Article
Materials Science, Multidisciplinary
Yujie Chen, Dengke Chen, Xianghai An, Yin Zhang, Zhifeng Zhou, Song Lu, Paul Munroe, Sam Zhang, Xiaozhou Liao, Ting Zhu, Zonghan Xie
Summary: The emergence of multi-principal element alloys (MPEAs) brings great promise for high performance metallic materials. This study reports a new deformation mechanism of mechanically-induced dual phase transformations in the CrCoNi medium-entropy alloy, showing the potential for enhancing the mechanical properties of advanced alloys.
Article
Materials Science, Multidisciplinary
Huabing Li, Yu Han, Hao Feng, Gang Zhou, Zhouhua Jiang, Minghui Cai, Yizhuang Li, Mingxin Huang
Summary: This study demonstrates that nitrogen doping can suppress the formation of deformation twins in a CrMnFeCoNi high entropy alloy and significantly enhance its strength at 77 K without sacrificing much ductility. Microstructural characterization and first-principles calculations uncover the role of interstitial nitrogen atoms in achieving this excellent combination of strength and ductility. The addition of nitrogen increases the generalized stacking fault energy and reduces twinning, while the pinning of dislocations by nitrogen atoms effectively inhibits dislocation cross-slip and dynamic recovery, thereby promoting the accumulation of dislocations. The high dislocation density contributes to high strain hardening capacity and improved uniform elongation, compensating for the ductility loss caused by solid solution strengthening. The effect of nitrogen doping enriches the design concept of high- and medium-entropy alloys and provides an economical and effective strategy for developing ultra-high-performance alloys suitable for cryogenic applications.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Wujing Fu, Kefu Gan, Yongjiang Huang, Zhiliang Ning, Jianfei Sun, Fuyang Cao
Summary: The evolution of the deformation mechanism of CrMnFeCoNi high entropy alloy under cryogenic temperature was investigated through compressive experiments and transmission electron microscopy character-ization. It was found that the deformation mode of the alloy at 123 K can be divided into two stages, helping to understand the temperature dependent deformation mechanism of high entropy alloys.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Nanoscience & Nanotechnology
M. N. Hasan, J. Gu, S. Jiang, H. J. Wang, M. Cabral, S. Ni, X. H. An, M. Song, L. M. Shen, X. Z. Liao
Summary: The study investigates the effect of elemental segregation on local hardness and microstructural evolution induced by high strain-rate deformation in a CrMnFeCoNi high entropy alloy. Mn and Ni tend to segregate to interdendritic boundaries during solidification and this segregation is further intensified by dynamic deformation. The increase in local stacking fault energy in Mn and Ni enriched areas leads to a reduction in local hardness, altering the deformation mechanisms and hindering the propagation of adiabatic shear bands.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Caitao Fan, Luyao Li, Wenxin Wen, Hongzhen Li, Jianan Fu, Wenqing Ruan, Shuai Ren, Sajad Sohrabi, Zhenxuan Zhang, Xiong Liang, Jiang Ma
Summary: Due to their unique design concept, high-entropy alloys (HEAs) exhibit unusual properties and lead to an emerging new field. In this study, it is shown that a typical face-centered cubic crystalline phase CoCrFeNiMn HEA can be easily transformed into the amorphous phase through ultrasonic vibration treatment at a frequency of 20000 Hz. Nanoscale hierarchical features, including twins, stacking faults bands, hexagonal-close packed phase bands, and amorphous bands, can be clearly observed in samples treated with different ultrasonic vibration energies. The main mechanism of ultrasonic vibration-induced amorphization is the promotion of amorphous phase formation through grain refinement when the defect density at grain boundaries reaches a critical level. Furthermore, mechanical instability is easily induced by ultrasonic vibration at high strain rate to generate amorphous phase inside grains. As a result of ultrasonic vibration treatment, the HEA samples exhibit significant improvement in mechanical performance, mainly attributed to microstructure evolution, especially the generation of the amorphous phase, such as yielding strength and hardness. This rapid amorphization process not only provides a potential strengthening mechanism for HEAs but also offers a novel approach to investigate the crystal-amorphous transition problem.
