High-entropy Alloy Powders Research Articles

Powder Synthesis and Characterization of Al0.5CoCrFeNi High-Entropy Alloy for Additive Manufacturing Prepared by the Plasma Rotating Electrode Process.

The Al0.5CoCrFeNi high-entropy alloy powder was produced by using a plasma rotating electrode process. The morphology, microstructure, and physical properties of the powder were characterized. The powder exhibited a smooth surface and a narrow particle size distribution with a single peak. The relationships between particle size and secondary dendrite arm space as well as cooling rate were evaluated as follows: λ = 0.0105d + 0.062 and vc = 4.34 × 10-5d-2 + 2.62 × 10-2d-3/2, respectively. The Al0.5CoCrFeNi powder mainly consisted of fcc + bcc phases. As the powder particle size decreased, the microstructure of the powder changed from dendritic to columnar or equiaxed, along with a decrease in the fcc content and an increase in the bcc content. The tap density (4.76 g cm-3), flowability (15.01 s × 50 g-1), oxygen content (<300 ppm), and sphericity (>94%) of the powder indicated suitability for additive manufacturing.

New insights on bonding mechanism of FCC and BCC high entropy alloy microparticles upon supersonic impact using micromechanical adhesion test

Coating buildup in cold spraying (CS) relies on particle bonding upon impact, thus making it a significant area of study. High entropy alloys (HEAs) are a class of materials with superior work-hardening ability and resistance to softening, making their particle impact and bonding particularly important to understand for their cold sprayability. In this study, the splat adhesion strength is measured with a scratch test for FCC CoCrFeMnNi and BCC AlCrFeMnNi HEA microparticles deposited on mirror-polished SS304 substrates. Nanoindentation tests were conducted to estimate the tensile and shear strengths of the HEA powders. The results showed that particle deformation and jetting were dominant in the FCC HEA/SS304 system, while substrate deformation was dominant in the BCC HEA/SS304 system. Focused ion beam cross sections of particles confirmed that the FCC HEA had good bonding and underwent significant deformation and grain refinement at the substrate/particle interface, while the BCC HEA had limited bonding only in the sheared zone of the particles.In spite of the very limited deformation of BCC splats, their average adhesion strength was measured to be 451 ± 141 MPa, which is significantly higher than that of FCC splats, with an average value of 308.7 ± 69.3 MPa. Fracture surface analysis revealed that FCC splats consistently exhibit ductile fracture, regardless of whether it occurs at the particle, substrate, or interface. In contrast, for BCC splats, fracture was ductile when occurring at the interface and substrate sides, while it was cleavage when occurring on the particle side. These findings suggest that the toughness and shear strength of the bonding developed at the interface were higher than those of the particle. It was found that the flattening ratio (FR) of the particles decreases for both FCC and BCC HEA splats with an increase in particle size, resulting in a decrease in adhesion strength. Metallurgical bonding has been identified as the primary factor contributing to the adhesion strength of both FCC and BCC HEA splats. Particle penetration, indicative of mechanical interlocking, appears to have little or no effect on adhesion strength. However, it does positively influence the increase in adhesion energy of the splats.

Phase transformation and strengthening of the gas-atomized FeCoCrNiMo0.5Al1.3 high-entropy alloy powder during annealing

Phase evolution and strengthening of the FeNiCoCrMo0.5Al1.3 powder alloy produced via inert gas atomization and annealed in the temperature interval of 300–800 °C have been studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and microhardness testing. It was found that annealing at 300–600 °C leads to an increase of the element segregations between the several solid solutions with a rise of the lattice misfit (ε) to 1.5 % and microhardness growth to 1070 HV. It was assumed that elastic stress caused by the element partitioning is the main strengthening mechanism: microhardness rises linearly with misfit rise with dHV/dε = 43400 MPa. Sigma arises after the maximum elastic deformation (in 1.5 %) was reached. Formation of the dispersed coherent sigma phase in the annealing interval 600–800 °C results in the microhardness rise. Oxidation that began at 800 °C in 27 h is accompanied with FCC formation due to a depletion of the B2 in Al caused by Al2O3 formation. Estimation of the activation energy of the initial stage of the solid solution decomposition gives a very low value in 0.65eV, apparently caused by the high concentration of quenched vacancies. The activation energy of sigma formation approximately coincides with the activation energy of self-diffusion in BCC metals (about 2.60 eV).

