Article
Materials Science, Multidisciplinary
Ameey Anupam, Andrew S. M. Ang, K. Guruvidyathri, Musharaf Abbas, D. Sivaprahasam, Paul Munroe, C. C. Berndt, B. S. Murty, Ravi Sankar Kottada
Summary: The oxidation behavior of five high entropy alloys (HEAs) at 1100°C has been studied, with Al2CoCrFeNi and AlCoCr0.5Ni HEAs showing the lowest oxidation rates. The presence of Al-rich nanoscale precipitates aids in protective oxide growth, while the Al-lean phase fraction and its Al content have a significant impact on the alloy's oxidation behavior. A parameter "X" has been introduced to potentially shortlist HEAs for oxidation resistance applications, based on the ratio of these two factors and CALPHAD predictions.
Article
Nanoscience & Nanotechnology
Hailong Huang, Yan Sun, Peipei Cao, Yuan Wu, Xiongjun Liu, Suihe Jiang, Hui Wang, Zhaoping Lu
Summary: This study extensively investigated the phase stability of high entropy alloys (HEAs) at intermediate temperatures and found that the effect of cooling rates on refractory HEAs depends on the alloy composition and material properties. This provides a new approach for optimizing the properties of HEAs.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
E. Panina, N. Yurchenko, G. Salishchev, S. Zherebtsov, N. Stepanov
Summary: The effect of long-term annealing on the structure and mechanical properties of refractory high entropy alloys was investigated. Annealing did not result in the formation of additional phases, but led to the formation of nanoprecipitates and separate phases inside the initial phases. The alloys were significantly strengthened and showed potential for the development of high entropy alloys with a stable structure.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
K. Srimark, S. Dasari, A. Sharma, P. Wangyao, B. Gwalani, T. Rojhirunsakool, S. Gorsse, R. Banerjee
Summary: This study reveals that the alternating FCC and BCC lamellar microstructure in the Al0.7CoCrFeNi high entropy alloy is a result of non-equilibrium partitionless solidification followed by solid-state decomposition. Isothermal annealing further drives these individual sub-systems towards equilibrium via precipitation of ordered intermetallic phases. The transformation in FCC lamellae initiates by the formation of metastable L1(2) precipitates at shorter annealing times, which are eventually replaced by the equilibrium BCC and B2 phases.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Multidisciplinary
Taiwen Huang, Jiachen Zhang, Jun Zhang, Lin Liu
Summary: Alloy design of Cr-Co-Ni-Ta eutectic medium entropy alloys was conducted using a CALPHAD method coupled with experimental study, revealing changes in microstructure and mechanical properties with increasing Ta content. CrCoNiTa0.4 EMEA alloy exhibited the highest hardness and compression strength, making it one of the most promising alloys in the study.
APPLIED SCIENCES-BASEL
(2021)
Article
Nanoscience & Nanotechnology
Jiyeon Kang, Nokeun Park, Jin-Kyung Kim, Joo Hyun Park
Summary: The study focuses on microstructures and mechanical properties of high entropy alloy (CoCrFeMnNi)95.2Al3.2Ti1.6 after homogenization and cold-rolling, followed by annealing at various temperatures. The annealing process revealed the presence of different phases based on temperature, leading to changes in grain size, strength, and ductility. Fully recrystallized materials at 900°C exhibited lower grain size but higher ductility due to second phase particles, impacting the yield strength significantly.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Xu Cao, Changjun Wu, Ya Liu, Haoping Peng, Xuping Su
Summary: This study experimentally and thermodynamically investigates seven arc-melted and annealed CoCrFeNiNbx (x = 0.3-0.6) alloys. The microstructure of the alloys is found to be significantly affected by cooling rate and annealing treatment. A method of strengthening the alloy by precipitating a T phase is proposed.
Article
Chemistry, Physical
Zihui Dong, Dmitry Sergeev, Michael F. Dodge, Francesco Fanicchia, Michael Mueller, Shiladitya Paul, Hongbiao Dong
Summary: The study on CoCrFeMoNi high entropy alloys reveals their potential for high temperature coating applications, with phase transitions and structural characteristics providing key information for the development of similar thermal spray HEA coatings.
