High-entropy Alloy Particles Research Articles

Ensemble machine learning for predicting and enhancing tribological performance of Al5083 alloy with HEA reinforcement

This study investigates the tribological behavior of Al5083 alloy reinforced with AlCoCrFeNiSi high-entropy alloy (HEA) particles using friction stir processing (FSP). Wear characteristics were analyzed using pin-on-disc experiments across varying HEA volume percentages, disc speeds, and test durations, revealing significant improvements in wear resistance with increasing HEA content. Machine learning techniques, including artificial neural networks (ANN) and long short-term memory (LSTM) networks, were employed to predict specific wear rate (SWR) and coefficient of friction (COF) with high accuracy. The ensemble model combining ANN and LSTM architectures achieved R-squared values of 0.9653 for SWR and 0.9718 for COF, with a root mean square error (RMSE) of 0.024 and 0.017 for SWR and COF respectively, indicating robust predictive capabilities. Cross-validation further validated the model's effectiveness, achieving an average prediction error of 2.13% for SWR and 1.89% for COF. Response surface methodology (RSM) optimization refined process parameter relationships, identifying conditions that minimize SWR to 3.57 × 10–6 mm³/Nm and COF to 0.237. Scanning electron microscopy (SEM) analysis of worn surfaces confirmed the effectiveness of HEA reinforcement in mitigating wear mechanisms, enhancing the material's durability by 45% compared to the unreinforced alloy. This comprehensive approach advances the understanding of HEA-reinforced composites. It provides practical insights for optimizing material performance in industrial applications, contributing to developing high-performance materials tailored for durability and wear resistance.

Tribological characterization of high entropy alloy particles reinforced aluminum matrix composites at room and cryogenic temperatures

Tribological characterization of high entropy alloy particles reinforced aluminum matrix composites at room and cryogenic temperatures

Nanofibers decorated with high-entropy alloy particles for the detection of nitrites.

Excessive residues of nitrite can pose a serious threat to human health, making the establishment of an efficient and effective electrochemical sensor for nitrite detection highly necessary. Herein, we report on a sensor based on nitrogen-doped carbon nanofibers, with FeCoNiCuAl high-entropy alloy (HEAs) nanoparticles in situ grown on the carbon fibers through a confinement effect. The FeCoNiCuAl/CNF sensor is capable of electrochemically detecting nitrite using both differential pulse voltammetry (DPV) and amperometric (I-t) methods. The DPV detection offers a linear range of 0.1-5000 μM and 5000-18 000 μM, with sensitivities of 150.6 μA mM-1 cm-2 and 80.1 μA mM-1 cm-2 and a detection limit of 0.023 μM (S/N = 3). The I-t detection covers a range of 1-10 000 μM, with a sensitivity of 337.84 μA mM-1 cm-2 and a detection limit of 0.12 μM. Moreover, the sensor exhibits excellent anti-interference properties, stability, and reproducibility, providing feasibility for nitrite detection in real-world environments.

Achieving superior strength-ductility combination in the heterogeneous microstructured Ti64 alloy via multi-eutectoid elements alloying with CoCrFeNiMn during laser powder bed fusion

ABSTRACT The formation of coarse needle-shaped α′-Ti within columnar β-Ti grains in additively manufactured titanium alloy components is nearly unavoidable, and it can lead to unforeseeable service failures. This study employs a multi-component eutectoid alloying strategy, integrating CoCrFeNiMn high-entropy alloy particles within Ti64 alloy. By varying laser parameters, the resulting microstructure transitions from β-dominated to a metastable β + nanoscale α′ microstructure. The coarse needle-shaped α′-Ti and columnar β-Ti grains are significantly refined. Concurrently, the multi-component eutectoid alloying strategy successfully suppresses the formation of detrimental intermetallic compounds by promoting the uniform distribution and solubility of the alloying elements. The Ti64-(4.5%) CoCrFeNiMn alloy demonstrates exceptional mechanical properties, including high tensile strength (1333.8 MPa), uniform elongation (9.3%), and a work-hardening capacity (>390.0 MPa). These are attributed to the continuous variation of Co, Cr, Fe, Ni, and Mn concentrations within the ultrafine α′ and metastable β-phase regions, providing a progressive transformation-induced plasticity effect.

