High Entropy Alloys Research Papers (original) (raw)

2025, Metals

This paper introduces a novel functionally graded metallic syntactic foam. The investigated foams are manufactured while using infiltration casting where molten A356 aluminum flows into the interstitial voids of packed expanded perlite (EP) particle beds. The partial pre-compaction of particle beds enables the creation of distinct and reproducible density gradients within the syntactic foam. In this study, the samples are produced using four gradually increasing compaction forces and are compared to non-compacted samples. X-ray imaging is used to detect the resulting spatial variation of foam density. In addition, quasi-static compression tests are performed to determine the mechanical foam properties. The results suggest that particle pre-compaction is an efficient tool for tailoring the density and mechanical properties of these novel functionally graded materials.

2025, Materials

Zinc alloy (ZA27) syntactic foams (SF) were manufactured using expanded perlite (EP) particles and counter-gravity infiltration casting. Due to a variation of the metallic matrix content, the density of the produced foam samples varied from 1.78 to 2.03 g·cm−3. As-cast and solution heat-treated samples were tested to investigate the compressive properties of the ZA27 syntactic foam. To this end, quasi-static compression tests were conducted. In addition, microstructural analysis of the as-cast and heat-treated syntactic foams was carried out using scanning electron microscopy. The results indicate that the heat treatment alters the microstructure of the ZA27 alloy matrix from a multiphase dendrite to a spheroidized microstructure with improved ductility. Moreover, the heat treatment considerably enhances the energy absorption and plateau stress ( σ pl ) of the syntactic foam. Optical analysis of the syntactic foams under compression shows that the dominant deformation mechanism of t...

2025, Composites Part B: Engineering

This paper investigates the effect of temperature on the microstructure, failure mechanism and compressive mechanical properties of newly developed ZA27 syntactic foams. Two different types of filler particles are considered, i.e. expanded perlite (P) and expanded glass (G). Metallic syntactic foam (MSF) has been produced via a counter-gravity infiltration process of packed particle beds, followed by controlled thermal exposure. Quasi-static compressive tests were carried out on cylindrical samples at five different in-situ testing temperatures between 25 °C and 350 °C. At all considered temperatures, P-MSF exhibits superior mechanical properties compared to G-MSF. The mechanical properties of both foam types decrease significantly with increasing testing temperature. For comparison, solid ZA27 samples were compressed at the same testing temperatures. Due to microstructural changes, a significant strength degradation of solid ZA27 was observed starting at 100 °C. Comparison of results indicates that the temperature-dependent mechanical properties of P-MSF and G-MSF are strongly controlled by the matrix material. However, the addition of particles decreased the relative reduction of plateau stress and volumetric energy absorption of ZA27 MSF at elevated temperatures.

2025, Materials

In this research work, the effect of lateral loading (LL) on the crushing performance of empty tubes (ETs) and ex situ aluminum foam-filled tubes (FFTs) was investigated at 300 • C. The cylindrical thin-walled steel tube was filled with the closed-cell aluminum alloy foam that compressed under quasi-static loading conditions. During the compression test, the main mechanical properties of the ETs improved due to the interaction effect between the cellular structure of the foam and the inner wall of the empty tube. In addition, the initial propagated cracks on the steel tubes reduced considerably as a result of such interaction. Furthermore, the obtained results of the LL loading were compared with the axial loading (AL) results for both ETs and FFTs at the same temperature. The findings indicated that the application of loading on the lateral surface of the composite causes the lower mechanical properties of both ETs and FFTs in comparison with the axial loading conditions.

2025, Composite Structures

This study focuses on the effect of temperature on the mechanical behavior of closed cell aluminum-alloy foam filled tubes (FFTs) under quasi-static compressive loads. The results of the compressive testing indicated that at each tested temperature the closed-cell aluminum foam improves the mechanical properties of the empty steel tubes. This behavior is related to the interaction effect between the aluminum foam as filler material and the empty tubes. Also, it was observed that the deformation mechanism of FFTs at all tested temperatures is axisymmetric concertina mode with formation of two folds. Due to the softening phenomenon of the steel tube matrix with increasing of temperature the distribution and size of propagated micro-cracks on both loading surfaces and peripheral folds decreased significantly from the order of millimeters up to micrometers. Finally, it was observed that the increasing of the working temperature reduces the ability FFTs to absorb energy during compression test.

2025, International Journal of Electrochemical Science

During initial days of α-SABLIN (LAO , s) commercial plant operation, general corrosion was observed in the downstream separation columns. This was due to traces of catalyst not being completely neutralized thus forming acidic medium (mainly hydrochloric), resulting in the corrosion of the columns. In this respect the high temperature corrosion behavior of three important steel materials, namely carbon steel (CSA516) and ferritic (SS410) and austenitic (SS304L) stainless steels was studied by mass loss method at the process conditions and environment of the α-SABLIN (LAO , s) commercial plant. Measurements were conducted at 270 o C and 29 bar as a function of immersion time (up to 30 days). Such measurements are complemented with X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscopy (SEM). The obtained findings revealed that the three tested steel samples corrode in the environment of the α -SABLIN (LAO , s) commercial plant. The corrosion rate varies depending on the steel chemical composition, with SS304L being the most corrosion-resistant among the tested samples.