Microstructure and mechanical properties of CoCrFeNiTa high entropy alloy prepared by mechanical alloying and spark plasma sintering

The equiatomic CoCrFeNiTa high-entropy alloy (HEA) was prepared by mechanical alloying and spark plasma sintered at different temperatures in this work. The microstructural evolution of alloy powder and microstructure and mechanical properties of the sintered HEA were investigated. The results show that the particle size of HEA powder is decreased gradually with the increase of milling time and then tends to be unchanged basically. The composition of the HEA powder becomes uniform, and metastable face-centered cubic (FCC) phase and Laves phase with Co2Ta type are obtained eventually. The HEA sintered at 1100 °C exhibits a near-full density (99.15%). Supersaturated FCC and Laves phases with a grain size of 1.32 μm and 1.26 μm are formed in the HEA blocks, and many Ta2[Co, Cr, Fe] precipitates with a size of about 23 nm were observed in the FCC matrix. Mechanical properties were measured using Vickers hardness and uniaxial compression testing techniques. The HEA sintered at 1100 °C shows an ultra-high hardness of 9.37 GPa and compressive strength of 2177 MPa respectively. This is mainly ascribed to the combined effect of the grain refinement strengthening, solid solution strengthening, second phase strengthening including Laves phase and nano-sized precipitates. It provides a new way to prepare high strength and high hardness materials.

Preparation and performance of high entropy alloy reinforced Cu-based bond diamond tool

The research on the influence of hot-press sintering on the properties of AlFeCrCoNi high-entropy alloy powders reinforced copper (HEA/Cu) alloys and the application of HEA/Cu alloys in diamond tools is still limited. Therefore, a new metal bond based on hot-press sintered HEA/Cu alloy for the diamond tool is proposed in this paper. The effect of adding HEA powder on the microstructure, mechanical, and tribological properties of the HEA/Cu alloy is investigated. A metal bond diamond tool based on the HEA/Cu alloy is prepared by hot-press sintering, and its grinding performance on alumina ceramic is examined. The results show that mutual element diffusion occurs between the HEA and Cu matrix during sintering, densifying the HEA/Cu alloys. The Cu alloy presents a higher hardness, yield strength, and wear resistance with a higher content of HEA powder. The hardness, yield strength, and wear resistance of Cu alloy are increased by 53.4%, 332%, and 200%, respectively, with the addition of 20 wt% HEA powders. The HEA/Cu bond diamond tool presents grinding forces and surface roughness equal to those of a commercial Cu-based alloy bond diamond tool.

Laser Powder Bed Fusion Printing of CoCrFeMnNi High Entropy Alloy: Processing, Microstructure, and Mechanical Properties