MATERIALS & DESIGN
(2023)
Article
Metallurgy & Metallurgical Engineering
Tiezhuang Han, Jing Wang, Bo Li, Shuang Li, Kaisheng Ming, Fucheng Wang, Bin Miao, Shijian Zheng
Summary: The corrosion behavior of CrMnFeCoNi high entropy alloy after intermediate temperature fatigue test was investigated. Higher strain amplitude not only promoted precipitates generation but also spread the nucleation sites. The deterioration in corrosion resistance was attributed to the increase of precipitates, which destroyed the stability of the passive film.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Milan Heczko, Veronika Mazanova, Roman Groger, Tomas Zalezak, Mohammad S. Hooshmand, Easo P. George, Michael J. Mills, Antonin Dlouhy
Summary: The influence of small plastic pre-strains on the elevated-temperature stability and microstructure of the equiatomic CrMnFeCoNi FCC solid solution was investigated, with no enrichment of alloy elements near dislocation cores observed after pre-deformation and annealing. However, the formation of a Cr-rich tetragonal sigma phase and NiMn phase near grain boundaries was observed during prolonged annealing, indicating slow Cr diffusion towards grain boundaries and rapid diffusion along them to form precipitates.
Article
Engineering, Mechanical
Yu Qiao, Yan Chen, Fu-Hua Cao, Hai-Ying Wang, Lan-Hong Dai
Summary: This paper reveals the unusual simultaneous strength-plasticity enhancement and high strain rate embrittlement inhibition of CrMnFeCoNi HEA in impact tension through split Hopkinson tensile bar (SHTB) testing and high-speed photography. Microstructural analysis shows that the cooperation of twins and dislocations is the crucial mechanism for the synchronous enhancement of strength-plasticity in this alloy under impact tension. A thermo-viscoplastic constitutive model based on dislocations and twins evolution was developed to describe the dynamic mechanical behavior of HEAs at high strain rates.
INTERNATIONAL JOURNAL OF IMPACT ENGINEERING
(2021)
Article
Nanoscience & Nanotechnology
Chengbin Wei, Yiping Lu, Xinghao Du, Tingju Li, Tongmin Wang, Peter K. Liaw
Summary: The non-equiatomic Co29Cr29Fe29Ni12.5W0.5 high-entropy alloy exhibited exceptional strength-ductility synergy at cryogenic temperatures, with significant increase in yield strength and outstanding ductility. The microstructure transformed to a hexagonal-close packed phase at low temperatures, contributing to the high mechanical properties observed.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Multidisciplinary Sciences
Hao Wang, Dengke Chen, Xianghai An, Yin Zhang, Shijie Sun, Yanzhong Tian, Zhefeng Zhang, Anguo Wang, Jinqiao Liu, Min Song, Simon P. Ringer, Ting Zhu, Xiaozhou Liao
Summary: In situ straining transmission electron microscopy experiments on the Cantor high-entropy alloy (HEA) of CrMnFeCoNi demonstrate a crystalline-to-amorphous phase transformation in ultrafine-grained microstructures. The increase of crack-tip dislocation densities due to high lattice friction and grain boundary resistance triggers the transformation. The formation of amorphous nanobridges in the crack wake dissipates strain energies, providing effective toughening mechanisms for HEAs.
Article
Nanoscience & Nanotechnology
Wei Jiang, Xuzhou Gao, Yazhou Guo, Xiang Chen, Yonghao Zhao
Summary: In this study, the dynamic impact behavior and deformation mechanisms of a Cr26Mn20Fe20Co20Ni14 high-entropy alloy were systematically explored. The alloy exhibited uniform plastic deformation and a significant strain rate dependence in yield strength. Microstructural analyses revealed a transition in deformation mechanisms and interactions between different dislocations, stacking faults, and twins in strengthening the material. This work provides a comprehensive understanding of the high-entropy alloy's behavior and strengthening mechanisms.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Timothy A. Elmslie, Jacob Startt, Yang Yang, Sujeily Soto-Medina, Emma Zappala, Mark W. Meisel, Michele Manuel, Benjamin A. Frandsen, Remi Dingreville, James J. Hamlin
Summary: Magnetic properties of Cantor alloy samples with varying composition were investigated using magnetometry and muon spin relaxation. Two transitions were observed: a spin-glass-like transition between 55 K and 190 K depending on composition, and a ferrimagnetic transition at approximately 43 K in multiple samples. The magnetic signatures at 43 K were not affected by chemical composition. The effective magnetic moment decreased with increasing Cr or Mn concentrations and increased with decreasing Fe, Co, or Ni concentrations. The results provide insights into controllable tuning of the magnetic properties of Cantor alloy variants.