2025, Materials Science and Engineering: A

Mechanically alloyed amorphous Al 86 Ni 8 Y 6 powders were consolidated by spark plasma sintering (SPS) and the effect of varying sintering pressure (100-400 MPa) on phase transformation and resulting mechanical property was studied. Fully amorphous Al 86 Ni 8 Y 6 powder obtained via mechanical alloying exhibited good thermal stability with a wide glass transition range of 45 °C. Higher sintering pressure (400 MPa) during SPS resulted in (i) better densification (98%) with improved inter-particle bonding and moreover, (ii) retention of higher volume fraction ( $ 92 vol%) of amorphous phase with lower amount of intermetallic nano-precipitates, indicating improvement in thermal stability of the amorphous phase. Vickers microhardness test showed improvement in hardness with increasing sintering pressure attributed to a larger fraction of the retained amorphous phase and better inter-particle bonding. Nanoindentation test exhibited similar trends in hardness and elastic modulus with wide variation in hardness and elastic modulus values attributed to the distribution of comparatively soft nanocrystalline Al and very hard intermetallic precipitates in the amorphous matrix.

2025, Nature Communications

2025, Journal of Applied Physics

The formation of octonary DyErGdHoLuScTbY and senary DyGdHoLaTbY and ErGdHoLaTbY high-entropy alloys (HEAs) with the hexagonal close-packed (HCP) structure was reported in this study. Experiments using scanning electron microscopy and x-ray diffraction confirmed the single HCP solid solution in the as-cast state for these three HEAs if the presence of minor rare-earth oxides due to contamination from processing is ignored. The measured compressive yield stress values for these HEAs at room temperature are 245, 205, and 360 MPa for the ErGdHoLaTbY, DyGdHoLaTbY, and DyErGdHoLuScTbY HEAs, respectively. The corresponding solid solution strengthening contributions for these HEAs were estimated using a simple elastic model, and the resulting contributions were 28 MPa, 27 MPa, and 42 MPa for the three aforementioned HEAs.

2025, Materials Science and Engineering A-structural Materials Properties Microstructure and Processing

This study reports the design and development of ductile and strong refractory single-phase high-entropy alloys (HEAs) for high temperature applications, based on NbTaV with addition of Ti and W. Assisted by CALPHAD modeling, a single body-centered cubic solid solution phase was experimentally confirmed in the as-cast ingots using X-ray diffraction and scanning electron microscopy. The observed elementalsegregation in each alloy qualitatively agreeswith CALPHAD prediction.The Vickersmicrohardnesses(and yielding strengths) of the alloys are about 3 (and 3.5-4.4) times that those estimated from the rule ofmixture. WhileNbTaTiVWshows an impressive yielding strength of1,420MPa with fracture strain of 20%, NbTaTiV exhibits exceptional compressive ductility at room temperature.

2025

This paper presents ongoing research at NETL aimed at gaining fundamental understanding of high-entropy alloys (HEAs) formation and their properties, and developing highperformance HEAs for high-temperature fossil energy applications. First-principles density functional theory (DFT), Monte Carlo simulation, and molecular dynamics simulation are carried out to predict enthalpy of formation, the entropy sources (i.e., configurational entropy, vibrational entropy, and electronic entropy), and elastic properties of model single-phase HEAs with the face-centered cubic, body-centered cubic and hexagonal closed-packed structures. Classical elastic theory, which considers the interactions between dislocations and elastic fields of solutes, has also been used to predict solid solution strengthening. Large-size (~7.5 kg) HEAs ingots are produced using vacuum induction melting and electroslag remelting methods, followed by homogenization treatment resulting in greater than 99% homogeneity. Subsequent thermomechanical processing produces fully-wrought face-centered cubic microstructures. The tensile behavior for these alloys have been determined as a function of temperature, and based on these results screening creep tests have been performed at selected temperatures and stresses.

2025, Nature Communications

Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further improves the accuracy of the thermodynamic database of the discovered alloy system. This study shows that integrating high-throughput screening, multiscale modeling, and experimental validation proves to be efficient and useful in accelerating the discovery of advanced precipitation-strengthened structural materials tuned by the high-entropy alloy concept.