Equiatomic CoCrFeMnNi high entropy alloy (HEA) powder was processed by laser powder bed fusion (LPBF) additive manufacturing (AM). The properties of the spherical pre-alloyed CoCrFeMnNi powder were characterized and its processability using LPBF AM was systematically investigated through the volumetric energy density (VED) based on the surface roughness, defects (micro-cracks and porosity) and densification. After optimization, LPBF processing at a VED of 104 J/mm3 achieved highly dense and crack-free vertical and horizontal test specimens with a porosity fraction lower than 0.01% and micro-pores having a mean size of, respectively, 25.9 μm and 13.4 μm, as determined from X-ray micro-computed tomography (μCT) inspection. Scanning electron microscope (SEM) analysis of the as-built (AB) CoCrFeMnNi processed at a VED of 104 J/mm3 showed a heterogeneous solidification microstructure, consisting of columnar grains with a cellular subgrain structure, and electron backscattered diffraction (EBSD) revealed a crystallographic texture mainly along the < 100 > direction. Post treatment with hot isostatic pressing (HIP) was effective in closing the remnant micro-pores in the bulk volume of the AB CoCrFeMnNi. Also, the cellular sub-grain structure in the AB CoCrFeMnNi completely disappeared after HIP and the resulting microstructure consisted of recrystallized equiaxed grains with annealing twins. The room temperature tensile response was anisotropic for AB CoCrFeMnNi with horizontally built specimens exhibiting higher strength and fracture strains (global and local) compared to vertically built ones; HIP reduced the anisotropy in the tensile properties and led to similar tensile strength with elongation values that were ~ 50% higher than in the AB condition. The HIPed CoCrFeMnNi also displayed higher Charpy impact toughness and absorbed energy at both room and liquid nitrogen temperatures compared to the AB material. Examination of the fracture surfaces after tensile and Charpy impact testing revealed ductile features with characteristic dimpled appearance and pointed to the important role of the remnant micro-pores on failure in the AB CoCrFeMnNi. Tribological assessments pointed to the superior low-stress abrasion resistance of AB and HIPed CoCrFeMnNi compared to 316L stainless steel (SS), which was included in this study to reinforce the analysis. SEM observations revealed that scratching and micro-fracture are the dominant wear mechanisms for the CoCrFeMnNi HEA, whereas ploughing and cutting parallel to the abrasive flow direction are the dominant mechanisms for 316L SS. To the authors’ knowledge, this study is the first to evaluate and report the low-stress abrasion resistance of any high entropy alloy. To understand the corrosion behavior, polarization curves of AB and HIPed CoCrFeMnNi were measured in 3.5 wt% NaCl and 1N H2SO4 solutions, and the results were compared to those of 316L SS. The findings indicate that AB and HIPed CoCrFeMnNi outperform 316L SS in a chloride-containing environment, but not in an acid-containing environment. Additionally, observations of hydrogen permeability revealed that AB CoCrFeMnNi permeates a lower volume of hydrogen atoms (by ~ 5 times) compared to 316L SS, despite its higher (by nearly 3 times) diffusion coefficient. Electrochemical hydrogen permeation data showed that the concentration of atomic hydrogen in the sub-surface of AB and HIPed CoCrFeMnNi was, respectively, about 32 and 26 times lower than in 316L SS. This study provides important material–structure–property data and indicates a promising outlook for LPBF of the CoCrFeMnNi HEA with high-performance.

Oxidation Behavior of FeNiCoCrMo0.5Al1.3 High-Entropy Alloy Powder.

One of the most promising applications of FeNiCoCrMoAl-based high-entropy alloy is the fabrication of protective coatings. In this work, gas-atomized powder of FeNiCoCrMo0.5Al1.3 composition was deposited via high-velocity oxygen fuel spraying. It was shown that in-flight oxidation of the powder influences the coating's phase composition and properties. Powder oxidation and phase transformations were studied under HVOF deposition, and during continuous heating and prolonged isothermal annealing at 800 °C. Optical and scanning electron microscopy observation, energy dispersive X-ray analysis, X-ray diffraction analysis, thermogravimetric analysis, differential thermal analysis, and microhardness tests were used for study. In a gas-atomized state, the powder consisted of BCC supersaturated solid solution. The high rate of heating and cooling and high oxygen concentration during spraying led to oxidation development prior to decomposition of the supersaturated solid solution. Depleted Al layers of BCC transferred to the FCC phase. An increase in the spraying distance resulted in an increase in α-Al2O3 content; however, higher oxide content does not result in a higher microhardness. In contrast, under annealing, the supersaturated BCC solid solution decomposition occurs earlier than pronounced oxidation, which leads to considerable strengthening to 910 HV.