Fabrication and characterization of Al alloy composites reinforced with nanocrystalline Al4CrFeMnTi0.25 high-entropy alloy particles via double ultrasonic stir casting for aerospace applications

The aim of the present work is to fabricate the Al alloy-based composites by using a new class of High Entropy Alloy (HEA) reinforcement particles for aerospace applications, addressing the limitations associated with traditional ceramic reinforcement particles. Therefore, the present work is to fabricate an Al-7150 alloy-based composite by incorporating a novel nanocrystalline Al4CrFeMnTi0.25 HEA (NCHEA) reinforcing particle (0.5, 1, 1.5 and 2 wt%) through a double ultrasonic two-step stir casting technique. The relative density decreases with the addition of NCHEA particles in the mixture, however, the porosity remains below 5 % due to double ultrasonication. The grain size was significantly refined with the addition of NCHEA particles. The AA7150-HEA composite exhibits a “stone in mud” structure in which the HEA particles (stone) are embedded in an aluminum matrix (mud) due to the high density of NCHEA reinforcement. The AA7150–1.5 wt% HEA composite exhibited a small average crystallite size of 27.03 nm and a maximum dislocation density of 2.67 nm-2 analysed by X-Ray Diffraction (XRD) analysis. The AA7150–1.5 wt% HEA alloy achieved a maximum Vickers microhardness of 214.49 HV and an ultimate tensile strength of 218.37 MPa, which were 37 % and 27.5 % higher, respectively, compared to the base Al-7150 alloys. Failure usually occurs at the interface where the alloy is bonded to the ceramic reinforcement, however, in the HEA-reinforced composite, this fall-off action does not occur as observed by fractographic analysis. Nonetheless, Al7150–2wt% HEA-composites have many cracks on the fractured surface due to the agglomeration of NCHEA particles in composite. The NCHEA reinforcement particles can be incorporated into the Al7150 matrix as an alternative to ceramic reinforcements, enabling enhanced strength improvement.

Microstructure, mechanical, and wear characteristics of heat-treated aerospace-grade aluminium composite reinforced with HEA particles

This research paper investigates the mechanical, microstructural, and wear characteristics of Al7075 composite reinforced with high entropy alloy particles. Stir casting, equipped with an ultrasonic probe, was used for the fabrication of the composite. Microstructural analysis including optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and X-ray diffraction, was conducted assess the microstructure and dispersion of reinforced particles in the composite and alloy. Results indicated that hardness and tensile strength increased with higher weight percentages of reinforcement, while percentage elongation decreased. However, properties decreased with further reinforcement beyond 6 wt% in the composite. Mechanical testing revealed that heat treated composites with 6.0 wt% HEAp have maximum UTS and hardness of 287.6 MPa and 117.2 HRB, respectively. Fracture morphology analysis further provides insights into the interactions between the HEAp and the aluminium matrix, shedding light on crack initiation, propagation, and the role of HEAp in influencing the fracture mechanisms. A comprehensive examination of the worn surface was conducted using SEM and an optical profilo-meter.