2025, JOM

This report presents a design methodology for refractory high-entropy alloys with a body-centered cubic (bcc) structure using select empirical parameters (i.e., enthalpy of mixing, atomic size difference, X-parameter, and electronegativity difference) and CALPHAD approach. Sixteen alloys in equimolar compositions ranging from quinary to ennead systems were designed with experimental verification studies performed on two alloys using x-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. Two bcc phases were identified in the as-cast HfMoNbTaTiVZr, whereas multiple phases formed in the as-cast HfMoNbTaTiVWZr. Observed elemental segregation in the alloys qualitatively agrees with CALPHAD prediction. Comparisons of the thermodynamic mixing properties for liquid and bcc phases using the Miedema model and CALPHAD are presented. This study demonstrates that CALPHAD is more effective in predicting HEA formation than empirical parameters, and new single bcc HEAs are suggested: HfMoNbTiZr, HfMoTaTiZr, NbTaTiVZr, HfMoNbTaTiZr, HfMoTaTiVZr, and MoNbTaTiVZr.

2025, Journal of Materials Engineering and Performance

The potential of high-entropy alloys (HEAs) to meet or exceed austenitic stainless steel performance with the additional benefit of improved hot corrosion/oxidation resistance makes FCC HEAs attractive for use in energy applications. While shorter-term creep tests have been reported in the literature on HEAs, not all methodologies utilize repeatable techniques. This manuscript reports on over 23,500 accumulated hours of tensile creep testing with adherence to ASTM standards on a melt-solidified ingot of CoCrFeNiMn HEA converted to wrought plate using conventional thermo-mechanical processing techniques. The typical standard creep analyses are reported, i.e., Larson-Miller parameter, Monkman-Grant relationship, activation energy for creep, and creep stress exponents were calculated and compared to previously reported short-term creep tests. Additionally, characteristics of creep fracture and microstructural evolution are reported with cursory dislocation mechanisms investigated.

2025, Advances in Materials Science and Engineering

The corrosion behavior of high-entropy alloys (HEAs) CoCrFeNi2and CoCrFeNi2Mo0.25was investigated in 3.5 wt. percent sodium chloride (NaCl) at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276) and stainless steel 316L (UNS 31600) to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV) can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS) elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SE...

2025, Journal of Alloys and Compounds

High-entropy alloy fibers with excellent performance potential are desired for functional applications. A previous study on the Al 0.3 CoCrFeNi high-entropy fiber reported a tensile fracture strength of 1200 MPa and elongation of 8% at room temperature (Acta Mater. 123 (2017) 285). The goal of this study is to improve the ductility of Al 0.3 CoCrFeNi high-entropy fiber by manipulating the microstructure through annealing. Al 0.3 CoCrFeNi fibers at F1.0 mm and F1.6 mm diameters were annealed at 900 C for 10 min, 30 min, 300 min and 720 min, respectively. The resulting microstructure is a fine face-centered cubic (FCC) structure with grain sizes less than ~3 mm, which were strengthened by dense NiAl-type ordered body-centered cubic (B2) precipitation. The fibers achieved a fracture strength greater than 900 MPa with an elongation of over 25% at room temperature.

2025, Entropy

In this research, a set of CuNiCrSiCoTi (H-0Nb), CuNiCrSiCoTiNb0.5 (H-0.5Nb) and CuNiCrSiCoTiNb1 (H-1Nb) high-entropy alloys (HEAs) were melted in a vacuum induction furnace. The effects of Nb additions on the microstructure, hardness, and wear behavior of these HEAs (compared with a CuBe commercial alloy) in the as-cast (AC) condition, and after solution (SHT) and aging (AT) heat treatments, were investigated using X-ray diffraction, optical microscopy, and electron microscopy. A ball-on-disc configuration tribometer was used to study wear behavior. XRD and SEM results showed that an increase in Nb additions and modification by heat treatment (HT) favored the formation of BCC and FCC crystal structures (CS), dendritic regions, and the precipitation of phases that promoted microstructure refinement during solidification. Increases in hardness of HEA systems were recorded after heat treatment and Nb additions. Maximum hardness values were recorded for the H-1Nb alloy with measured in...

2025, Advances in Applied Ceramics

Calcium sulfo aluminate cement (CSA) is a promising low CO 2 footprint alternative to Portland cement. The phase assemblage of a commercial CSA cement was investigated by a combination of XRD, SEM-EDX and selective extraction techniques.... more

2025, 2025

Highlights • AlTiNbZrTa RHEAs were prepared via casting and thermomechanical treatments • The RHEAs showed the remarkable specific YS and ductility up to 873 K • Solid solution, second phases, dislocation, and grain refinement rise the... more

2025, Metals

Multiple-basis-element (MBE) alloy was defined as the entropy of mixing over 1R (R is the gas constant, 8.31 J/k), and contains at least three principal elements, each one at over 5%. Thus, MBE alloys can include high-entropy alloys (HEAs), medium-entropy alloys (MEAs), amorphous alloys, and some martensite stainless steels, which have been reported to possess excellent cryogenic properties. This paper reviews the progress of the cryogenic-mechanical properties and applications of MBE alloys. It has been concluded that, with the increase of entropy, the ductile-brittle-transition temperatures (DBTT) can be decreased to the liquid helium temperature (4.2 K). In summary, the cryogenic toughness of MBE alloys can be greatly enhanced by entropy adjustments, which is beneficial to their application at low temperatures.

