High-entropy Alloys Research Articles

A semi-analytic universal model on elasticity across wide temperatures and pressures.

A semi-analytic model is presented universally for the elastic constants and moduli of solid phases in a wide range of temperatures and pressures. We derive in detail the model as a function of temperature and pressure, where the characteristic temperature is clearly associated with the Debye temperature. The abundant experiments of thermal elasticity for Cr-Mn-Fe-Co-Ni high entropy alloys are used to estimate the validity of the characteristic temperature of elasticity. The linear process of the analytical part significantly reduces the high computational and experimental cost of elasticity across a wide range of temperatures and pressures. We take the elastic property of beryllium within the range of up to 6000K and 500GPa as a prototype to investigate the accuracy, efficiency and extrapolation of this model. The application to Mg3Al2Si3O12-pyrope and CaSiO3-perovskite in the Earth's mantle further suggests that our model excellently describes the elasticity of different materials across a wide range of temperatures and pressures.

A ZnFeNiCoCr high-entropy alloy for efficient bifunctional oxygen electrocatalysis

A ZnFeNiCoCr high-entropy alloy for efficient bifunctional oxygen electrocatalysis

A multi-scale constitutive model for analyzing the tensile deformation of eutectic high-entropy alloys

A multi-scale constitutive model for analyzing the tensile deformation of eutectic high-entropy alloys

Cocktail effect on superconductivity in hexagonal high-entropy alloys

Cocktail effect on superconductivity in hexagonal high-entropy alloys

Synthesis Framework for Designing PtPdCoNiMn High-Entropy Alloy: A Stable Electrocatalyst for Enhanced Alkaline Hydrogen Evolution Reaction.

High entropy alloys (HEAs) are an emerging class of advanced materials characterized by their multifunctionality and potential to replace commercial catalysts in electrocatalytic water splitting. The synergy among the various alloyed elements in HEAs makes them particularly promising for applications in electrocatalysis. However, preparation of HEA via bottom-up approaches by avoiding the formation of mono, di, and tri metallic alloys in the nanoscale is challenging. This aspect is addressed, in this study by exploring the logical selection of solvents, reducing agents, and capping agents, along with their relative fractions, in the solvothermal synthesis of the HEA comprising platinum-palladium-cobalt-nickel-manganese (PtPdCoNiMn). It is established that the reducing capabilities of both the solvent and reducing agent are crucial for the reduction of each metal to form a single-phase HEA. The synthesized HEA (20 wt.%)/functionalized carbon (FC) demonstrates excellent performance as an HER catalyst, exhibiting a low overpotential of 48.7mV at -10 mA cm-2 in an alkaline electrolyte. This performance is characterized by high reaction kinetics and stability at elevated current densities. Furthermore, the catalyst shows impressive performance in both simulated and actual seawater. This development reduces the reliance on platinum while enhancing the long-term durability and catalytic efficiency of the electrocatalyst.

Molecular Dynamics Simulations of Micromechanical Behaviours for AlCoCrFeNi2.1 High Entropy Alloy during Nanoindentation

Molecular Dynamics Simulations of Micromechanical Behaviours for AlCoCrFeNi2.1 High Entropy Alloy during Nanoindentation

Superior bonding of Al/Mg interface by introducing nanocrystals via high-entropy alloy coating and ultrasonic vibration

Superior bonding of Al/Mg interface by introducing nanocrystals via high-entropy alloy coating and ultrasonic vibration

Preparation and Properties of Cu-Containing High-entropy Alloy Nitride Films by Magnetron Sputtering on Titanium Alloy

Preparation and Properties of Cu-Containing High-entropy Alloy Nitride Films by Magnetron Sputtering on Titanium Alloy

Mechanical and Tribological Properties of (AlCrNbSiTiMo)N High-Entropy Alloy Films Prepared Using Single Multiple-Element Powder Hot-Pressed Sintered Target and Their Practical Application in Nickel-Based Alloy Milling

Mechanical and Tribological Properties of (AlCrNbSiTiMo)N High-Entropy Alloy Films Prepared Using Single Multiple-Element Powder Hot-Pressed Sintered Target and Their Practical Application in Nickel-Based Alloy Milling

Structure and properties of Fe40Mn20Cr20Ti10Al10 high-entropy alloy fabricated by mechanical alloying and spark plasma sintering

Structure and properties of Fe40Mn20Cr20Ti10Al10 high-entropy alloy fabricated by mechanical alloying and spark plasma sintering

Engineering Topological and Chemical Disorder in Pd Sites for Record-Breaking Formic Acid Electrocatalytic Oxidation.

