Multicomponent Nanoparticles Research Articles

Unlocking the potential of multicomponent mesoporous bioactive glass nanoparticles: An approach to enhanced ion therapy

This work presents the synthesis and characterization of a multicomponent mesoporous bioactive glass (MMBG) derived from the composition of 58S glass modified with copper, zinc, and boron. Morphological data revealed the presence of spherical particles with an average size of 616 nm and a specific surface area of 295 m2·g−1. X-ray diffractogram analysis confirmed the lack of long-range order in the MMBG, indicating the presence of a disordered vitreous structure characteristic of glass. The structural scenario of the bioactive glass MMBG reveals a characteristic configuration of borosilicate glasses, where the [BO4] polyhedra, along with SiO4 tetrahedra, constitute the backbone of the glassy matrix. Concerning zinc and copper ions, they function similarly to calcium in compensating for the remaining negative charges within the borosilicate network, behaving as typical network-modifying ions. The presence of these heavy ions, coupled with the formation of the borosilicate network in MMBG, led to a 20 % increase in density compared to 58S glass. Additionally, alterations in the chemical composition and structure of MMBG resulted in a reduction in molar volume compared to 58S, indicating a decrease in the volume occupied by one mole of oxygen in the glass matrix, thereby increasing the oxygen packing density. The pH studies reveal that changes in the chemical composition of MMBG did not compromise its chemical reactivity in aqueous environments. The capability of MMBG glass to act as a bioactive agent for ion therapy is evidenced by its ability to deliver Zn and Cu ions, as substantiated by the gradual disappearance of absorption in wavenumber range of 690–470 cm−1, attributed to the vibration of Zn-O and Cu-O bonds. Preliminary in vitro assay for bioactivity in SBF revealed that the formation of apatite layer on the surface of MMBG glass was notably thicker and denser compared to 58S glass. This result highlights the superior bioactive response of the MMBG bioactive glass, indicating its potential as an exceptionally favorable material for various biomedical applications.

Solvent Isotherms and Structural Transitions in Nanoparticle Superlattice Assembly.

We introduce a Molecular Theory for Compressible Fluids (MOLT-CF) that enables us to compute free energies and other thermodynamic functions for nanoparticle superlattices with any solvent content, including the dry limit. Quantitative agreement is observed between MOLT-CF and united-atom molecular dynamics simulations performed to assess the reliability and precision of the theory. Among other predictions, MOLT-CF shows that the amount of solvent within the superlattice decreases approximately linearly with its vapor pressure and that in the late stages of drying, solvent-filled voids form at lattice interstitials. Applied to single-component superlattices, MOLT-CF predicts fcc-to-bcc Bain transitions for decreasing vapor pressure and for increasing ligand length, both in agreement with experimental results. We explore the stability of other single-component phases and show that the C14 Frank-Kasper phase, which has been reported in experiments, is not a global free-energy minimum. Implications for precise assembly and prediction of multicomponent nanoparticle systems are discussed.

Atomistic study of CoCrCuFeNi high entropy alloy nanoparticles: Role of chemical complexity

High entropy alloy nanoparticles are envisaged as one of the most interesting materials compared to monoatomic materials due to their modulated properties in terms of their convenient surface-to-volume ratio. However, studies are still missing to unveil how composition or nanoparticle size can influence nanoparticle morphology. Based on molecular dynamics simulations, we perform a structural characterization as a function of nanoparticle size and the chemical composition of high entropy alloy nanoparticles subject to multiple annealing cycles. After the multiple thermal loads, we observe a substantial migration of copper atoms towards the np surface, consistent with the experimental results of Cu-based high entropy alloys. The resulting high entropy alloy nanoparticle behaves as a core–shell nanostructure with a rich fcc phase on the surface (50% of Cu) and 5% fcc phase in the nanoparticle core. Inspecting the nanoparticle surface, it is observed that high entropy alloy nanoparticles have a lack of surface facets, leading to a more spherical shape, quite different from mono-metallic nanoparticles with a high number of facets. Performing an average atoms simulation, it showed that nanoparticles are prone to form 111 surface facets independent of the nanoparticle size, suggesting that for high entropy alloy nanoparticles, the chemical complexity avoids the formation of surface facets. The latter can be explained in terms of the lattice distortion inducing tensile/compressive stress that drives the surface reconstruction. All in all our results match extremely well with experimental evidence of FeNiCrCoCu nanocrystalline materials, explaining the Cu segregation in terms of surface energy and mixing enthalpy criteria. We believe that our results provide a detailed characterization of high entropy nanoparticles focusing on how chemical complexity induces morphological changes compared to mono-crystalline nanoparticles. Besides, our findings are valuable for experimental works aimed at designing the shape and composition of multicomponent nanoparticles.