2025, Metals

The refractory HEAs block material was prepared by powder sintering, using an equal atomic proportion of mixed TiZrNbMoV and NbTiAlTaV metal powder raw materials. The phase was analyzed, using an XRD. The microstructure of the specimen was observed, employing a scanning electron microscope, and the compressive strength of the specimen was measured, using an electronic universal testing machine. The results showed that the bulk cubic alloy structure was obtained by sintering at 1300 °C and 30 MPa for 4 h, and a small amount of complex metal compounds were contained. According to the pore distribution, the formed microstructure can be divided into dense and porous zones. At a compression rate of 10−4s−1, the yield strengths of TiZrNbMoV and NbTiAlTaV alloys are 1201 and 700 MPa, respectively.

2025, Frontiers in Materials

High-entropy alloys (HEAs) open up new doors for their novel design principles and excellent properties. In order to explore the huge compositional and microstructural spaces more effectively, high-throughput calculation techniques are put forward, overcoming the time-consuming and laboriousness of traditional experiments. Here we present and discuss four different calculation methods that are usually applied to accelerate the development of novel HEA compositions, that is, empirical models, first-principles calculations, calculation of phase diagrams (CALPHAD), and machine learning. The empirical model and the machine learning are both based on summary and analysis, while the latter is more believable for the use of multiple algorithms. The first-principles calculations are based on quantum mechanics and several open source databases, and it can also provide the finer atomic information for the thermodynamic analysis of CALPHAD and machine learning. We illustrate the advantages, disadvantages, and application range of these techniques, and compare them with each other to provide some guidance for HEA study.

2025

As ligas metálicas são material amplamente utilizados no nosso dia a dia, desde aplicações simples até sistemas de tecnologia de ponta. Em geral esses materiais são constituídos por ao menos um metal base chamado de solvente e outro elemento químico, que não precisa necessariamente ser um metal, chamado de soluto. Existem vários sistemas de ligas bem conhecidos, tais como: Cu-Zn, Cu-Sn, Cu-Ni, Fe-C, entre outros. No entanto, no início da década de 2000 uma nova classe de ligas com cinco ou mais elementos ganharam destaque por suas propriedades diferenciadas. Esses elementos químicos são distribuídos de forma equimolar e, ao contrário das ligas convencionais, produzem materiais com número reduzidos de fases e com estruturas cristalinas simples. Esses materiais são conhecidos como ligas com múltiplos componentes principais, pois não há um solvente como nas ligas convencionais. Neste trabalho as ligas com múltiplos componentes principais AlCoFeMnNi e AlCoCuFeMnNi foram investigadas para avaliar os efeitos da presença do cobre sobre suas características microestruturais e resistência à corrosão. As ligas foram preparadas por fusão em forno a arco e caracterizadas por medidas de densidade, microscopia óptica e eletrônica de varredura, medidas de dureza, difratometria de raios X, polarização potenciodinâmica, espectroscopia de fotoelétrons excitados por raios X, espectroscopia por dispersão de energias de raios X e espectrometria ótica de emissão atômica com plasma indutivamente acoplado. Os resultados obtidos mostraram que na liga sem presença de cobre apenas uma fase BCC foi detectada, enquanto, com a adição de cobre, duas fases foram observadas: uma FCC e outra BCC. As análises por microscopia eletrônica de varredura e mapeamento por espectroscopia por dispersão de energias de raios X indicaram que a fase FCC é rica em Cu e fase BCC é rica em Fe, ambas com os demais elementos dissolvidos nela. Ao contrário do esperado, a liga AlCoCuFeMnNi mostrou uma melhor resistência à corrosão quando comparada com a liga AlCoFeMnNi. Isso sugere que essa melhora pode estar relacionada à camada de óxido protetivo formada na superfície da liga, e não com a microestrutura dos materiais.

2025, Microscopy and Microanalysis

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

2025, Lecture Notes in Mechanical Engineering

Laser surface alloying is one of the techniques to create high entropy alloy (HEA). HEAs are multi-element solid solution alloys stabilized due to high mixing entropy. These alloys are superior compared to the existing materials used in combustion engines, gas turbine components, and medical implants. The dilution percent is one of the important parameters in laser surface alloying. It has effects on various properties of alloyed components. This paper presents artificial intelligence (AI)-based intelligent model for dilution percent. AI-based model is also compared with a response surface model (RSM). It is observed that RSM is adequate in the modeling of laser surface alloying.