Designing palladium-based formic acid oxidation reaction (FAOR) catalysts to achieve significant breakthroughs in catalytic activity, pathway selectivity, and toxicity resistance is both urgent and challenging. Here, these challenges are addressed by pioneering a novel catalyst design that incorporates both topological and chemical disorder, developing a new class of PdCuLaYMnW high-entropy amorphous alloys with a porous network (Net-Pd-HEAA) as a highly active, selective, and stable FAOR electrocatalyst. This novel Net-Pd-HEAA demonstrates record-breaking FAOR performance, achieving the mass and specific activities of 5.94 A mgPd -1 and 8.94mA cm-2, respectively, surpassing all previously reported Pd-based catalysts and showing strong competitiveness against advanced Pt-based catalysts. Simulataneously, Net-Pd-HEAA exhibits extraordinary stability in accelerated durability tests (ADT) and chronoamperometry (CA) tests. Advanced characterization and in situ, spectral analysis reveal that the extremely disordered atomic structure effectively regulates the geometric and electronic structure of the Pd sites, enhancing active intermediate coverage, facilitating dehydrogenation pathway, and inhibiting the production/adsorption of CO. Furthermore, when employed as the anode catalyst in proton exchange membrane water electrolysis (PEMWE), Net-Pd-HEAA only requires a potential of 1.28V to obtain a current density of 1 A cm-2, and operates stably in a highly corrosive electrolyte for over 100 h.

Data-driven design of novel lightweight refractory high-entropy alloys with superb hardness and corrosion resistance

AbstractLightweight refractory high-entropy alloys (LW-RHEAs) hold significant potential in the fields of aviation, aerospace, and nuclear energy due to their low density, high strength, high hardness, and corrosion resistance. However, the enormous composition space has severely hindered the development of novel LW-RHEAs with excellent comprehensive performance. In this paper, an machine learning (ML)-based alloy design strategy combined with a multi-objective optimization method was proposed and applied for a rational design of Al-Nb-Ti-V-Zr-Cr-Mo-Hf LW-RHEAs. The quantitative relation of “composition-structure-property” was first established by ML modeling. Then, feature analysis reveals that Cr content greater than 12 at.% is a key criterion for alloys with high corrosion resistance. The phase structure, density, melting point, hardness and corrosion resistance of the alloys were screened layer by layer, and finally, three LW-RHEAs with superb hard and corrosion resistance were successfully designed. Key experimental validation indicates that three target alloys have densities around 6.5 g/cm3, and all alloys are disordered bcc_A2 single-phase with the highest hardness of 593 HV and the largest pitting potential of 2.5 VSCE, which far exceeds all the literature reports. The successful demonstration in this paper clearly demonstrates that the present design strategy driven by the ML technique should be generally applicable to other RHEA systems.

High entropy alloy reinforcement for superior electromagnetic interference shielding performance in carbon fiber‐reinforced polymer composites

AbstractThis study explores the enhancement of electromagnetic interference (EMI) shielding effectiveness (SE) in carbon fiber‐reinforced polymer (CFRP) composites through the integration of equatomic CoCuFeNi high entropy alloy (HEA) particles. Employing mechanical alloying (MA), CoCuFeNi HEA powders were synthesized, revealing a face‐centered cubic structure with crystallite and particle sizes of 14.7 nm and 11.62 μm, respectively. The integration of these HEA particles at concentrations of 5%, 10%, and 15% by weight into epoxy resin, followed by the fabrication of composites using the hand lay‐up technique. Detailed structural analysis of HEA particles confirmed the successful synthesis of equatomic HEAs via MA. Structural analysis of the HEA integrated composites revealed vacancy regions at 5% concentration, a uniform distribution at 10%, and particle agglomeration causing inhomogeneity and vacancies at 15%. The composites demonstrated significant improvements in EMI SE, with the 10% HEA sample showing superior performance compared to the other samples. Specifically, the 10% HEA composite achieved a peak SE of 73.09 dB at 4.72 GHz, attributed to the optimized distribution of HEA particles that enhanced electrical conductivity and reflective properties.Highlights CoCuFeNi HEA particles were successfully synthesized via MA. HEA particles were added to epoxy at 5, 10, and 15 wt% for composite fabrication. Voids were observed in HEA5, uniformity in HEA10, and clustering in HEA15. EMI shielding was assessed using VNA, SE, dielectric permittivity, and magnetic permeability. The HEA10 composite achieved peak EMI shielding, 73.09 dB at 4.72 GHz.