Synthesis of CrMnFeCoNi High Entropy Alloys Powders by Powder Metallurgy and Composite with Al

Synthesis of CrMnFeCoNi High Entropy Alloys Powders by Powder Metallurgy and Composite with Al

Effect of Reduced Graphene Oxide on Microwave Absorbing Properties of Al1.5Co4Fe2Cr High-Entropy Alloys.

The microwave absorption performance of high-entropy alloys (HEAs) can be improved by reducing the reflection coefficient of electromagnetic waves and broadening the absorption frequency band. The present work prepared flaky irregular-shaped Al1.5Co4Fe2Cr and Al1.5Co4Fe2Cr@rGO alloy powders by mechanical alloying (MA) at different rotational speeds. It was found that the addition of trace amounts of reduced graphene oxide (rGO) had a favorable effect on the impedance matching, reflection loss (RL), and effective absorbing bandwidth (EAB) of the Al1.5Co4Fe2Cr@rGO HEA composite powders. The EAB of the alloy powders prepared at 300 rpm increased from 2.58 GHz to 4.62 GHz with the additive, and the RL increased by 2.56 dB. The results showed that the presence of rGO modified the complex dielectric constant of HEA powders, thereby enhancing their dielectric loss capability. Additionally, the presence of lamellar rGO intensified the interfacial reflections within the absorber, facilitating the dissipation of electromagnetic waves. The effect of the ball milling speed on the defect concentration of the alloy powders also affected its wave absorption performance. The samples prepared at 350 rpm had the best wave absorption performance, with an RL of -16.23 and -17.28 dB for a thickness of 1.6 mm and EAB of 5.77 GHz and 5.43 GHz, respectively.

High-entropy borides with frame structure: Efficient electrocatalysts for oxygen evolution reaction

Innovative methods for producing catalytic nanomaterials are crucial for advancing environmental conversion and storage technologies. This study introduces a novel approach to fabricate a high-entropy boride alloy with a frame structure, FeCoNiMgB/NF, using in situ growth of high-entropy alloy powder on nickel foam (NF). The resulting frame-structured FeCoNiMgB/NF high-entropy boride alloy exhibits superior electrocatalytic performance for the oxygen evolution reaction (OER) compared to pure FeCoNiMgB powder and other counterparts. It demonstrates a low overpotential of 183 mV at a current density of 10 mA cm−2, a Tafel slope of 34 mV dec−1 in 1 M KOH, and excellent stability over 72 h without significant decay.The outstanding catalytic performance of the frame-structured FeCoNiMgB/NF high-entropy alloy can be attributed to the synergistic effects of FeCoNiMgB–NF, a larger specific surface area, and excellent frame-structure conductivity. The alloy's long-term stability is a result of the gradual formation of the FeCoNiMgOOH lath structure array during the reaction process, facilitating low adsorption and charge transfer energies as per theoretical calculations. This study presents a new method for constructing advanced frame-structured high-entropy boride alloys, promising advancements in energy conversion and storage technologies.

A study on microstructural, mechanical properties and optimization of wear behavior of friction stir processed AlCrCoFeNi High Entropy Alloy reinforced SS410 using response surface methodology

The equimolar High Entropy Alloy (HEA) is incorporated on the surface of SS410 steel to enhance the mechanical properties for the current industrial scenario. The objective of the present work is to make a first attempt at surface modification of SS410 steel with gas atomization synthesized AlCrCoFeNi HEA powder through Friction Stir Processing (FSP). The microhardness and ultimate tensile strength of the FSP-HEA sample are increased by 41.3 % and 39.1 % respectively due to the high degree of refined grains with 2.84 μm and evenly distributed HEA particles. The wear rate of FSP-HEA samples is optimized by response surface methodology with process parameters including applied load, sliding distance, and sliding velocity. The most influential factor and regression model are derived from experimental results that predict the wear rate by the analysis of variance technique. The worn surface of FSP-HEA samples is evaluated by morphological analysis with corresponding induced wear mechanisms. The minimum wear rate is achieved by optimum process parameters along with higher hardness through particle-stimulated nucleation mechanism, Hall-Petch relation, and dynamic recrystallization. The grain refinement, barrier effect, and grain growth hindrance of HEA particles lead to enhancement in the strength of processed HEA samples.