Article
Chemistry, Physical
Jiaojiao Yi, Lin Yang, Mingqin Xu, Lu Wang, Lisha Liu, Long Zeng
Summary: In this study, the phase components, microstructures, and compressive properties of a novel 3D transition metal high entropy alloy CuFeNiTiV in the as-cast condition were investigated. The thermodynamic simulations revealed the order of phase separation during solidification, which was confirmed by XRD analysis of the alloy's phase components. The outstanding fracture strength of 2086 MPa in the as-cast alloy was attributed to the deformation resistance of both the major BCC phase and laves phase.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Lu Wang, Jiarui Wang, Hongwei Niu, Gongji Yang, Lin Yang, Mingqin Xu, Jiaojiao Yi
Summary: A near-eutectic high-entropy alloy with a soft-hard dual-phase structure was developed by adjusting the composition ratio and annealing process. The alloy exhibited high yield strength and moderate plasticity, but the homogenization process resulted in the formation of micro-pores, leading to a decrease in mechanical properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Norhuda Hidayah Nordin, Leong Zhaoyuan, Russell Goodall, Iain Todd
Summary: Control over a lamellar-like-structured high entropy alloy system can be achieved by replacing aluminum with boron. The addition of boron influences the microstructure and phase formation, and the presence of Fe2B phase correlates with interfacial energy.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Materials Science, Multidisciplinary
K. X. Yin, G. Y. Dong, G. J. Zhang, Q. W. Tian, Y. N. Wang, J. C. Huang
Summary: In this paper, new parameters are developed to assess phase constitutions of solid solutions in 124 HEA systems. A thermodynamic parameter DGF_B is presented to estimate the propensity for a material system to form BCC or FCC solid solutions based on the comparison of their Gibbs free energies. The presence of B2 and L12 ordered phases is found to affect the prediction accuracy, so a new ratio parameter is introduced to predict the structures of solid solution phases.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
X. J. Gao, L. Wang, N. N. Guo, L. S. Luo, G. M. Zhu, C. C. Shi, Y. Q. Su, J. J. Guo
Summary: This paper investigates the effects of Cr addition on the microstructure, phase constitutes, and mechanical properties of the Hf0.5Mo0.5NbTiZr refractory high-entropy alloy. The addition of Cr refines the dendritic structure, increases the strength, and influences the plasticity of the alloy. Homogenization treatment promotes the formation of Laves phase and significantly enhances the strength of the alloy.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Mingze Wang, Zhiqin Wen, Junxiao Liu, Jingyang Wang, Zhenyu Wu, Jiedong Qin, Yuhong Zhao
Summary: In this study, CoCrFeNi-M0.4 (M = Zr, Hf, 50 %Zr + 50 %Hf) EHEAs were fabricated using a selective vacuum arc furnace to control the content of Zr and Hf element and achieve a balance between strength and plasticity in HEAs. Alloying with Zr or Hf resulted in a cross fluvial eutectic structure consisting of FCC-CoCrFeNi matrix phase and intermetallic in CoCrFeNiZr0.4 and CoCrFeNiHf0.4. CoCrFeNiZr0.2Hf0.2, which is synergistic alloying with Zr and Hf, exhibited a brawny river eutectic structure of both soft FCC and hard Ni7Hf2 intermetallic. The synergistic precipitation strengthening and solid solution strengthening led to a fracture strength of 3475.7 MPa and a ductility of 14.1% in CoCrFeNiZr0.2Hf0.2. Furthermore, CoCrFeNiZr0.2Hf0.2 showed a good combination of strength and plasticity through the synergistic alloying effect compared with other CoCrFeNi HEAs.
Article
Chemistry, Physical
Huinan Chang, Yiwen Tao, Peter K. Liaw, Jingli Ren
Summary: In this study, the formation and stability of solid-solution phases in high-entropy alloys were predicted using machine learning. The root mean square residual strain was identified as the most critical parameter, and its effectiveness in quantitatively predicting the stability of solid-solution phases was confirmed. Different algorithms were compared, and the support vector machine was found to be the best algorithm for predicting the phase formation of high-entropy alloys.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Sergey Mironov, Maxim Ozerov, Alexander Kalinenko, Nikita Stepanov, Oleg Plekhov, Ruslan Sikhamov, Volker Ventzke, Nikolai Kashaev, Gennady Salishchev, Lee Semiatin, Sergey Zherebtsov
Summary: The relationship between residual stress and microstructure evolution during laser shock peening of Ti-6Al-4V was investigated. It was found that the unique residual stress state generated during this process is attributed to the very high imposed energy and the extremely short time scale, which inhibits dislocation cross-slip and climb, thus affecting deformation and microstructure evolution.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
N. Yurchenko, E. Panina, A. Belyakov, G. Salishchev, S. Zherebtsov, N. Stepanov
Summary: High-entropy intermetallics show great potential for high-temperature applications, but there is limited information on their plastic flow behavior and deformation mechanisms. A yield strength anomaly was observed in a refractory AlNbTiVZr0.25 high-entropy alloy during compression tests, possibly connected to the glide of dissociated a (111) superdislocations.