Implications of incorporating CrFeNiTiZn high-entropy alloy on the tribomechanical and microstructure morphology behaviour of A356 composites processed by friction stir processing

Abstract This study investigated the impact of incorporating a CrFeNiTiZn High Entropy Alloy (HEA) into the A356 aluminum matrix through the friction stir processing (FSP) technique. The CrFeNiTiZn HEA, renowned for its compositional complexity and high-performance potential, was incorporated into the A356 alloy with different weight percent combinations to enhance its mechanical and tribological characteristics. The results revealed a refined microstructure characterized by solid solution phases and potential intermetallic compound formation due to the HEA addition for A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composition. Strong interfacial bond strength was also observed among the matrix and reinforcement particles for the A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composition. The number of grains was found to be about 1820.34 (average grain size is 686 µm) for A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn processed composite with FSP per square inch at 500 magnifications. The A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composite exhibited improved tensile strength (35.70 %) and hardness (63.33 %) after the addition of 2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn into A356 alloy, attributed to the strengthening effect of HEA particles. Furthermore, wear resistance is notably enhanced, likely due to the synergistic effects of the HEA’s inherent hardness and the modified microstructure.

Influence of AlCoCrFeNiCuSn HEA reinforcement particles on the plastic flow behaviour of the friction stir processed composite material under constrained confined deformation conditions

In the present investigation, an AlCoCrFeNiCuSn high entropy alloy (HEA) reinforced (with 2.5, 5, 7.5 weight percentage (wt.%)) AA7050-based metal matrix composite has been developed by utilising the friction-stir processing (FSP) technique. Further, the representative volume element (RVE) based finite element analysis (FEA) model and macro-mechanical static indentation FEA model have been developed to analyze the plastic deformation of developed composite material under constrained confined deformation conditions at a load range of 4.90 to 49.03 kN. The microstructural investigation confirms the fair distribution of AlCoCrFeNiCuSn HEA particles in the AA7050 matrix. The micro-mechanical RVE-based FEA model and macro-mechanical static indentation FEA model were successfully validated with experimental and analytical models (ECM and FPM) with less than 5% percentage difference. The yield strength of matrix material was increased with 6.51%, 10.47%, and 15.19% by increasing the AlCoCrFeNiCuSn HEA reinforcement particle with 2.5wt.%, 5wt.%, and 7.5wt.% respectively. Further, the tensile strength of matrix material was increased with 1.88%, 3.93%, and 10.49% by increasing the AlCoCrFeNiCuSn HEA reinforcement particle with 2.5wt.%, 5wt.%, and 7.5wt.% respectively. Additionally, Composition 1 (AA7050/2.5wt.% AlCoCrFeNiCuSn HEA), composition 2 (AA7050/5wt.% AlCoCrFeNiCuSn HEA) and composition 3 (AA7050/7.5wt.% AlCoCrFeNiCuSn HEA) show 7.39%, 11.91% and 22.16% more Meyer’s hardness than matrix material.

Improving wear resistance of Ti6Al6V2Sn alloy by reinforcing AlBeSiTiV high-entropy alloy through microwave sintering

The present study examines the wear performance of microwave-sintered Ti6Al6V2Sn (Ti662) alloy reinforced with 15 wt% AlBeSiTiV High-Entropy Alloy (HEA). The AlBeSiTiV HEA is synthesized by ball milling at 250 rpm for 20 h, resulting in irregular fragments with a mean size of 15 µm and an FCC phase structure. The α-Ti grains decreased with increment of β -Ti grains upon adding HEA reinforcement with the Ti662 alloy. The Ti662/HEA composite exhibited 762 HV microhardness mainly due to refined grains through uniform dissipation in the sintering. The grains sized 0.597 µm on average. The pin-on-disc tribometer is employed to evaluate the wear rate of Ti662/HEA composite under varied process parameters such as applied load, sliding velocity, and sliding distance resulted in enhanced wear resistance through grain refinement, hindering effect, and superior interfacial bonding properties of reinforced HEA particles. Morphological analysis of the worn surfaces reveals wear mechanisms, including delamination, grooves, and the formation of oxide layers. These layers are developed due to the reinforcement of HEA with Ti662 alloy, serving as a protective film over the composite surface against wear.

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.