High entropy alloy cladding on mild steel substrate using microwave energy at 2.45 GHz: An insight from multi-physics simulation study to experimental investigations

Microwave hybrid heating (MHH) has emerged as a novel technology for cladding high-entropy alloy (HEA) powders on metallic substrates. The existence of a multi-material system (Al, Co, Cr, Ni, and Ti powder) in HEA provides difficulties in microwave cladding. These problems are addressed in the current study by employing silicon carbide as a susceptor material for MHH to microwave-clad AlCoCrNiTi HEA on a mild steel substrate. A multi-physics model of the microwave cladding setup was constructed to investigate the cladding properties. The model was verified using experimental data, and simulation was used to examine the electric field, resistive losses, energy distributions, and temperature-time profile. The simulation results indicated that the electric field intensity, resistive losses, and energy distribution were at their maximum near the susceptor and the cladded surface. As a result, the HEA-cladded surface reached a temperature of 1030 °C at the central plane. This is comparable to the experimental temperature of 1041 °C in 41 min, which shows an error of <10 %. From the microstructural investigation, the HEA powder exhibited a flaky microstructure and a uniform distribution of all the constituents, resulting in a solid metallurgical link between the HEA powder and substrate. The surface hardness of mild steel components was enhanced intensely by three times with the inclusion of AlCoCrNiTi HEA cladding.

Addressing challenges in high-temperature oxidation of ultra-supercritical boiler tubes via FeCoNiCrMo high-entropy alloy coatings

The engineering realm confronts formidable challenges in combating the persistent issue of high-temperature oxidation in ultra-supercritical coal-fired boiler tubes. This study is dedicated to tackling these challenges by employing high-velocity oxy-fuel spraying (HVOF) and high-frequency induction remelting techniques. Our primary objective is to establish a metallurgical bond between self-fusing FeCoNiCrMo high-entropy alloy (HEA) powder and the conventional 15CrMo boiler steel tube surfaces, all within ambient atmospheric conditions. Our investigation reveals two distinct stages of oxidation for the HEA coating when exposed to a 900 °C air environment. Initially, there is a rapid oxidation stage driven by interfacial reactions, followed by a steady-state slow oxidation stage influenced by ion diffusion. The presence of a dense Cr2O3 layer plays a pivotal role in reducing the oxidation rate significantly, thereby imparting exceptional high-temperature oxidation resistance to the FeCoNiCrMo HEA coating. Notably, during the steady-state stage, the oxidation rate is two orders of magnitude lower than observed in Ni-based superalloys. Minimal phase transformations or transitional layers at the interface underscore superb interface bonding at 900 °C. These findings provide a promising avenue for the cost-effective fabrication of highly oxidation-resistant ultra-supercritical boiler tubes. This advancement contributes significantly to the progress of engineering applications.

Effect of Al content on the microstructure and mechanical alloying behavior of AlCoCuMnNi and Al0.25CoCuMnNi high entropy powders

The concept of high entropy alloys (HEAs) is an emerging subject in materials science and engineering. The presence of at least four elements in equiatomic or near equiatomic composition in HEAs has led to superior properties and vast unexplored alloying space. In this study, we investigated two new HEA powders, AlCoCuMnNi and Al0.25CoCuMnNi, by subjecting mechanically milled (MM) powders to a series of analyses over a 60 h ball milling process. It was found that alloying starts after 20 h of MM and after 45 h, full elemental integration into the host lattice was detected. Meanwhile, further milling to 60 h can cause powder contamination. The High-Resolution Transmission Electron Microscopy (HRTEM) results validated the XRD findings and provided further insights into the substantial influence of Al content on the microstructure and the extent of amorphization within the milled powders. Differential Thermal Analysis (DTA) analysis on the MM powders showed one exothermic peak for AlCoCuMnNi and one for Al0.25CoCuMnNi at high temperatures, which may suggest the formation of the BCC or second FCC phases for these alloys. The results confirmed the significant influence of the increased Al content on increasing both the lattice constant and lattice strain while decreasing thermal stability of the investigated MM powders. The present results provided insights needed for consolidation of such HEA powders.