An Unprecedented Metal Distribution in Silica Nanoparticles Determined by Single-Particle Inductively Coupled Plasma Mass Spectrometry.

Metal-containing nanoparticles are now common in applications ranging from catalysts to biomarkers. However, little research has focused on per-particle metal content in multicomponent nanoparticles. In this work, we used single-particle inductively coupled plasma mass spectrometry (ICP-MS) to determine the per-particle metal content of silica nanoparticles doped with tris(2,2'-bipyridyl)ruthenium(II). Monodispersed silica nanoparticles with varied Ru doping levels were prepared using a water-in-oil microemulsion method. These nanoparticles were characterized using common bulk-sample methods such as absorbance spectroscopy and conventional ICP-MS, and also with single-particle ICP-MS. The results showed that averaged concentrations of metal dopant measured per-particle by single-particle ICP-MS were consistent with the bulk-sample methods over a wide range of dopant levels. However, the per-particle amount of metal varied greatly and did not adhere to the usual Gaussian distribution encountered with one-component nanoparticles, such as gold or silver. Instead, the amount of metal dopant per silica particle showed an unexpected geometric distribution regardless of the prepared doping levels. The results indicate that an unusual metal dispersal mechanism is taking place during the microemulsion synthesis, and they challenge a common assumption that doped silica nanoparticles have the same metal content as the average measured by bulk-sample methods.

Synthesis and Unique Behaviors of High-Purity HEA Nanoparticles Using Femtosecond Laser Ablation.

High-entropy alloys (HEAs) are a class of metal alloys consisting of four or more molar equal or near-equal elements. HEA nanomaterials have garnered significant interest due to their wide range of applications, such as electrocatalysis, welding, and brazing. Their unique multi-principle high-entropy effect allows for the tailoring of the alloy composition to facilitate specific electrochemical reactions. This study focuses on the synthesis of high-purity HEA nanoparticles using the method of femtosecond laser ablation synthesis in liquid. The use of ultrashort energy pulses in femtosecond lasers enables uniform ablation of materials at significantly lower power levels compared to longer pulse or continuous pulse lasers. We investigate how various femtosecond laser parameters affect the morphology, phase, and other characteristics of the synthesized nanoparticles. An innovative aspect of our solution is its ability to rapidly generate multi-component nanoparticles with a high fidelity as the input multi-component target material at a significant yielding rate. Our research thus focuses on a novel synthesis of high-entropy alloying CuCoMn1.75NiFe0.25 nanoparticles. We explore the characterization and unique properties of the nanoparticles and consider their electrocatalytic applications, including high power density aluminum air batteries, as well as their efficacy in the oxygen reduction reaction (ORR). Additionally, we report a unique nanowire fabrication phenomenon achieved through nanojoining. The findings from this study shed light on the potential of femtosecond laser ablation synthesis in liquid (FLASiL) as a promising technique for producing high-purity HEA nanoparticles.

Tailoring Hot-Carrier Distributions of Plasmonic Nanostructures through Surface Alloying.