2025, Journal of Materials Engineering and Performance

Due to better alloying characteristics, high-entropy alloys may result in superior surface properties. The present paper investigates the microhardness and erosion behavior of laser surface alloyed Al x Cu 0.5 FeNiTi high-entropy alloy on aluminum alloy (AA1050) substrate. The effects of laser power, scan speed, and powder feed rate on microhardness and erosion rates are studied comprehensively. X-ray diffraction confirms the presence of a three-phase system and a shift in the peak at high power density, which indicates more significant lattice distortion. Scanning electron microscopy images show good dispersion of the threephase system at optimum parameters. Energy dispersive spectroscopy confirms the presence of elements with negligible precipitation. Further, experimental data are used to develop empirical models. The optimizations of these models show an appropriate selection of parameter levels that may result in an erosionresistant alloy. At optimum parameters, microhardness and erosion rate improve by 11.56 and 22.44%, respectively.

2025, Surface and Coatings Technology

AlxCu0.5FeNiTi high entropy alloy coating is synthesized by premixed high purity Cu, Fe, Ni and Ti powders on AA1050 aluminium substrate by laser surface alloying, with the aim to improve microhardness and erosion rate. Phase constituents, microstructure and microhardness were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vickers Microhardness tester, respectively. The erosion behavior of AlxCu0.5FeNiTi coating is checked using an air jet erosion setup. SEM images show presence of three regions. Percentage compositions of these regions are evaluated using Energy Dispersive Spectroscopy. XRD analysis of AlxCu0.5FeNiTi coating confirmed that these regions are a mixture of disordered BCC and two FCC solid solution phases. The microhardness of the AlxCu0.5FeNiTi HEA is 18 times that of the AA1050 aluminium substrate. Results show that AlxCu0.5FeNiTi HEA coating has improved erosion resistance.

2025, materials science and engineering A

The development of high-performance ultraelastic metals with exceptional strength and large elastic strain limits is critical for a wide range of industrial applications, including actuators, medical devices, and high-precision instruments. In this study, a novel strategy is proposed to construct a dual-phase lamellar heterogeneous structure in a CoNiV medium-entropy alloy (MEA) by pre-introducing a precipitated phase prior to cold drawing. This structure, composed of elongated κ phases and an FCC matrix, enables an outstanding combination of an ultrahigh tensile strength (2.6 GPa) and an elastic strain limit of 1.5 %. The cold-drawing performance of the CoNiV MEA containing the brittle κ phase is significantly enhanced by the pronounced twinning-induced plasticity (TWIP) effect and the transformation-induced plasticity (TRIP) effect (κ → FCC). The dual-phase lamellar structure effectively disperses cracks and delays stress concentration, contributing to high crack tolerance. Meanwhile, the presence of high dislocation density, fine grain size, residual κ phases, and various nanoscale defects imparts the alloy with exceptional strength. This work innovatively addresses the general limitation of elastic strain in high-strength materials through multi-phase structural design, offering new theoretical insights and a design paradigm for the development of advanced metallic materials with superior strength and elastic deformability.

2025, Metals

In recent years, high-entropy materials (HEMs) have garnered significant a ention due to their unique multi-principal element compositions, which endow them with remarkable properties distinct from traditional materials. The order and disorder in HEMs are particularly complex, influenced by factors such as temperature, pressure, and composition, and are closely related to their mechanical and physical properties. This review systematically summarizes the progress in understanding the order and disorder in HEMs, with a focus on the role of data science in this field. We introduce the basic concepts of order and disorder and the related research in HEMs, discuss the nonlinear behaviors of HEMs, and elaborate on the relevant applications of data science, including analysis by machine learning, molecular dynamics simulations, and Monte Carlo simulations. Challenges and future directions are also explored, aiming to provide comprehensive insights into materials science.

2025

This study investigates the impact of 0.25 wt% B4C addition on the microstructure, phase stability, and mechanical properties of metastable Fe40Mn20Co20Cr15Si5 (at.%) high-entropy alloys (HEAs) fabricated via laser powder bed fusion (LPBF). A comparative analysis between B4C-containing (BC) and B4C-free (CS) alloys explored the influence of varying LPBF parameters. Electron backscattered diffraction (EBSD) revealed a strong dependence of microstructure on laser power and scanning speed in CS alloys, with significant variations in grain size and morphology. Conversely, BC alloys exhibited enhanced microstructural stability, indicating a more robust grain growth mechanism due to the influence of B4C. B4C addition also promoted grain refinement and stabilized the γ-f.c.c. phase. Mechanical testing showed a substantial increase in yield strength (YS) from 508 MPa (CS) to 670 MPa (BC) and a moderate increase in ultimate tensile strength (UTS) from 843 MPa (CS) to 854 MPa (BC). However, ductility decreased from 25 % to 5 %. Critically, synchrotron X-ray diffraction revealed deviations from the ideal c/a ratio (1.633) for both alloys. CS alloys showed an increase in c/a ratio after tensile deformation, indicative of a deformation-induced phase transformation, while BC alloys exhibited a decrease, suggesting a distinct deformation mechanism. This novel observation provides key insights into the role of B4C in controlling the deformation behavior of this HEA.

