice stacking structures, atomic-level distributions of constituent elements in the surface vicinity. In this study, we synthesized Pt-HEA(hkl) (hkl = 111, 110, 100) model catalyst surfaces by vacuum-deposition of a "Cantor alloy" (Cr-Mn-Fe-Co-Ni), followed by Pt layers on Pt single-crystal substrates in ultra-high vacuum (<10-7 Pa). Then, we evaluated ORR properties of the Pt-HEA(hkl) surfaces and discuss the correlation between the topmost surface micro-structures and electrocatalytic properties of the Pt-HEA.This study was supported by NEDO of Japan, JSPS KAKENHI (JP21H01645).
Manganese-based A-site High-entropy Perovskite Oxides for Solar Thermochemical Hydrogen Production: Xingbo Liu1; Cijie Liu1; Dawei Zhang2; Wei Li1; Jamie Trindell3; Keith King3; Sean Bishop3; Joshua Sugar3; Anthony McDaniel3; Andrew Smith3; Peter Salinas3; Eric Coker3; Arielle Clauser3; Joerg Neuefeind4; Jingjing Yang2; Hector De Santiago1; Liang Ma1; Yi Wang1; Qiang Wang1; Wenyuan Li1; Qingsong Wang5; Qingyuan Li1; Hanchen Tian1; Ha Ngoc Ngan Tran1; Xuemei Li1; Boyuan Xu6; Brandon Robinson1; Angela Deibel1; Gregory Collins1; Nhat Anh Thi Thieu1; Jianli Hu1; Yue Qi6; Jian Luo2; 1West Virginia University; 2University of California San Diego; 3Sandia National Laboratories; 4Oak Ridge National Laboratory; 5University of Bayreuth; 6Brown University
High-entropy perovskite oxides (HEPO) have been studied as a new family of redox oxides for solar thermochemical hydrogen (STCH) production owing to their favorable thermodynamic properties. Here, we report a strategy of introducing A-site HEPO, (La1/6Pr1/6Nd1/6Gd1/6Sr1/6Ba1/6)MnO3 (LPNGSB_Mn), which shows desirable thermodynamic and kinetics properties, and excellent cycling durability. LPNGSB_Mn exhibits enhanced hydrogen production (~100 mmol moloxide–1) compared to LSM (~68) in 1-hour redox duration and high STCH and phase stability for 50 cycles. LPNGSB_Mn possesses moderate reduction enthalpy reduction (260–286 kJ (mol-O)−1), high reduction entropy (130–164 J (mol-O)−1 K–1), and fast surface oxygen exchange kinetics. All A-site cations do not show observable valence changes during the redox processes; however, STCH production correlates with the number of equimolarly mixed A-site elements. This research suggests a new A-site mixing strategy and a new class of A-site high-entropy perovskite oxides with a vast compositional space for tailoring properties for STCH.
Cancelled
Unleashing the Power of Machine Learning for High-Entropy Alloy Discovery: Phase Prediction: Sima Alidokht1; Ehsan Gerashi1; Armin Hatefi1; 1Memorial University
High-entropy alloys (HEAs) have gained significant attention in materials science for their remarkable mechanical properties and extensive compositional versatility. Due to their high-dimensional chemical complexity, understanding their physical mechanisms and designing new HEAs is challenging. Predicting HEA phases can provide valuable insights, including mechanical properties anticipations. The conventional trial-and-error approach for discovering new HEAs is time-consuming and costly. To address the issue, we employ the power of machine learning methods to predict the phase of HEAs, reducing the effort required for HEA design. In this research, we propose various statistical and machine learning and artificial neural networks to model the HEAs phase responses, estimate the model parameters and explain the relationship between the HEAs phase features. Through extensive numerical experiments, we investigate the effects of design parameters in identifying various phases and evaluate the performance of the proposed models in estimating and predicting the HEA phases.