Alloyed metal nanoparticles are a promising platform for plasmonically enabled hot-carrier generation, which can be used to drive photochemical reactions. Although the non-plasmonic component in these systems has been investigated for its potential to enhance catalytic activity, its capacity to affect the photochemical process favorably has been underexplored by comparison. Here, we study the impact of surface alloy species and concentration on hot-carrier generation in Ag nanoparticles. By first-principles simulations, we photoexcite the localized surface plasmon, allow it to dephase, and calculate spatially and energetically resolved hot-carrier distributions. We show that the presence of non-noble species in the topmost surface layer drastically enhances hot-hole generation at the surface at the expense of hot-hole generation in the bulk, due to the additional d-type states that are introduced to the surface. The energy of the generated holes can be tuned by choice of the alloyant, with systematic trends across the d-band block. Already low surface alloy concentrations have a large impact, with a saturation of the enhancement effect typically close to 75% of a monolayer. Hot-electron generation at the surface is hindered slightly by alloying, but here a judicious choice of the alloy composition allows one to strike a balance between hot electrons and holes. Our work underscores the promise of utilizing multicomponent nanoparticles to achieve enhanced control over plasmonic catalysis and provides guidelines for how hot-carrier distributions can be tailored by designing the electronic structure of the surface through alloying.

Employing the Microemulsion Synthesis Technique to Investigate the Structural and Magnetic Properties of Multicomponent Ferrite Nanoparticles

AbstractCoFe2O4, ZnFe2O4, NiFe2O4, Co0.5Ni0.5Fe2O4, Ni0.5Zn0.5Fe2O4, and Co0.5Zn0.5Fe2O4 are among the multicomponent ferrite nanoparticles that are created using the reverse microemulsion technique and a mixed surfactant. These nanoparticles are thoroughly characterized using techniques such as vibrating sample magnetometer (VSM), energy dispersive X‐ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray diffraction (XRD). All the nanoparticles display a cubic spinel crystal structure, according to the X‐ray investigation. As the concentration of zinc increases, there is a noticeable rise in the lattice constant because the size of Zn+2 is more than Co+2. This study also investigates the relationship between the magnetic characteristics of nanocrystals and their matching size, composition, and features.

The microstructure and mechanical properties of multicomponent MgAlCe-LDO nanoparticle reinforced Mg matrix composite

The strength-ductility trade-off has long challenged particle-reinforced metal matrix composites (MMCs). This paper presents a multi-component layered double oxide (LDO) interfacial structured Mg matrix composite with high strength and plasticity by introduction of Ce. The LDO contains multi-component irregular nanoparticles (MgO, CeO2, Al3Ce and MgAl2O4) bonding the matrix and MgAlCe. Especially, Ce atoms participates in the formation of Al3Ce and are absorbed on the growing tip of β-Mg17Al12, which further refine the matrix grand and β-Mg17Al12 grain significantly by inhibiting grain boundary migration. During loading, the multi-component LDO can significantly improve load-transfer enhancement and contribute to dislocation-bypass across the LDO/matrix interface. This unique multi-component interfacial structure and fine grains of MgAlCe-LDO nanoparticle reinforced Mg matrix composite contributes to the high ductility and strength (UCS:407 MPa, YS:232 MPa) by increasing 50.2%, and 139.2% without sacrificing ductility (strain 20.6%).

Coassembled Multicomponent Protein Nanoparticles Elicit Enhanced Antibacterial Activity.

The waning pipeline of the useful antibacterial arsenal has necessitated the urgent development of more effective antibacterial strategies with distinct mechanisms to rival the continuing emergence of resistant pathogens, particularly Gram-negative bacteria, due to their explicit drug-impermeable, two-membrane-sandwiched cell wall envelope. Herein, we have developed multicomponent coassembled nanoparticles with strong bactericidal activity and simultaneous bacterial cell envelope targeting using a peptide coassembly strategy. Compared to the single-component self-assembled nanoparticle counterparts or cocktail mixtures of these at a similar concentration, coassembled multicomponent nanoparticles showed higher bacterial killing efficiency against Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli by several orders of magnitude (about 100-1,000,000-fold increase). Comprehensive confocal and electron microscopy suggest that the superior antibacterial activity of the coassembled nanoparticles proceeds via multiple complementary mechanisms of action, including membrane destabilization, disruption, and cell wall hydrolysis, actions that were not observed with the single nanoparticle counterparts. To understand the fundamental working mechanisms behind the improved performance of coassembled nanoparticles, we utilized a "dilution effect" system where the antibacterial components are intermolecularly mixed and coassembled with a non-antibacterial protein in the nanoparticles. We suggest that coassembled nanoparticles mediate enhanced bacterial killing activity by attributes such as optimized local concentration, high avidity, cooperativity, and synergy. The nanoparticles showed no cytotoxic or hemolytic activity against tested eukaryotic cells and erythrocytes. Collectively, these findings reveal potential strategies for disrupting the impermeable barrier that Gram-negative pathogens leverage to restrict antibacterial access and may serve as a platform technology for potential nano-antibacterial design to strengthen the declining antibiotic arsenal.