Article
Nanoscience & Nanotechnology
E. Povolyaeva, S. Mironov, D. Shaysultanov, N. Stepanov, S. Zherebtsov
Summary: A new medium-entropy Fe-65(CoNi)(25)Cr9.5C0.5 alloy was investigated for its properties at room and liquid nitrogen temperatures. The alloy exhibited high strength, good ductility, and excellent fracture toughness at cryogenic temperatures. The microstructure analysis suggested a phase transition induced by deformation, and the cold-rolled alloy showed improved mechanical properties compared to the as-cast alloy. Substructure strengthening, interphase strengthening, and solid solution strengthening were identified as contributing factors to the alloy's enhanced performance.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Chemistry, Physical
E. Panina, N. Yurchenko, A. Tojibaev, M. Mishunin, S. Zherebtsov, N. Stepanov
Summary: This study investigates the structure and mechanical properties of refractory high-entropy alloys, showing that a dual-phase structure can enhance both strength and ductility while exhibiting a yield stress anomaly under certain conditions.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
N. Yurchenko, E. Panina, A. Tojibaev, V. Novikov, G. Salishchev, S. Zherebtsov, N. Stepanov
Summary: This study demonstrated the diverse effects of B2 ordering on the tensile mechanical properties of new refractory medium-entropy alloys, AlxNb40Ti40V20-x (x = 0; 15; 20 at%). The impact of the ordering depended on the chemical composition. Al15Nb40Ti40V5 alloy, with weak B2 ordering, exhibited large uniform room-temperature elongation and moderate high-temperature strength. On the other hand, Al20Nb40Ti40 alloy, with high B2 ordering, was brittle at room temperature and sensitive to the testing environment at elevated temperatures. Meanwhile, it showed slower softening up to 0.4 Tm but lost strength faster above 0.4 Tm compared to the bcc Nb40Ti40V20 or weakly B2-ordered Al15Nb40Ti40V5 alloys. The factors responsible for these mechanical properties were thoroughly discussed.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
A. Semenyuk, S. Zherebtsov, N. Stepanov
Summary: The effect of adding different amounts of V and N on the properties of as-cast Fe40Mn40Co10Cr10-based high-entropy alloys was studied. It was found that a certain percentage of V and N significantly strengthen the alloy by precipitation of V2N-type nitrides. The precipitation-strengthened alloy with 2 at.% V and 1 at.% N had a yield strength of 440/940 MPa and uniform elongation of 36/18% at 293/77 K. The experimental data on the phase composition of the alloys agree reasonably well with the CALPHAD predictions.
Article
Nanoscience & Nanotechnology
N. Yurchenko, E. Panina, A. Tojibaev, V. Novikov, G. Salishchev, S. Zherebtsov, N. Stepanov
Summary: Here, it is demonstrated that the grain size, rather than the domain size, plays a crucial role in determining the room-temperature properties of a B2-ordered refractory Al15Nb40Ti40V5 medium-entropy alloy. Refining the grain size to 20 μm, regardless of the domain size, resulted in an elongation of approximately 50%, surpassing all previously reported refractory high/medium-entropy alloys.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Chemistry, Physical
Kirill Vasilevich Kuskov, Andrey A. A. Nepapushev, Sofiya Aydinyan, Dmitry G. G. Shaysultanov, Nikita D. D. Stepanov, Khachik Nazaretyan, Suren Kharatyan, Elena V. V. Zakharova, Dmitry S. S. Belov, Dmitry O. O. Moskovskikh
Summary: This research reports the direct production of a high-entropy intermetallic CoNi0.3Fe0.3Cr0.15Al material with a B2 structure from mechanically activated elemental powder mixtures. Various synthesis methods were used to obtain the desired powders and bulks. The formation of the main B2 phase and other secondary phases were observed, and the interaction between the components during heating was studied. The alloy synthesized by the reactive SPS method showed enhanced mechanical properties at elevated temperatures.