2025, Journal of Materials Research and Technology

The characteristics of dynamic recrystallization (DRX) of a CoCrFeMnNi higheentropy alloy (HEA) was investigated via hot compression testing in the temperature range 950e1100 C and at true strain rates of 10 À2 and 10 À1 s À1 . The discontinuous DRX was found to be the dominant mechanism corroborating the microstructural evolution. The progress of the initiation of DRX was investigated in terms of critical strain/stress required using the Poliak eJonas analytical criterion. Consequently, a new kinetic model based on Avramietype function was established for the HEA to predict the DRX fractional recrystallization. It was revealed that the volume fraction of DRX grains increased with increasing strain. In the case of 10 À2 s À1 , steadyestate flow was achieved after the completion of one DRX process cycle resulting in further straining, leading to the occurrence of dynamic restoration processes involving formation of substructures and generation and annihilation of dislocations inside the DRX grains which effectively increased the fraction of partially deformed DRX (substructured) grains. A good agreement between the proposed DRX kinetics model and microstructure observation results validated the accuracy of DRX kinetics model for CoCrFeMnNi HEA. The preferred orientation of the nonerecrystallized grains was towards the formation of <101> fiber texture, whereas a random microetexture is revealed in the recrystallized grains.

2025, Journal of the Japan Society of Powder and Powder Metallurgy

High entropy alloys (HEAs) and medium entropy alloys (MEAs) are new classes of materials, defined as alloys composed of five or more and four or fewer kinds, respectively, of alloying elements with (near-)equiatomic concentrations. In the present article, we reviewed our recent works on ultra-grain refinement of HEAs and MEAs. CoCrFeMnNi HEA and its sub-system MEAs were highly deformed by high-pressure torsion and subsequently annealed under various conditions to obtain fully-recrystallized microstructures with FCC single phase having different mean grain sizes. It was found that ultrafine-grained (UFG) microstructures could be easily obtained by simple thermomechanical processes. Grain size and chemical composition dependence on mechanical properties of the HEA and MEAs were evaluated by tensile tests at room temperature. UFG HEAs and MEAs exhibited characteristic phenomena, such as discontinuous yielding and extra-hardening, similar to other UFG metals. In addition, the UFG HEAs and MEAs showed better strength-ductility balance compared with conventional UFG metals. Friction stresses of HEAs and MEAs were determined from Hall-Petch relationships and found to be much higher than those of pure metals and dilute alloys having FCC structure. Analysis based on theoretical models suggested that the high friction stress reflected atomic-scale heterogeneity in HEAs and MEAs.

2025, Journal of Alloys and Compounds

The design and development of single phase multi-component high entropy alloy (HEA) using conventional hit and trial method is a challenging job due to the large number of experimental trials required to find the right alloy composition from possible combinations of various alloying elements in the multicomponent system. Present investigation reports a novel CALculation of PHAse Diagram (CALPHAD) based approach, which can significantly reduce number of experimental trials in a very time effective manner to find single phase HEAs. Here, 1287 equiatomic five-component alloy systems were studied using both parametric and CALPHAD approaches to find single phase fcc and bcc HEAs. The parametric approach reduced the number of trials to 124 whereas; CALPHAD approach reduced the number of alloy compositions to 10. Further, the experimental investigation on the 10 alloy systems reveals that six of them form single phase HEAs. In addition, Thermo-Calc software was also used effectively to draw the isothermal pseudo ternary sections at 1000 K varying all constituents elements from 5 to 35 atomic percent for the CoCuFeMnNi alloy system. Experimental evidences confirmed that the isothermal pseudo ternary diagrams are very useful to design non equiatomic single phase as well as multiphase HEAs in the absence of phase diagram for the five component systems.

2025, Journal of Alloys and Compounds

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2025, Materials & Design

Combinatorial approach has been employed to understand the deformation micro-mechanisms and strength evolution of FCC equiatomic CoCuFeMnNi high entropy alloy using equimolar subset alloys, judiciously unearthed by thermodynamic modelling using CALPHAD. A series of mechanical tests indicate absence of one-to-one correlation between entropy of mixing and mechanical properties for the alloys. Optimum combination of strength and ductility was observed in ternary equiatomic FeMnNi alloy, although quinary alloy exhibits the highest strength among all the four alloys. The deformation of all the alloys is dominated by octahedral slip as well as partial slip with the absence of deformation twinning. TEM investigation on the deformed samples reveals profuse dislocation activity. Strain rate sensitivity in the range of 0.005-0.008 and activation volume of 100-150 b 3 indicate cross slip as the dominant operative mechanism for all the alloys. Nevertheless, quinary CoCuFeMnNi HEA manifests unique behavior by showing increase in strength even after long term annealing at 1273 K for 7 days. This is attributed to the presence of copper-rich nano-clusters in the alloy which undergo coarsening and partial dissolution thereby contributing to higher solid solution strengthening. Thus, the unique microstructure of the quinary CoCuFeMnNi HEA that can explore cluster strengthening and solid solution hardening manifests new vistas to design novel alloys for potential applications.