Creation of polystyrene nanoparticle patterns for structural color application

The ability to regulate the spatial distribution of nanoparticles to generate patterns/arrays makes them promising applications in various fields. Here, a versatile and potential method, based on the polymer brushes patterned surface with hydrophilic-hydrophobic contrast characteristic, was developed to create the nanoparticle patterns with complicated architectures and controllable structural colors on the silicon/glass substrate. Employing DMD-mediated Photo-ATRP process, the selective growth of hydrophilic poly (ethylene glycol) methyl acrylate (PEGMA) brushes on the surface functionalized with hydrophobic initiators was achieved. Subsequently, the as-obtained hydrophilic-hydrophobic patterned substrate was acted as a template for regulating the assembly behavior and spatial arrangement of polystyrene (PS) nanoparticles, leading to the generation of nanoparticle patterns with desired architectures. Especially, the assembly densities could be controlled via tuning the grafting density of patterned PEGMA brushes, which enabled the effective regulation of structural color on the patterned surface. On the basis of the spatiotemporal control of patterned hydrophilic region formation, the sequential assembly of different nanoparticles on the same substrate could be achieved, allowing for a multi-component nanoparticle pattern for structural color-based anticounterfeiting application. The presented technique for the creation of nanoparticle patterns/arrays exhibits a tremendous practical potential in various fields including high-throughput preparation of structural colors, anticounterfeiting/ information encryption, and optical hypersurfaces.

Understanding the evolution of ternary alloyed nanoparticles during reversible exsolution from double perovskite oxides

This work unveils the mechanism of FeCoNi alloy reversible exsolution from double perovskites via in situ synchrotron-based NAP-XPS and time-resolved XRD.

Metal-Doped ZIF-8 Derived Hollow Carbon for High-Performance Lithium-Sulfur Batteries