Cancelled
Wire Arc Additive Manufacturing of Fe-rich CrMnFeCoNi High Entropy Tribological Alloy: Ehsan Gerashi1; Andrej Klapatyuk2; Alexandr Gaivoronskii2; Anatoliy Zavdoveev2; Richard Chromik3; Xili Duan1; Sima Alidokht1; 1Memorial University of Newfoundland; 2Paton Electric Welding Institute of NAS of Ukraine; 3McGill University
High entropy alloys (HEAs) are alloys that contain five or more principal elements in approximately equal atomic percentages. These alloys, whether in the form of bulk materials or coatings, exhibit potential for harsh environment applications due to their exceptional combination of mechanical, thermal, and corrosion-resistance properties. This research aimed to develop Fe-rich CrMnFeCoNi HEA coatings using wire arc additive manufacturing (WAAM). Microstructural analysis, mechanical testing, and tribological evaluations were conducted to assess coating properties. The wear behavior of these coatings against a WC-Co countersphere was tested at room temperature. Various characterization techniques, including X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and Raman spectroscopy for phase analysis, scanning electron microscopy (SEM) for cross-section microscopy and phase compositions, were employed. SEM was used to reveal surface morphologies and cross-sectional analysis of the wear track. Friction and wear behavior of additively manufactured parts were discussed in relation to their mechanical properties and microstructure.
A Proposed Structure of the Rhombohedral μ Phase of FeNiMoW Using Atomistic Calculations: Sarah O'Brien1; Matthew Beck1; 1University of Kentucky
The multi-principal element alloy (MPEA) FeNiMoW contains three phases: FCC matrix (Fe40Ni40Mo16W4), BCC dendrites (Mo40W60), and rhombohedral μ phase (Fe13Ni8Mo13W5). FeNiMoW demonstrates adiabatic shear banding in a lamellar structure of FCC and μ phases. Previously Liu et al. highlighted the μ phase’s A7B6 crystal structure, e.g. Fe7Mo6. Experimental techniques like nanoindentation and XRD struggle to isolate the μ phase in the lamellar structure due to it being a few microns wide and shallow. Atomistic calculations, like DFT and DFPT, thus become extremely useful tools for characterizing the μ phase. Potential μ phase structures have been proposed, including: a solid solution, ordered unit cells derived from Fe7Mo6 to maintain symmetry, and two sublattices based on Fe7Mo6, with a Fe and Ni solid solution sublattice and Mo and W sublattice. Here, we present results supporting the interlocking sublattice structure being the most stable and probable structure over a range of temperatures.
Third Element Effect of FeCrAl in Aqueous Environments: Catherine Lynch1; 1University of Virginia
The third element effect refers to the component of a ternary alloy which forms an oxide of intermediate stability to the other two metals. This third element reduces the concentration of the oxide-forming component required for protective oxide film formation. This effect is studied in the FeCrAl system to observe the interrelationship between chromium and aluminum on film growth under low pH Na2SO4 corrosive environments. This work examines elemental interactions obscured in more complex multi-principal element alloys. While FeAl binaries form poorly protective oxides in aqueous environments, adding aluminum to FeCr alloys generates a protective chromia film below the standard chromium threshold. Linear sweep voltammetry of FeCrAl ternaries with 10at% Cr and variable Al concentrations indicates Al improves the passivation performance of low Cr FeCrAl alloys. Electrochemical impedance spectroscopy is used to explore the growth rate of these films and X-ray photoelectron spectroscopy is used to characterize the films’ composition and valence states, exploring the underlying mechanisms of this phenomenon.