2025, International Journal of Fatigue

2025, Journal of Alloys and Compounds

Single phase BCC structure (space group Im m) TEM micrograph of alloy and selected area diffraction pattern indicating grains with BCC structure. Large temperature range (700-2600 K), for stability of BCC single phase 54 Non-equiatomic... more

2025, General Corrosion

An experiment to study the effect of sea water on different samples of steel was conducted. Samples of steel-U8 (St-U8), steel-45 (St-45) and alpha-Iron (α-Fe) were immersed in a 3% molar solution of Sodium chloride (NaCl) prepared in the laboratory and their changes in mass studied for a certain period at room temperature. From comparison of the corrosion rates for the steel samples, it was found out that steel-45 is more likely to undergo corrosion faster than steel-U8.

2025, Nature Communications

High-Entropy Alloys (HEAs) are a new family of crystalline random alloys with four or more elements in a simple unit cell, at the forefront of materials research for their exceptional mechanical properties. Their strong chemical disorder leads to mass and force-constant fluctuations which are expected to strongly reduce phonon lifetime, responsible for thermal transport, similarly to glasses. Still, the long range order would associate HEAs to crystals with a complex disordered unit cell. These two families of materials, however, exhibit very different phonon dynamics, still leading to similar thermal properties. The question arises on the positioning of HEAs in this context. Here we present an exhaustive experimental investigation of the lattice dynamics in a HEA, Fe20Co20Cr20Mn20Ni20, using inelastic neutron and X-ray scattering. We demonstrate that HEAs present unique phonon dynamics at the frontier between fully disordered and ordered materials, characterized by long-propagating...

2025, Journal of the Indian Institute of Sciences

The strength-ductility trade-off is an eminent factor in deciding the mechanical performance of a material with regard to specific applications. The strength-ductility synergy is generally inadequate in as-synthesized high entropy alloys (HEAs); however, it can be tailored owing to its tunable microstructure and phase stability. Thermomechanical processing (TMP) allows the microstructure to be tailored to achieve desired strength-ductility combination. The additional attribute is evolution of texture, which also significantly influences the mechanical properties. This review presents a critical insight into the role of TMP to achieve superior strength-ductility symbiosis at room temperature in single-phase (FCC, BCC) and multiphase HEA. The role of overall processing strategy of HEAs encompassing rolling and subsequent annealing in relation to the evolution of microstructure and texture in have been discussed. Recently practiced severe plastic deformation processes have also shown promise in improving the strength-ductility combination. The relevance of these processes in the processing of HEAs has also been analysed. At the end, futuristic approaches have been elaborated to enable efficient as well as hassle-free process towards achieving the proficiency of strength-ductility in HEAs.

2025

The objective of the present study was to investigate the cold deformation texture and annealing texture in pure Zinc (Zn). As-cast pure Zn was subjected to cryo-rolling of 90% reduction in thickness followed by annealing at 50 o C for different soaking times of 5 min, 10 min, 20 min and 30 min respectively. The texture and microstructure evolution during cryorolling and subsequent annealing of these samples were characterized through X-ray diffraction (XRD) and electron backscattered diffraction (EBSD). A dominant 1120   fiber texture was observed in both the rolled and annealed samples. However, the texture intensity was increased till 10 min of soaking time and it was then decreased on further increasing the soaking time. Only {1012} type tensile twins were observed in the samples and these twinning was found to be significant in all the samples. The Vickers hardness of the samples was increased till 10 min of annealing time followed by a decrease in hardness on further increas...

2025, arXiv (Cornell University)

High-entropy alloys and ceramics containing at least five principal elements have recently received high attention for various mechanical and functional applications. The application of severe plastic deformation (SPD), particularly the high-pressure torsion (HPT) method, combined with the CALPHAD and first-principles calculations resulted in the development of numerous superfunctional high-entropy materials with superior properties compared to the normal functions of engineering materials. This article reviews the recent advances in the application of SPD to developing superfunctional high-entropy materials. These superfunctional properties include (i) ultrahigh hardness levels comparable to the hardness of ceramics in high-entropy alloys, (ii) high yield strength and good hydrogen embrittlement resistance in high-entropy alloys; (iii) high strength, low elastic modulus, and high biocompatibility in high-entropy alloys, (iv) fast and reversible hydrogen storage in high-entropy hydrides, (v) photovoltaic performance and photocurrent generation on high-entropy semiconductors, (vi) photocatalytic oxygen and hydrogen production from water splitting on high-entropy oxides and oxynitrides, and (vii) CO2 photoreduction on high-entropy ceramics. These findings introduce SPD as not only a processing tool to improve the properties of existing high-entropy materials but also as a synthesis tool to produce novel high-entropy materials with superior properties compared with conventional engineering materials. Keywords: multi-principal element alloys (MPEAs); high-entropy alloys (HEAs); high-entropy ceramics (HECs); high-entropy oxides (HEOs); ultrafine-grained (UFG) microstructure; highpressure torsion (HPT).