Numerical and experimental investigation of close-coupled twin-nozzle gas atomization towards fine high-entropy alloy powder production

The close-coupled nozzle is key to controlling the particle diameter and powder defects such as satellite particles during the production of metal powders via vacuum induction melting gas atomization (VIGA). However, new nozzle structures with greatly improved fine particle yields and morphologies are needed. Also, there is a limited understanding of how gas atomization refines particles and forms satellite particles. Therefore, we developed a novel close-coupled twin-nozzle and revealed the effect of different primary and secondary pressures on the gas flow field, melt atomization, and particle characteristics (particle diameter, sphericity, and satellite particles). This approach involved both numerical simulations and experiments during the production of an AlCoCrFeNi2.1 alloy. The results showed that the particle diameter and distribution width decreased under various combinations of process parameters. This was because of the combined actions of the gas recirculation zone in the air, where the vortex was close to the bottom wall of the delivery tube and a gas jet. The yield of fine particles in the ≤ 45 µm range produced by the twin-nozzle increased to 79.25% from 55.55% upon increasing the secondary pressure from 1.0 MPa to 2.0 MPa, achieving up to a 34.12% higher fine particle yield compared with the conventional single-nozzle. In addition, as the secondary pressure of the twin-nozzle was increased, the number of satellite particles decreased, which also affected the proportion of L12/B2 phase within the powder, causing the Vickers microhardness to decrease and then increase as the particle diameter increased.

The microstructural evolution and enhanced mechanical properties of in-situ Ti(C, N)-reinforced CoCrFeNiTi high-entropy alloy composites fabricated via mechanical alloying and spark plasma sintering

A new metal-matrix composite, fine Ti(C, N) particles reinforced CoCrFeNiTi high-entropy alloy (HEA), were successfully fabricated via mechanical alloying and spark plasma sintering process. Graphite carbon nitrides (g-C3N4) particles and equiatomic CoCrFeNiTi HEA powders were used as the original materials. The microstructural investigations have been carried out with scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM), and the results reveal that the increase in strength can be ascribed to grain refinement and dislocation strengthening, particularly the fine Ti(C, N) particle strengthening. The fracture modes of composites are mainly combination of brittle fracture with ductile fracture. An interesting microstructural feature is that the fine HEA grains are distributed within Ti(C, N) particles forming a core-shell structure, which further improves the fracture toughness of the composites. The final composite (Ti(C, N)/CoCrFeNiTi HEA) shows exhibits the best combination of compressive strength and fracture toughness, which are 2965 MP and 12.4 MPa m1/2, respectively. The present study not only expands the application field of g-C3N4 but also provides a new idea for the preparation of composites reinforced with Ti(C, N) particles.

Preparation of graphene film reinforced CoCrFeNiMn high-entropy alloy matrix composites with strength-plasticity synergy via flake powder metallurgy method

Inspired by the design principle of pearl structure, a bottom-up flake powder self-assembly arrangement strategy, flake powder metallurgy, is used to prepare graphene films (GFs) reinforced CoCrFeNiMn high-entropy alloy (HEA) matrix composites with a pearl laminated structure. Flaky HEA powder was prepared by ball milling method and homogeneously mixed with Ni plated GFs. Vacuum hot-press sintering (VHPS) technique was carried out to solidify the mixed powders to obtain composites with uniform distribution of GFs(Ni) and flaky HEA. The results show that the bottom-up preparation strategy can effectively fabricate bionic laminated HEA matrix composites, and the composites have a distinct pearly laminated structure. The tensile strength of the composites with 5 vol% GFs(Ni) content reached 834.04 MPa, and the elongation reached 26.58 %. The compressive strength in parallel and perpendicular laminar directions reached 2069.66 MPa and 2418.45 MPa at 50 % strain, respectively. The laminated GFs(Ni)/HEA matrix composites possessed excellent strength and maintained good plasticity. In this study, the strengthening and toughening mechanism of the laminated GFs(Ni)/HEA matrix composites is discussed in detail, and the results show that the laminated structure and GFs(Ni) are favorable for the hardening and strengthening of the HEA matrix.