High entropy alloy particle reinforced 6061 aluminum matrix composites: An investigation of mechanical strength and thermoelectric properties

The relentless pursuit of advanced materials characterized by superior mechanical and thermoelectric properties has spurred significant research into metal matrix composites (MMCs), particularly aluminum matrix composites (AMCs). This study investigates the development of 6061 aluminum alloy composites reinforced with varying concentrations (4–10 wt%) of AlCoCrFeNi high-entropy alloy (HEA) particles via Spark Plasma Sintering (SPS). Key findings underscore the positive impact of HEA reinforcement on the density and hardness of AMCs, while revealing a complex relationship between HEA content and strength. The composite incorporating 6 wt% HEA exhibited optimal properties, characterized by a density of 2.85 g/cm³, Vickers hardness of 85 HV, ultimate tensile strength of 174 MPa, and elongation of 13.7 %. A corresponding peak in thermal conductivity was observed at this composition, while electrical conductivity diminished due to increased phonon scattering.

Microenvironment regulation to synthesize sub-3 nm Pt-based high-entropy alloy nanoparticles enabling compressed lattice to boost electrocatalysis

Platinum (Pt) is inevitably employed to facilitate various electrocatalysis including hydrogen oxidation/evolution and oxygen reduction reactions (HOR/HER/ORR), the foundation for renewable energy conversion and storage. Pt-based high-entropy-alloy (HEA) catalysts have been recently presenting promises to improve intrinsic activity of unit mass Pt. However, their current synthesis methods always produce large particles—some can control small size but have to use complicated recipe and/or highly toxic and expensive chemicals. Alternatively, a facile microenvironment regulation strategy is herein proposed to tune solvent polarity and nanoparticle-support interactions within the precursors for carbon-thermal shock pyrolysis. We found that the decreased solvent polarity and enhanced particle-support affinity can jointly control the nanoparticle size ultimately to ∼2.68 nm with ∼10 wt% Pt loading. The compressed lattice fringe in such HEA particles leads to electron accumulation at Pt atoms and build a moderate charge density rearrangement, showing superior multifunctional HER/HOR/ORR activity to Pt/C in acidic media.

Synergistic enhancement of 7075 aluminum alloy composites via high entropy alloy particle integration: Microstructural and mechanical insights

This study investigates the impact of high-entropy alloy (HEA) particle reinforcement on the microstructure, mechanical properties, and performance of 7075 aluminum matrix composites (AMCs). Utilizing spark plasma sintering (SPS), composites with varying HEA particle concentrations were synthesized to assess their effects comprehensively. The results indicate that increasing HEA content significantly enhances the density and hardness of the composites. Specifically, a 20 wt% HEA reinforcement achieved a high hardness of 61 HRB and a density of 3.21 g/cm³. The compressive strength initially increased with HEA content but then decreased as it ranged from 5 wt% to 20 wt%. Optimal mechanical properties, including a compressive strength of 680 MPa and a fracture elongation of 33 %, were observed at 10 wt% HEA. Wear testing further demonstrated the advantages of HEA reinforcement, with a substantial reduction in wear rate from 9.97 ± 1.1 × 10⁻⁴ to 2.06 ± 0.1 × 10⁻⁴ mm³/N·m at 10 wt% HEA. Additional analyses using energy-dispersive X-ray spectroscopy (EDX) and nanoindentation identified an aluminum-rich transition layer at the HEA-aluminum interface, formed due to aluminum diffusion. This transition layer likely enhances interfacial wettability and bonding, contributing to the improved performance of the composite.

Simultaneous enhancement of strength and ductility of Al matrix composites enabled by submicron-sized high-entropy alloy phases

Our study investigated the reinforcing effect of submicron-sized (100–500 nm) Al0.5CoCrCuFeNi high-entropy alloy particles (HEAps) on the tensile properties of Al matrix composites. The HEAps were refined to the submicron-sized level via a thermal plasma process to maximize reinforcing efficiency by increasing specific surface (i.e., interface) area. The Al/HEA composites were produced by hot rolling of mechanically milled Al/HEA composite powder. The microstructural analysis demonstrated that the HEAps were uniformly dispersed within the Al matrix by forming a sound interface without interdiffusion brittle intermetallic layers or any noticeable voids. Moreover, the addition of 2 vol% HEAps resulted in a simultaneous increase in both yield strength from 355 to 403 MPa and tensile elongation from 1.3 to 3.3%. As a result, the composite experienced a synergistic effect due to the combination of intrinsic strengthening to promote uniform plastic deformation and extrinsic strengthening to mitigate plastic instability and crack propagation.