Lithium-ion (Li-ion) batteries have been ubiquitously utilized in the modernized world in portable electronic, electrical vehicles, and grid-scale energy storage. However, demand satisfaction for traditional Li-ion batteries is becoming difficult due to their limited capacity and energy density. Moreover, there are challenges related to the availability of non-renewable critical materials for Li-ion batteries such as Co, Ni, and graphite, and environmental pollution during battery creation and recycling. Further neglect of these problems will lead to dramatic consequences at which batteries will become a part of the environmental problems but not a solution to these problems as they should be. Therefore, it is highly imperative to explore novel battery systems that show high energy density, low production cost and low environmental pollution during production, use and recycling. One of the most promising candidates is the lithium-sulphur (LiS) battery, which offers various advantages such as high energy density, high theoretical specific capacity, and affordable cost, because of the high availability of elemental sulphur and carbon used in this type of battery. The theoretical gravimetric energy density of LiS batteries is 2567 Wh/kg which is 4.5 times higher than the energy density of conventional Li-ion batteries. Despite the richness of sulphur in the Earth’s crust and its prominent merits in energy density and cost, several problems have restricted the development of LiS batteries for commercialization. The most notorious and intractable problem is the high solubility of the sulphur species (Li2Sx, 3≤x≤8) in common Li-ion battery electrolytes that leads to the so-called lithium polysulfide (LiPS) shuttle effect and loss of battery capacity, Li metal anode corrosion, and low coulombic efficiency during interaction of the LiPS with Li metal anode. The most prospective solution to address the above drawbacks is sulphur incorporation with a porous, high-conductive carbon host that will tolerate sulphur volume expansion, improve the conductivity of the electrode, prevent the shuttle effect, and allow reversible lithium-ion migration during charging and discharging.However, to achieve the excellent operation performances of the porous carbon host its properties should be carefully tuned and the LiPS absorption ability of the carbon host should be improved for example by metal oxide doping. Many different strategies for the creation of the required material were proposed in recent years. Unfortunately, many proposed synthetic methods require a hard template to provide fine control of the pore distribution in the materials, which is a significant drawback as in this case harsh conditions are required for template removal. In addition, the formation of doped carbons with good electrical conductivity often demands high temperatures, simultaneously causing the undesirable reduction of metal cations to their metallic state followed by the aggregation to form nanoparticles, together with the collapse of the carbon matrices. Therefore, it still urgently needs to find a new strategy to produce a porous carbon host for the sulfur with fine porosity and good lithium polysulfide absorption ability, which purpose to accelerate the successful commercialization of this battery technology on the market.In our current work, we are investigating the possibility to synthesize finely dispersed metal oxide catalysts on hollow N-doped porous carbon capsules produced from zeolitic imidazolate framework (ZIF-8). The coating of the ZIF-8 with metal–tannic acid coordination polymer allows to uniformly dispersed metal oxide nanoparticles, such as Fe2O3, MnO, CoO etc., on hollow carbon capsules after the pyrolysis process. Moreover, the carbon produced by ZIF-8 pyrolysis is expected to be both doped with nitrogen and highly porous, which should have a positive effect on the maximum sulfur loading possibility in the carbon host and lithium polysulfide absorption ability. In addition, the used approach for the synthesis of the hollow N-doped porous carbon allows the distribution of multicomponent metal oxide nanoparticles on the surface of the hollow carbon capsules, which may have a synergetic effect and improve the lithium polysulfide absorption ability of the produced materials. The structural, compositional, and morphological properties of the created material are investigated using SEM, EDS, XPS, Raman spectroscopy, FTIR and TGA techniques. The effect of the different metal oxide nanoparticles and their combinations on the lithium polysulfide absorption ability of the synthesized materials are investigated by analysis of the electrochemical performances of the Li-S batteries, where synthesized material was used as the sulfur host during the creation of the Li-S battery cathode.

Light-to-Heat Conversion of Optically Trapped Hot Brownian Particles.

Anisotropic hybrid nanostructures stand out as promising therapeutic agents in photothermal conversion-based treatments. Accordingly, understanding local heat generation mediated by light-to-heat conversion of absorbing multicomponent nanoparticles at the single-particle level has forthwith become a subject of broad and current interest. Nonetheless, evaluating reliable temperature profiles around a single trapped nanoparticle is challenging from all of the experimental, computational, and fundamental viewpoints. Committed to filling this gap, the heat generation of an anisotropic hybrid nanostructure is explored by means of two different experimental approaches from which the local temperature is measured in a direct or indirect way, all in the context of hot Brownian motion theory. The results were compared with analytical results supported by the numerical computation of the wavelength-dependent absorption efficiencies in the discrete dipole approximation for scattering calculations, which has been extended to inhomogeneous nanostructures. Overall, we provide a consistent and comprehensive view of the heat generation in optical traps of highly absorbing particles from the viewpoint of the hot Brownian motion theory.

Microstructure and mechanical properties of multi-component nano oxide-dispersion strengthened RAFM steel fabricated via laser powder bed fusion

Y4Zr3O12 multi-component nanoparticles prepared by sol–gel method were adsorbed on the surface of gas-atomized reduced activation ferritic/martensitic (RAFM) steel powder. This mixture powder was then utilized in the fabrication of oxide-dispersion strengthened (ODS) RAFM steel through laser powder bed fusion. The microstructure of the ODS RAFM steel comprised a combination of columnar ferrite grains and martensitic laths. The Y4Zr3O12 nanoparticles were homogeneously distributed in the matrix, with an average size of 36.3 nm and a high density of 2.49 × 1020/m3. The results of the mechanical properties tests revealed that the additively manufactured ODS RAFM steel exhibited a good balance of strength and elongation.