CoCrFeNiSi high entropy alloy: Synthesis, structural and radiation shielding properties

High entropy alloys (HEAs) have emerged as a distinct class of alloys with unique design strategies, different from traditional alloys. These alloys hold great promise for diverse applications, and the investigation of their nuclear radiation shielding properties has become an important and emerging area of research. In this experimental study, an equimolar CoCrFeNiSi HEA was prepared using the ball milling method. The focus was on characterizing the crystalline structure, morphological features, and radiation shielding properties of the synthesized HEA. X-ray diffraction analysis revealed that the HEA exhibited a face-centered cubic (FCC) phase structure. The crystallite size was significantly reduced from 23.63 nm to 3.22 nm, indicating the refinement of the microstructure. The homogeneity of the alloy was confirmed through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), which showed that the five elements were uniformly distributed within the powder alloy. To evaluate the radiation shielding properties, linear attenuation coefficients (LAC) of the CoCrFeNiSi HEA powder were measured using a 662 keV gamma source and a NaI(Tl) detector system (ORTEC® 905–4). The experimental LAC values were determined to be 0.2140 ± 0.01 cm⁻1. Theoretical calculations using MCNP6.2 and XCOM code were also performed and showed good agreement with the experimental results. Comparing the CoCrFeNiSi HEA with common shield materials such as thin films, glass systems, and some composites, it was found that the HEA outperformed them in terms of radiation shielding effectiveness. This demonstrates the potential of the CoCrFeNiSi HEA as an advanced alternative to conventional shielding materials, with potential applications in various fields.

Microstructure and Physical Properties of Nonmagnesium and Magnesium-Based High-Entropy Alloys: A Comparison Study

Abstract In this investigation, (Ti-Mo-Zr)60Co20Cr20, (Ti-Mo-Zr)60Al30Si10 (non-magnesium-based), and (Ti-Mo-Zr)60Cu10Mg30 (magnesium-based) high-entropy alloy (HEA) samples are prepared via mechanical milling and then by spark plasma sintering technique. The microstructure morphology is examined using x-ray diffraction and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The microstructure reveals that there would be a strong correlation between phase structure and sustainability for localized corrosion behavior. The lowest crystallite size of the magnesium-based HEA powder mixture suggests the highest corrosion resistance because of the solid-solution face-centered cubic and body-centered cubic phases for 20 h of milling. The correlation between the microstructural morphology and functional properties such as hardness, corrosion resistance, and potentiodynamic parameters are compared for both magnesium-based and non-magnesium-based HEAs and analyzed to elucidate their suitability for lightweight vehicle applications.

Adding high entropy alloys to improve microstructure and properties of laser cladding Fe-based amorphous coatings

In this study, the A-H coatings (abbreviation for Fe-based amorphous and high-entropy alloy), which is consist of Fe-based amorphous powders and adding trace high-entropy alloy (HEA) powders, were prepared via laser cladding technique. The microstructure and properties of the A-H coatings and the Fe-based amorphous coatings were investigated in detail using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). It is found that the number of pores, cracks and dendrites of the A-H coatings is reduced due to the formation of Fe3Ni embedded in amorphous phase compared with Fe-based amorphous coatings. The average microhardness of the A-H coatings is about 1519.2±35.7 HV0.2, which is improved by 38.7%. The wear rate of the A-H coatings is found to decrease by 45.8%. Furthermore, A-H coatings exhibited exceptional corrosion resistance, with a polarization resistance that increased by 31.7%. The addition of HEA is a potential strategy to improve microstructure and properties of Fe-based amorphous coatings.