Influence of Si on Latent Heat Release in Solidification and Microstructures of CrFeCoNi-Si Alloys: Jinno Maika1; Toru Maruyama1; 1Graduate of Kansai university
Some high-entropy alloys (HEAs) like CrMnFeCoNi alloy show excellent low-temperature toughness due to TWIP resulting from their low stacking fault energy (SFE). Alloying Si into this type of HEAs has been expected to improve the balance between strength and ductility because first-principles calculations have shown SFE of the HEAs alloyed with Si locally increases.The influence of Si content on the phase transformation process and temperature was investigated to obtain fundamental knowledge for the preparation and understanding of this alloy.CrFeCoNi alloys with Si content of 13-20at% were prepared by the casting process. Two latent heat releases were detected from the thermal analysis curve during cooling. One at the high temperature side was the melting point, which decreased with increasing Si content. The other the formation of the second phase. It was almost constant regardless of Si content, suggesting that the latent heat release was caused by an invariant reaction.
Mechanical and Tribological Properties of (CoCrFeNiMn)1-x-Tix high-Entropy Thin Film Synthesized by Magnetron Sputtering: Lin Wu1; Tongyue Liang1; Richard Chromik1; 1McGill University
Using Cantor alloy and Ti targets, (CoCrFeNiMn)1-x-Tix (x = 0, 4, 12, 24 in at. %) high-entropy thin films were deposited by pulsed direct current magnetron sputtering on silicon wafers. The effect of Ti content on microstructure, mechanical and tribological properties were studied. Within the variation of Ti content, all films showed a columnar structure, but with increasing Ti content there was a trend from FCC crystalline structure (0 at. % Ti) to nearly amorphous (24 at. % Ti). Using nanoindentation, film hardness (H) and reduced elastic modulus (Er) were measured. The highest H/Er and H3/Er2 values, potential indicators of wear resistance, were found with the minor addition of Ti. The tribological properties of the (CoCrFeNiMn)1-x-Tix films were evaluated by the micro-tribological test. The friction and wear behavior of the films were revealed, and the wear mechanism will be discussed.
Superconductivity in a New High-entropy Alloy Nb34Ti33Mo11Hf11V11: Bartosz Rusin1; Wojciech Nowak1; Michał Babij2; Rafał Idczak1; 1Institute of Experimental Physics, University of Wroclaw; 2Institute of Low Temepratures and Structural Research, Polish Academy of Sciences
High-entropy alloy (HEA) superconductors have attracted attention since the discovery of superconductivity in Ta34Nb33Hf8Zr14Ti11 in 2014 [1]. Superconducting HEA are the new category of disordered superconductors which exhibit great stability in high temperatures and robustness to high pressures and magnetic fields [2]. Their properties make them suitable for being used in extreme conditions, for example, as high field magnets. In this work, we present superconductive properties of a new HEA Nb34Ti33Mo11Hf11V11. High-entropy alloy was synthesized by arc melting. Physical properties of the system were characterized by means of X-ray powder diffraction, magnetization, electrical resistivity, and specific heat measurements. Experimental data revealed that Nb34Ti33Mo11Hf11V11 is a microscopically homogeneous mixture of the five constituent elements, crystalizes in body-centered cubic structure and exhibits type-II superconductivity at low temperatures. [1] P. Koželj et al., Phys. Rev. Lett. 113 (2014) 107001.[2] L. Sun, R. J. Cava, Phys. Rev. Mater. 3 (2019) 090301.
Radiation Damage Resistance Dependent on Compositional Complexity in Molybdenum-Based Alloys: Emily Hopkins1; Annie Barnett1; Khalid Hattar2; Mitra Taheri1; 1Johns Hopkins University; 2University of Tennessee - Knoxville
Body-centered cubic refractory high-entropy alloys (RHEAs) are proposed for the next generation of materials suitable for fusion reactor components due to their outstanding high-temperature strength, and radiation tolerant properties. This study investigates compositionally gradient Mo-based alloys and explores radiation resistance dependent on chemical complexity using transmission electron microscopy techniques. Structural observations collected via in situ transmission electron microscopy (TEM) and precession electron diffraction automated crystallographic orientation mapping (PED-ACOM) reveal indicators of increasing radiation tolerance in alloys with increased complexity under high temperature conditions. By providing fundamental analysis of the impact of additional components on damage resistance, we approach a mechanistic understanding of grain boundary and matrix effects on defect accommodation in RHEAs.