2025, Journal of The Electrochemical Society

The majority of studies on high-entropy alloys are focused on their phase, microstructure, and mechanical properties. However, the physical properties of these materials are also encouraging. This paper provides a brief overview of the... more

2025, arXiv (Cornell University)

2025, Karlsruhe Institute of Technology (KIT), IPEK - Institute of Product Engineering, Karlsruhe, DE

1-Nitriding treatment on GX40 plate produced important layer of oxidation, and initiation of adhesive wear was noticed. But the diffusion layer and some hardening effect were still present and efficient. This “prime-path” for 800°C (T1T 830°C) in terms of wear should be considered carefully regarding oxidation.
2-“Ceramic” Zr-Ti thermal sprayed coating on plates and Al-diffusion treatment on pin showed good behaviour, encouraging for both of those “preferred options” at 850°C (T1T 860°C).

2025, Materials Science and Engineering: A

The work-hardening mechanisms of two novel advanced high-strength steels (Fe 67.4-x Cr 15.5 Ni 14.1 Si 3.0 B x [x = 0 (0B), 2 (2B)] wt%) were investigated by means of field emission gun scanning electron microscopy coupled with angle-selective backscattered detection, transmission electron microscopy, and electron backscattered diffraction. The 0B and 2B specimens combined low yield stresses and high ultimate tensile strengths with good total elongation percentages, with results of 219 MPa, 568 MPa, and 83% and 357 MPa, 703 MPa, and 42%, respectively. The 0B and 2B alloys were characterized by a decreasing work hardening rate, followed by a constant and finally a steep decreasing change tendency. Detailed angle-selective backscattered and electron backscattered diffraction microscopy observations on interrupted tensile test specimens revealed that the work hardening rate in these alloys was facilitated by planar (extended stacking faults) and wavy (dislocation cell and wavy microbands) characteristics and mechanical nano-twins. The total flow stresses of the 0B and 2B specimens were calculated from the dislocation density and twin spacing. This indicated that the work hardening contribution of the microband mechanism can be estimated via a dislocation hardening formula. The rule of mixture was also used to evaluate the effect of a boron addition on the total flow stress of the 2B specimen; this illustrated that, in addition to the strengthening contribution of the second hard phase to the yield stress, the rule of mixture must also be considered. The calculated values of the contribution of the mechanical nano-twins and dislocations on the work-hardening for 0B and 2B specimens were about 62% and 18.6% and 52% and 31.8%, respectively.

2025, IJSES

High-entropy alloys (HEAs) represent an advanced class of metallic materials that differ from conventional alloys by consisting of four or more principal elements in nearly equal proportions. This unique composition leads to a significant increase in configurational entropy, resulting in exceptional mechanical and physical properties such as high hardness, excellent thermal stability, and superior corrosion resistance. HEAs typically exhibit either a body-centered cubic (BCC) structure, which provides high strength but low ductility, or a face-centered cubic (FCC) structure, which offers enhanced plasticity but lower strength. In this study, a Cu-Fe-Ni-Co high-entropy alloy (HEA) composite was fabricated using the powder metallurgy technique. The elemental powders were ball-milled for 30 hours to ensure uniform mixing, followed by cold pressing at 400 MPa. The green compact was then sintered at 1250°C for 60 minutes. The fabricated sample was evaluated for density, microstructure, hardness, and compressive strength. The results revealed a 96% relative density, with microstructural analysis indicating a singlephase structure. The sample exhibited a hardness of 200 HV.

2025, Microscopy and Microanalysis

2025, Materials Chemistry and Physics

2025, Entropy

High-entropy alloys (HEAs) are a new class of solid-solution alloys that have attracted worldwide attention for their outstanding properties. Owing to the demand from transportation and defense industries, light-weight HEAs have also garnered widespread interest from scientists for use as potential structural materials. Great efforts have been made to study the phase-formation rules of HEAs to accelerate and refine the discovery process. In this paper, many proposed solid-solution phase-formation rules are assessed, based on a series of known and newly-designed light-weight HEAs. The results indicate that these empirical rules work for most compositions but also fail for several alloys. Light-weight HEAs often involve the additions of Al and/or Ti in great amounts, resulting in large negative enthalpies for forming solid-solution phases and/or intermetallic compounds. Accordingly, these empirical rules need to be modified with the new experimental data. In contrast, CALPHAD (acronym of the calculation of phase diagrams) method is demonstrated to be an effective approach to predict the phase formation in HEAs as a function of composition and temperature. Future perspectives on the design of light-weight HEAs are discussed in light of CALPHAD modeling and physical metallurgy principles.