Optimization of friction stir processing parameters to improve mechanical properties and microstructure of Al5083 aluminum alloy reinforced with AlCoCrFeNiSi high-entropy alloy

Abstract This study explores integrating AlCoCrFeNiSi high-entropy alloy (HEA) particles into the Al5083 aluminum alloy matrix via Friction Stir Processing (FSP) to enhance mechanical characteristics. Microstructural analysis reveals a homogeneous distribution and size reduction of HEA particles, contributing to improved structural strength. X-ray diffraction (XRD) examination confirms the formation of solid solution phases in the HEA particles, validating their role in enhancing material properties. Through the utilization of Design of Experiments (DOE) and Response Surface Methodology (RSM), FSP parameters are systematically optimized, enabling precise predictions of mechanical behavior. Multi-response optimization identifies the optimal combination of FSP parameters, resulting in significant enhancements in Ultimate Tensile Strength (UTS) and Hardness, reaching 314 MPa, 42% elongation, and 75 HV, respectively. Scanning Electron Microscopy (SEM) analysis of tensile test specimens elucidates the impact of varied FSP parameters on microstructural features, emphasizing the importance of optimal mixing for improving interfacial bonding and mechanical properties. This study underscores the effectiveness of integrating HEA particles and optimizing FSP parameters to elevate the mechanical properties of Al5083 aluminum alloy, paving the way for tailored composite materials with enhanced performance for specific applications.

Synergistic-strengthening strategy induce excellent electrical and mechanical properties in Cu/AlCrCuFeNi2.5 composites

A novel high-strength conductive Cu-based composite, utilizing AlCrCuFeNi2.5 (Ni2.5) high-entropy alloy particles as the reinforcing phase, is synthesized through a combination of ball milling and spark plasma sintering processes. The mechanical and electrical properties of the composites are optimized by adjusting the composition. Under the synergistic effect of multiple strengthening mechanisms, the fabricated Cu-20 wt% Ni2.5 composites achieve an exceptional compressive strength of 920 MPa while maintaining an electrical conductivity of 44.3 % IACS (International Standard Copper Standard). The establishment of robust interface bonding between Ni2.5 reinforcement and Cu matrix stands as a pivotal assurance for the holistic performance of composites. Ni2.5 HEA is distinguished by good plasticity and high strength compared with traditional brittle reinforcements. An insight into the differences brought about by the distinctive dual-phase structure in terms of interfacial bonding, crack propagation, and performance is provided. It paves the way for selecting and projecting the composites for electrical contact applications, ushering in a realm of fresh possibilities.

Physio-mechanical and tribological characterisation of sintered aluminium 7068 modified with NiTiFeAlCu high-entropy-alloy for engineering applications

ABSTRACT Metal particles are gaining attention as reinforcement in metal matrix composites owing to their ductility as compared with ceramic particles, which are inherently brittle. High-entropy-alloy (HEA) particles belong to this category based on their high strength, ductility, and thermal stability. Aluminium-7068 is a new aerospace alloy in the 7000 series that possesses higher strength than aluminium-7075, yet very few studies have considered reinforcement with high-entropy alloy particles. For strength improvement, NiTiFeAlCu (HEA) powder was introduced into the aluminium-7068 matrix at 0, 4, 8, and 12 wt. % at 500 °C via vacuum sintering. The microstructure depicted dispersed particles in the matrix with a linear reduction in porosity as the HEA dosage increased. Consequently, there was a linear increase in density and relative density. 4–12 wt.% HEA engendered linear improvements in yield and ultimate tensile strength, elastic modulus, and hardness; meanwhile, elongation was a progressive decline. The outcome of this study shows that HEA particles in AA-7068 resulted in an improvement of the tensile and hardness properties. The particle addition was observed to reduce the composite’s friction coefficient and wear rate. This report revealed that the performance of AA-7068 can be improved up to 12 wt. % NiTiFeAlCu HEA addition.