Article
Chemistry, Physical
Dmitrii Panov, Egor Kudryavtsev, Stanislav Naumov, Denis Klimenko, Ruslan Chernichenko, Vladimir Mirontsov, Nikita Stepanov, Sergey Zherebtsov, Gennady Salishchev, Alexey Pertcev
Summary: The study investigates the changes in microstructure and texture gradient of a 321-type metastable austenitic stainless steel during cold rotary swaging. Through cold rotary swaging with a 90% reduction at ambient temperature, significant gradients are observed in the volume fraction of alpha'-martensite, axial texture of austenite and alpha'-martensite, and non-uniform microhardness distribution along the rod diameter after an 80-90% reduction. Finite element analysis reveals moderate tensile stresses at the center and high compressive stresses at the edge, along with a temperature gradient due to water cooling and heating during the process. The paper discusses strain-induced martensitic transformation, microstructure and texture evolution, and non-uniform hardening during cold rotary swaging.
Article
Materials Science, Multidisciplinary
Maxim Ozerov, Nikita Yurchenko, Vitaly Sokolovsky, Elena Nozdracheva, Evgeniya Panina, Sergey Nadezhdin, Nikita Stepanov, Sergey Zherebtsov
Summary: Ti(50-x)Zr38NbxTa8Sn4 high-entropy alloys with x = 0, 10, and 20 at.% were produced. The Ti30Nb20 and Ti40Nb10 alloys showed untypical mechanical behavior with a short strain-hardening stage followed by a gradual decrease in flow stress after reaching the yield point. The Ti30Nb20 and Ti40Nb10 alloys have properties that make them highly attractive for biomedical application.
Article
Materials Science, Multidisciplinary
N. Yurchenko, E. Panina, A. Tojibaev, R. Eleti, D. Volosevich, O. Klimova-Korsmik, G. Salishchev, S. Zherebtsov, N. Stepanov
Summary: In this study, the influence of non-refractory elements on the mechanical behavior and microstructure of refractory high/medium alloys (RH/MEAs) was investigated. It was found that the addition of Al, a non-refractory element, can enhance both room-temperature tensile strength and ductility of the alloys by forming ordered nanodomains that change the dislocation glide character. These ordered nanodomains confine the dislocation motion and intensify the Portevin-Le Chatelier effect at certain temperatures, resulting in improved mechanical performance of the alloys.
Article
Chemistry, Physical
E. Povolyaeva, D. Shaysultanov, I. Astakhov, M. Klimova, S. Zherebtsov, N. Stepanov
Summary: This study investigated two medium-entropy alloys, Fe60 and Fe65, which underwent cold rolling and subsequent annealing. Fe60 alloy had a fcc structure, while Fe65 alloy contained a significant amount of bcc martensite. Fe65 alloy exhibited a stronger TRIP effect, leading to a more comprehensive combination of properties. Quantitative analysis of the structure-properties relationships revealed similarities and differences between the two alloys' behavior.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Sergey Mironov, Maxim Ozerov, Alexander Kalinenko, Ivan Zuiko, Nikita Stepanov, Oleg Plekhov, Gennady Salishchev, Lee Semiatin, Sergey Zherebtsov
Summary: Laser shock peening (LSP) is an innovative technique used to enhance fatigue strength in structural materials by generating significant residual stress. This study aimed to evaluate the plastic strain induced during LSP and improve the understanding of the process. Electron backscatter diffraction (EBSD) and nano-hardness measurements were conducted on laser-shock-peened Ti-6Al-4V alloy to examine the microstructural response. Minor changes were observed in the shape of α grains/particles and hardness, indicating a small plastic strain. This unexpected result was attributed to a relatively high rate of strain hardening in Ti-6Al-4V during LSP.
Article
Materials Science, Multidisciplinary
Maxim Ozerov, Nikita Stepanov, Vitaly Sokolovsky, Ilya Astakhov, Margarita Klimova, Alexander Galtsev, Lujun Huang, Sergey Zherebtsov
Summary: A metal-matrix composite with TiB reinforcing fibers was produced using vacuum arc melting, resulting in a 40% increase in strength compared to the unreinforced alloy. The composite exhibited a yield strength of 1100 MPa and a ductility of 10% in compression at room temperature. At elevated temperatures, the composite maintained a yield strength 1.5-2 times greater than the unreinforced alloy. The interphase boundary between TiB particles and the matrix was defect-free. Processing maps were analyzed for both the composite and the unreinforced alloy.