Biosynthesis of ternary NiCoFe2O4 nanoflowers: investigating their 3D structure and potential use in gene delivery

Multicomponent nanoparticle systems are known for their varied properties and functions, and have shown potential as gene nanocarriers. This study aims to synthesize and characterize ternary nickel–cobalt-ferrite (NiCoFe2O4) nanoparticles with the potential to serve as gene nanocarriers for cancer/gene therapy. The biogenic nanocarriers were prepared using a simple and eco-friendly method following green chemistry principles. The physicochemical properties of the nanoparticles were analyzed by X-ray diffraction, vibrating sample magnetometer, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller. To evaluate the morphology of the nanoparticles, the field emission scanning electron microscopy with energy dispersive X-Ray spectroscopy, high-resolution transmission electron microscopy imaging, and electron tomography were conducted. Results indicate the nanoparticles have a nanoflower morphology with a mesoporous nature and a cubic spinel structure, where the rod and spherical nanoparticles became rose-like with a specific orientation. These nanoparticles were found to have minimal toxicity in human embryonic kidney 293 (HEK-293 T) cells at concentrations of 1 to 250 µg·mL–1. We also demonstrated that the nanoparticles could be used as gene nanocarriers for delivering genes to HEK-293 T cells using an external magnetic field, with optimal transfection efficiency achieved at an N/P ratio of 2.5. The study suggests that biogenic multicomponent nanocarriers show potential for safe and efficient gene delivery in cancer/gene therapy.Graphical

Cucurbit[8]uril Induced Molecular Folding Cascade Assembly for NIR Targeted Cell Imaging

AbstractA macrocyclic confinement‐activated green phosphorescence and two‐photon near‐infrared (NIR) fluorescence supramolecular cascade assembly is constructed by multivalent interaction based on the alkyl‐bridged triphenylamine‐vinyl pyridine salts (BTPA), cucurbit[8]uril (CB[8]), β‐cyclodextrin‐grafted hyaluronic acid (HACD), and 4‐bromophenyl pyridine salt and CB[8] complex (PY/CB[8]). Taking advantage of CB[8]‐induced macrocyclic confinement and molecular folding, the fluorescence of BTPA is effectively redshifted by 30 nm from 720 to 750 nm. Subsequently, HACD, a cancer cell targeting agent, is co‐assembled with a BTPA/CB[8] supramolecular folder to form a nanoparticle, further enhancing NIR fluorescence from 750 nm up to 810 nm through cascade confinement. Upon introduction of the 2:1 complex PY/CB[8], multicomponent nanoparticles are fabricated, not only showing efficient NIR fluorescence with an increase in quantum yield from 7.21% to 22.92% but also endowing green phosphorescence emission, which is successfully applied for two‐photon cancer cell‐targeted imaging to shield background interference from fluorescent and phosphorescent resources.

Recent Advances in the Development of Drug Delivery Applications of Magnetic Nanomaterials.

With the predicted rise in the incidence of cancer, there is an ever-growing need for new cancer treatment strategies. Recently, magnetic nanoparticles have stood out as promising nanostructures for imaging and drug delivery systems as they possess unique properties. Moreover, magnetic nanomaterials functionalized with other compounds can lead to multicomponent nanoparticles with innovative structures and synergetic performance. The incorporation of chemotherapeutic drugs or RNA in magnetic drug delivery systems represents a promising alternative that can increase efficiency and reduce the side effects of anticancer therapy. This review presents a critical overview of the recent literature concerning the advancements in the field of magnetic nanoparticles used in drug delivery, with a focus on their classification, characteristics, synthesis and functionalization methods, limitations, and examples of magnetic drug delivery systems incorporating chemotherapeutics or RNA.