Effect of sintering temperature on the properties of titanium matrix composites reinforced with Al0·5CoCrFeNi high-entropy alloy particles

In this study, the organization and mechanical properties of the composites were analyzed at different sintering temperatures, and it was found that the local high-temperature phenomenon of discharge plasma sintering led to rapid melting and element diffusion at the junction of the high-entropy alloy particles and the Ti matrix, resulting in the formation of the interfacial layer. The increase in sintering temperature promoted close bonding between particles and element diffusion, caused lattice distortion and new phase formation, and increased the thickness of the interface layer and precipitated phase at the grain boundary. Most of the high-entropy alloy particles were dissolved when the sintering temperature reached 1050 °C. The composites were characterized by a high sintering temperature. The comprehensive mechanical properties of the composites first increased and then decreased when the sintering temperature increased, and they were optimized at 850 °C. The nanoindentation results show that the increase in sintering temperature leads to a decrease in the hardness of the high-entropy alloy particles, an increase in the hardness of the titanium matrix, and a higher hardness of the interfacial layer than that of the high-entropy alloy particles and the titanium matrix.

Unveiling Enhanced Properties via Microstructural Evolution in Stir‐Cast Al6061 Composite Reinforced with AlCrFeNiTi High‐Entropy Alloy Particles

The viability of reinforcing the Al 6061 matrix using AlCrFeNi and AlCrFeNiTi high entropy alloy (HEA) particles is investigated. Body‐centered cubic, A2, and TiC phases are observed in both alloys after 12 h of milling. In situ TiC formation happens during mechanical alloying in AlCrFeNiTi HEA powders. Selected area diffraction patterns are employed in transmission electron investigations to authenticate the presence of distinct phases, affirming their existence within the studied material. Fabricated composites exhibit evenly spaced grains with homogeneous particle dispersion. In comparison to its equivalent, a composite reinforced with AlCrFeNiTi‐C particles exhibits greater grain refinement. Benefiting from dispersion strengthening and grain refinement, both metal matrix composites (MMCs) showcase enhanced attributes. In the case of Al6061/AlCrFeNiTi‐C MMC, a remarkable 25% boost in ultimate tensile strength is achieved, accompanied by a substantial 141.6% improvement in hardness. The findings demonstrate the contribution of HEA particles in improving the characteristics of Al alloys.

High-Entropy Alloy Array via Liquid Metal Nanoreactor.

High-entropy alloy (HEA) nanostructures arranged into well-defined configurations hold great potential for accelerating the development of electronics, photonics, catalysis, and device integration. However, the random nucleation induced by the disparity in physicochemical properties of multiple elements makes it challenging to achieve single-particle synthesis at the patterned preset sites in the high-entropy scenario. Herein, the liquid metal nanoreactor strategy is proposed to realize the construction of HEA arrays. The coalescence of the liquid metal driven by the tendency to decrease surface energy provides a restricted environment for the nucleation and growth to form single HEA particles at the preset locations, which can be regarded as a self-confinement reaction. Liquid metal endowing a low diffusion energy barrier on the substrate and a high diffusivity of the alloy system can dynamically promote the aggregation process. As a result, the HEA array is prepared with elements up to eleven and possesses uniform periodicity, which exhibits excellent holography response in a broad spectrum. This work injects new vitality into the construction of HEA nanopatterns and provides an excellent platform for propelling their fundamental research and applications.