Wear Resistance of N-Doped CoCrFeNiMn High Entropy Alloy Coating on the Ti-6Al-4V Alloy

Wear Resistance of N-Doped CoCrFeNiMn High Entropy Alloy Coating on the Ti-6Al-4V Alloy

Synthesis of AlCrFeMnX-based high-entropy alloys using powder metallurgy and their investigation through thermodynamic perspective

Synthesis of AlCrFeMnX-based high-entropy alloys using powder metallurgy and their investigation through thermodynamic perspective

Phase Stability, Structural Properties, Electronegativity, Mechanical Properties, and Neutron and Gamma-Ray Attenuation Properties of Cantor High Entropy Alloys for Advanced Nuclear Applications

Phase Stability, Structural Properties, Electronegativity, Mechanical Properties, and Neutron and Gamma-Ray Attenuation Properties of Cantor High Entropy Alloys for Advanced Nuclear Applications

Homogenization Heat Treatment of CoCrCuMnNi High-Entropy Alloys: Limitations and Challenges

Homogenization Heat Treatment of CoCrCuMnNi High-Entropy Alloys: Limitations and Challenges

Microstructure and Wear Behavior of AlxCoCuNiTi (x = 0, 0.4, and 1) High-Entropy Alloy Coatings

AlxCoCuNiTi (x = 0, 0.4, and 1) high-entropy alloy coatings on 45 steel substrates were prepared by laser cladding, and their phase structure, microstructure, element partition, and wear behavior were investigated. The results show that the AlxCoCuNiTi (x = 0, 0.4, and 1) coatings have a dual-phase structure of FCC and BCC. With the increase of x from 0 to 1, the content of the FCC phase decreases from 66.9 wt.% to 14.3 wt.%, while the content of the BCC phase increases from 33.1 wt.% to 85.7 wt.%. When x = 0.4, the lattice constants of the two phases are the largest, and their densities are the smallest. The microstructure of the AlxCoCuNiTi (x = 0, 0.4, and 1) coatings is composed of BCC-phase dendrites and FCC-phase interdendrite regions. Ti is mainly enriched in the primary phase or BCC dendrites, Cu is enriched in the interdendrite regions, and Al is enriched in the dendrites. The friction coefficients of AlxCoCuNiTi (x = 0, 0.4, and 1) coatings during wear tests are 0.691, 0.691, and 0.627, respectively. The lowering of the wear friction coefficient when increasing the Al content is mainly related to the change in phase structure, microstructure, and wear mechanism.

Bayesian Learning Aided Theoretical Optimization of IrPdPtRhRu High Entropy Alloy Catalysts for the Hydrogen Evolution Reaction.

The complex compositional space of high entropy alloys (HEAs) has shown a great potential to reduce the cost and further increase the catalytic activity for hydrogen evolution reaction (HER) by compositional optimization. Without uncovering the specifics of the HER mechanism on a given HEA surface, it is unfeasible to apply compositional modifications to enhance the performance and save costs. In this work, a combination of density functional theory and Bayesian machine learning is used to demonstrate the unique catalytic mechanism of IrPdPtRhRu HEA catalysts for HER. At high coverage of underpotential-deposited hydrogen, a d-band investigation of the active sites of the HEA surface is conducted to elucidate the superior catalytic performance through electronic interactions between elements. At low coverage, a novel Bayesian learning with oversampling approach is then outlined to optimize the HEA composition for performance improvement and cost reduction. This approach proves more efficacious and efficient and yields higher-quality structures with less training set bias compared with neural-network optimization. The proposed HEA optimization theoretically outperforms benchmark Pt catalysts' overpotential by ≈40% at a 15% reduced synthesis cost comparing to the equiatomic ratio HEA.

Influence of Cu and Co addition on metallurgical and wear characteristics of AlCrFeNi high entropy alloy

The creation of new alloys with improved qualities has become essential in modern industries for high-performance materials. This work’s main objective is to use vacuum arc melting (VAM) to synthesize two different high-entropy alloys (HEAs): AlCrFeNiCu and AlCrFeNiCo. The mechanical properties, phase composition, grain boundaries, and alloy composition of the HEAs were studied. The predominant crystal structure, the Body-Centred Cubic (BCC) phase was obtained for both alloys. Significantly, the Co-containing HEA showed a smaller particle size than the Cu-containing HEA, which led to a 14.21% increase in microhardness. It indicates that the Co-based HEA will likely perform better than the Cu-based HEA in applications prone to abrasion, and indentation, and requiring high hardness levels based on the observed microstructure and hardness parameters. According to wear surface morphology studies, main effects analysis and ANOVA show that increasing loads and sliding distances increase wear rate, whereas sliding velocity has less effect. The best wear rate-reducing parameters are 10 N, 0.5 m/s, and 500 m for Cu-containing HEAs, and the same can be predicted using regression analysis. The study categorizes the intricate worn surface structure by describing different surface properties and wear mechanisms, such as grooves, delamination, adhesive wear, and pitting.