Thermal stability and oxidation resistance of non-equimolar ratio AlTiVCrNb refractory high-entropy alloys

In this work, we investigated the thermal stability, oxidation resistance and high temperature mechanical properties of refractory high entropy alloys Ti75Al10V5Cr5Nb5, Ti67Al12V7Cr7Nb7 and Ti55Al15V10Cr10Nb10(at.%). It is found that the second phase would be precipitated and occurs order-disorder transformation in refractory high entropy alloys at high temperature. The HCP phase produced orderly B2 phase and decreased the orderly B2 phase precipitation with the increasement of temperature in Ti67Al12V7Cr7Nb7 and Ti55Al15V10Cr10Nb10. According to the oxidation kinetics of high entropy alloys after 100h oxidation at 800 °C, the oxidation index factor n is between 1.1 and 1.2 and the degree of oxidation is between oxidized and inoxidized, all three refractory high entropy alloys formed oxides with rutile structure, the Ti67Al12V7Cr7Nb7 being less oxidation resistant due to the generation of Nb2O5 which is less stable at high temperature. Ti67Al12V7Cr7Nb7 has a yield strength of 522 MPa with 50% elongation at 650 °C. Ti75Al10V5Cr5Nb5 and Ti67Al12V7Cr7Nb7 have lower strength but 150% deformation without fracture when stretched at 750 °C. The multi-component intermetallic compound nanoparticles formed by the second phase and ordered phase together in the refractory high entropy alloys have an Orowan strengthening effect, to improve the mechanical properties at high temperature since it effectively prevents dislocation movement and stores dislocations.

Electron beam melting of (FeCoNi)86Al7Ti7 high-entropy alloy

The development of traditional alloy materials has reached the bottleneck due to the constructive interaction between strength and plasticity. Hence, novel alloy systems like (FeCoNi)86Al7Ti7 high-entropy alloys (HEAs) were fabricated using selective electron beam melting (SEBM). The (FeCoNi)86Al7Ti7 HEA dominantly consisted of ordered L12 and disordered fcc matrix phases. The bottom surface (SEBM-bottom)) of the (FeCoNi)86Al7Ti7 HEA blocks presents an equiaxed microstructure; however, coarse columnar grains across layers were observed along the building direction (SEBM-side). Island-like precipitates (ILPs) are distributed evenly within the equiaxed grain. The boundaries of columnar grains and high-density multicomponent cubic nanoparticles (MCCNPs) are dispersed uniformly in the matrix. A strong< 100 > // building direction (BD) fiber texture can be observed. The (FeCoNi)86Al7Ti7 HEA exhibits superior strengths of 2048 MPa and up to 12% ductility at ambient temperature. However, the SEBM (FeCoNi)86Al7Ti7 HEA exhibits anisotropy in its mechanical properties.

Ordering-Dependent Hydrogen Evolution and Oxygen Reduction Electrocatalysis of High-Entropy Intermetallic Pt4 FeCoCuNi.

Disordered solid-solution high-entropy alloys have attracted wide research attention as robust electrocatalysts. In comparison, ordered high-entropy intermetallics have been hardly explored and the effects of the degree of chemical ordering on catalytic activity remain unknown. In this study, a series of multicomponent intermetallic Pt4 FeCoCuNi nanoparticles with tunable ordering degrees is fabricated. The transformation mechanism of the multicomponent nanoparticles from disordered structure into ordered structure is revealed at the single-particle level, and it agrees with macroscopic analysis by selected-area electron diffraction and X-ray diffraction. The electrocatalytic performance of Pt4 FeCoCuNi nanoparticles correlates well with their crystal structure and electronic structure. It is found that increasing the degree of ordering promotes electrocatalytic performance. The highly ordered Pt4 FeCoCuNi achieves the highest mass activities toward both acidic oxygen reduction reaction (ORR) and alkaline hydrogen evolution reaction (HER) which are 18.9-fold and 5.6-fold higher than those of commercial Pt/C, respectively. The experiment also shows that this catalyst demonstrates better long-term stability than both partially ordered and disordered Pt4 FeCoCuNi as well as Pt/C when subject to both HER and ORR. This ordering-dependent structure-property relationship provides insight into the rational design of catalysts and stimulates the exploration of many other multicomponent intermetallic alloys.