High Entropy Perovskite as Chromium Resistant Air Electrode for Intermediate-temperature Solid Oxide Electrolysis Cells: Awa Kalu1; Xingbo Liu1; Wenyuan Li1; 1West Virginia University
Our research focuses on improving the performance and chromium resistance of Lanthanum Nickelate (LNO) air electrode solid oxide cells (SOCs). We use simple perovskite and high entropy perovskite (HEP) as the surface coating of the LNO backbone. It has been shown that simple perovskite coatings boost the oxygen exchange capabilities of LNO. This improvement is attributed to the introduction of transition metal cations into the LNO structure, enhancing its performance and suggesting the potential for tailored performance enhancements. The real highlight lies in the outstanding performance of HEP coatings. LNO coated with LSPYB demonstrated exceptional performance under normal and aging conditions. LNO coated with LSPGB showed remarkable resistance to chromium exposure, displaying significantly better performance than the self-coated LNO in chromium-rich environments. The unique behavior of LNO+LSPGB suggests its ability to withstand and potentially excel in challenging conditions. Our findings emphasize the potential of high entropy perovskite to enhance LNO's catalytic properties, paving the way for the development of stronger materials for SOCs and other applications where superior performance and durability are essential.
Laser Shock Peening Surface Modification Effects on Microstructure and Oxidation Behavior of NbTiCoCrNi Refractory Complex Concentrated Alloys: Ugochukwu Ochieze1; Ravi Kumar1; Sravya Josyula1; Abdulquadri Oriola1; Matthew Steiner1; Eric Payton1; 1University of Cincinnati
Refractory complex concentrated alloys, considered for applications in extreme environments, are known for their susceptibility to oxygen absorption during use. Most research has predominantly concentrated on their solid solution behavior at high temperatures, largely disregarding their transition through lower temperature regimes as they progress towards higher service temperatures. Furthermore, such investigations have frequently utilized arcmelted buttons, which may not accurately represent components prepared for deployment in extreme environmental conditions. To address these limitations, this study examines the impact of laser shock peening as a surface treatment process on as-cast NbTiCoCrNi alloys. The microstructure, both pre- and post-surface treatment, is extensively characterized through analytical electron microscopy and X-ray diffraction. The findings of this research aim to assess the influence of microstructure modification and the introduction of high near-surface compressive residual stresses on the oxidation behavior. Particular attention is given to temperatures where the presence of multiple phases in equilibrium is expected.
Cancelled
Synthesis and Characterization of High-Cr and High-Co Duplex High Entropy Alloys in the CrCoNiAl System: Pedro Oliveira1; Gabriel Leal1; Francisco Coury1; 1Federal University of Sao Carlos
This study focused on duplex systems in High Entropy Alloys (HEAs), which are primarily composed of face-centered cubic (FCC) or body-centered (BCC) structures. However, limited information is available regarding HEAs containing both FCC and BCC phases. To address this gap, thermodynamic calculations were conducted to identify four non-equiatomic compositions in the CrCoNi and CrCoNiAl systems, enriched with high levels of Cr and Co, to form duplex structures (FCC/BCC). Incorporating aluminum Al expanded the duplex field by stabilizing the BCC phase, allowing for increased ductility by adding more cobalt to the alloys. The alloys underwent characterization in various conditions, including as cast, homogenized, cold rolled, and recrystallized states, using optical microscopy, X-ray diffraction (XRD), and Vickers micro hardness. The findings demonstrated that the alloys Co15Ni33.5Cr51.5, Co15Ni32Cr48Al5, and Co34Ni16Cr45Al5 exhibited a dual-phase structure. Conversely, the Co35Ni15.5Cr49 alloy did not possess a duplex structure, due to the narrow duplex field predicted by CALPHAD.