Article
Materials Science, Multidisciplinary
Kaisheng Ming, Bo Li, Lichen Bai, Ping Jiang, Xiaolei Wu, Shijian Zheng, Jian Wang
Summary: Under extremely low temperature, the CrMnFeCoNi high-entropy alloy exhibits dynamically reversible shear transformations, leading to the formation of dynamic nano-laminated dual-phase structures. These transformations enhance the strength, strain-hardening ability, and ductility of the alloy, providing a new approach to tackle the strength-ductility dilemma.
Article
Chemistry, Physical
Annica Wetzel, Marcus von der Au, Paul M. Dietrich, Joerg Radnik, Ozlem Ozcan, Julia Witt
Summary: This study investigated the corrosion characteristics of CrCoNi and CrMnFeCoNi alloys in different solutions, and found that CrCoNi exhibited better corrosion resistance.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Dae Cheol Yang, Yong Hee Jo, Yuji Ikeda, Fritz Koermann, Seok Su Sohn
Summary: Multi-principal element alloys show outstanding strength and toughness at cryogenic temperatures, attributed to the occurrence of deformation twins and a reduced stacking fault energy. The high-strength VCoNi alloy is expected to exhibit notable cryogenic properties. The effects of cryogenic temperature on tensile and impact properties are investigated, revealing temperature dependence of yield strength and deformation mechanism.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Materials Science, Ceramics
Hiroyuki Hayashi, Keita Kouzai, Yuta Morimitsu, Isao Tanaka
Summary: Despite extensive research, accurately predicting successful synthesis conditions for new pseudo-binary oxides remains a challenge. This study introduces a synthesis-condition recommender system to efficiently explore a wide chemistry space and successfully discovered two yet-to-be-found pseudo-binary oxides through systematic synthesis experiments.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Review
Chemistry, Physical
Ivan Novikov, Blazej Grabowski, Fritz Kormann, Alexander Shapeev
Summary: This paper presents a new class of machine-learning interatomic potentials called magnetic Moment Tensor Potentials (mMTPs). The mMTPs accurately reproduce both vibrational and magnetic degrees of freedom and utilize a two-step minimization scheme that coarse-grains the atomic and spin space. The performance of mMTPs is demonstrated through applications to a prototype magnetic system.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Christian Wagner, Alberto Ferrari, Jurgen Schreuer, Jean-Philippe Couzinie, Yuji Ikeda, Fritz Koermann, Gunther Eggeler, Easo P. George, Guillaume Laplanche
Summary: The physical properties of ten single-phase FCC CrxMn20Fe20Co20Ni40-x high-entropy alloys were investigated. The lattice parameters of the alloys were nearly independent of composition, while the solidus temperatures increased linearly with increasing Cr content. The alloys did not exhibit ferromagnetism in a certain temperature range, and the temperature dependencies of their coefficients of thermal expansion and elastic moduli were independent of composition. Ab initio simulations qualitatively reproduced the magnetic transitions and magnetostriction observed in the alloys. The plastic deformation of the alloys was found to occur initially by the glide of perfect dislocations on {111} planes. The stacking fault energy (SFE) was determined and found to decrease with increasing Cr content. However, the calculated intrinsic SFEs were lower than the experimental values. The ab initio simulations showed that atomic relaxations, finite temperatures, and magnetism strongly influenced the intrinsic SFE.
Article
Materials Science, Multidisciplinary
Hyun Chung, Dae Woong Kim, Woo Jin Cho, Heung Nam Han, Yuji Ikeda, Shoji Ishibashi, Fritz Kormann, Seok Su Sohn
Summary: High- and medium-entropy alloys with high solid-solution strength have significant effects on strain-hardening rate. In this study, the role of solid-solution strengthening on strain-hardening rate was revealed by controlling the Cr/V ratio in V1-xCrxCoNi alloys and investigating the evolution of deformation structures. The results showed that under the activated huge solid-solution strengthening effect, dislocation-mediated plasticity can be predominant over twinning, leading to an overall higher strain-hardening rate in the V-rich alloys.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Yuji Ikeda, Deven P. Estes, Blazej Grabowski
Summary: This study provides a comprehensive understanding of H adsorption on MoO3 in the bulk and on the surface, resolving discrepancies from previous ab initio studies. The energetically favorable position for H adsorption is found to be the asymmetric oxygen site. The results have important implications for the understanding of MoO3 as a hydrogen storage material.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Materials Science, Ceramics
Hiroyuki Hayashi, Yuta Morimitsu, Ikko Tatsumi, Isao Tanaka
Summary: This study demonstrates the use of coordination polymers (CPs) as precursors for simple and complex oxide synthesis. By investigating the conditions for different metal ion solutions, CPs were obtained as precursors for simple oxides. Experiments were then conducted to successfully prepare precursors for 10 complex oxides, including three that could not be synthesized using traditional methods.
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Abbas Mohammadi, Yuji Ikeda, Parisa Edalati, Masaki Mito, Blazej Grabowski, Hai-Wen Li, Kaveh Edalati
Summary: This study develops high-entropy alloys (HEAs) for room-temperature hydrogen storage through a combination of first-principles calculations and experiments. The HEAs can reversibly store hydrogen in the form of Laves phase hydrides at room temperature with fast hydrogenation kinetics and stable storage performance.
Article
Multidisciplinary Sciences
Ziyuan Rao, Po-Yen Tung, Ruiwen Xie, Ye Wei, Hongbin Zhang, Alberto Ferrari, T. P. C. Klaver, Fritz Koermann, Prithiv Thoudden Sukumar, Alisson Kwiatkowski da Silva, Yao Chen, Zhiming Li, Dirk Ponge, Joerg Neugebauer, Oliver Gutfleisch, Stefan Bauer, Dierk Raabe
Summary: This study proposes an active learning strategy to accelerate the design of high-entropy Invar alloys. By integrating machine learning with density-functional theory, thermodynamic calculations, and experiments, the researchers successfully identified high-entropy Invar alloys with extremely low thermal expansion coefficients. This approach shows promise for the fast and automated discovery of high-entropy alloys with optimal thermal, magnetic, and electrical properties.
Review
Chemistry, Physical
Hiroyuki Hayashi, Atsuto Seko, Isao Tanaka
Summary: A recommender system based on experimental databases is crucial for the discovery of inorganic compounds. This review examines different methods used in the discovery of unknown compounds and demonstrates their effectiveness. By using compositional descriptors or tensor decomposition techniques, predictive performance can be improved, leading to successful synthesis of previously unknown compounds.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sheuly Ghosh, Vadim Sotskov, Alexander Shapeev, Joerg Neugebauer, Fritz Koermann
Summary: In this study, we analyze the temperature-dependent atomic short-range ordering and phase stability of the face-centered cubic CrCoNi medium-entropy alloy. We employ a combination of ab initio calculations and on-lattice machine learning interatomic potentials. The temperature-dependent properties are studied using canonical Monte Carlo simulations. A phase transition into an ordered Cr(Ni, Co)(2) phase (MoPt2-type) is observed at around 975 K. We demonstrate that magnetism is not responsible for the observed chemical ordering.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Kohei Shinohara, Atsushi Togo, Isao Tanaka
Summary: This paper presents an algorithm for computational crystallography of magnetic materials. It includes the determination of magnetic symmetry operations, identification of magnetic space-group types, transformation to specific settings, and symmetrization of magnetic crystal structures using projection operators.
ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES
(2023)
Article
Materials Science, Multidisciplinary
Prashanth Srinivasan, Alexander Shapeev, Joerg Neugebauer, Fritz Koermann, Blazej Grabowski
Summary: The anharmonic behavior of group V and group VI bcc refractory elements show qualitative differences. Group V elements have small and mostly negative anharmonic entropy, while group VI elements have large positive anharmonic entropy that increases with temperature. This difference is explained through accurate calculations and comparisons with experimental data.
Article
Materials Science, Multidisciplinary
Yongliang Ou, Yuji Ikeda, Oliver Clemens, Blazej Grabowski
Summary: The impact of ordered vacancies on the dynamic stability of perovskites was investigated. The study found that ordered vacancies do not significantly affect the critical temperature of perovskites, but the vacancy-ordered structure exhibits strong anharmonicity above its critical temperature.
Article
Materials Science, Multidisciplinary
Ying Zhou, Prashanth Srinivasan, Fritz Kormann, Blazej Grabowski, Roger Smith, Pooja Goddard, Andrew Ian Duff
Summary: Multi-principal-component alloys, such as high entropy alloys (HEAs), have unique properties and a vast compositional space, making them attractive for alloy design. This study focuses on using computational materials design to investigate the high-temperature properties of HEAs, specifically the full free energy surface and thermodynamic properties. The developed approach, based on density-functional theory and machine learning, shows a significant speed-up and accurate predictions of high-temperature free energy. The study is performed on an equiatomic HEA composition, which may have potential applications in next generation fission and fusion reactors.
