Search Results (191)

In order to meet the ever-growing demand in modern power electronics, the advanced soft magnetic materials (SMMs) are required to exhibit both excellent soft magnetic performance and mechanical properties. In this work, the effects of an annealing treatment on the soft magnetic properties, mechanical properties and microstructure of the Fe_24.94Co_24.94Ni_24.94Al_24.94Si_0.24 high-entropy alloy (HEA) are investigated. The as-cast HEA consists of a body-centered cubic (BCC) matrix phase and spherical B2 nanoprecipitates with a diameter of approximately 5 nm, where a coherent relationship is established between the B2 phase and the BCC matrix. After annealing at 873 K, the alloy retains both the BCC and B2 phases, with their coherent relationship preserved; besides the spherical B2 nanoprecipitates, rod-shaped B2 nanoprecipitates are also observed. After the annealing treatment, the saturation magnetization (M_s) of the alloy varies slightly within the range of 103–113 Am²/kg, which may be induced by the precipitation of this rod-shaped nanoprecipitate phase in the alloy. The increase in the coercivity (H_c) of annealed HEA is due to the inhomogeneous grain distribution, increased lattice misfit and high dislocation density induced by the annealing. The nanoindentation result reveals that the hardness after annealing at 873 K exhibits a 25% improvement compared with the hardness of as-cast HEA, which is mainly due to dislocation strengthening and precipitation strengthening. This research finding can provide guidance for the development of novel ferromagnetic HEAs, so as to meet the demands for materials with excellent soft magnetic properties and superior mechanical properties in the field of sustainable electrical energy. Full article

In Al–Fe alloys, the mechanical properties are determined by the morphology of iron-rich phases. In this work, AA8176(Al-1Fe)-nY (n = 0, 0.3, 0.5, 0.7, and 0.9 wt.%) alloys were prepared by the cast method. The effects of yttrium (Y) addition on the microstructure and mechanical properties of AA8176 alloy were studied using various techniques including optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), cooling curve analysis and tensile tests. The results revealed that the optimal refinement effect was achieved when the amount of Y content was 0.5 wt.%. When the Y content increased from 0 to 0.5 wt.%, the coarse needle-like Al₁₃Fe₄ phases were gradually transformed into short rod-like morphology and some fine Al₁₀Fe₂Y phases were formed around the Al₁₃Fe₄ phases. The average length of iron-rich phases was decreased from 10.01 μm to 2.65 μm. Additionally, as the Y content increased from 0 to 0.5 wt.%, the secondary dendrite arm spacing (SDAS) of AA8176 alloy was reduced from 31.33 μm to 20.24 μm. Furthermore, the mechanical properties of the AA8176 alloy were improved due to the modified microstructure. With the addition of 0.5 wt.% Y, the ultimate tensile strength, yield strength, elongation, and Vickers hardness were improved to 96.86 MPa, 57.21 MPa, 23.1%, and 30.55 HV, respectively, compared to 84.47 MPa, 50.71 MPa, 18.6%, and 27.28 HV for the unmodified AA8176 alloy. It is proposed that the growth of α-Al dendrite and Al₁₃Fe₄ phases were effectively inhibited by segregation of Y atoms around α-Al dendrite and Al₁₃Fe₄ phases during solidification. And the Al₁₀Fe₂Y phases were formed by these Y atoms with Al and Fe elements. However, the formation of coarse Al₁₀Fe₂Y phases was promoted by excessive Y content, resulting in a substantial degradation in mechanical properties. Full article

This research focuses on the investigation of microstructure, deformation, and superplastic behavior in wide range of strain rates of novel crossover Al-Zn-Mg-Cu alloy with Y/Er. The precipitation and superplastic behavior of the Al-Zn-Mg-Cu-Zr-Cr-Ti with Er/Y and Fe/Si impurities alloys have been studied. The microstructure of the alloys with nano-sized precipitates and micron-sized particles allows obtaining a micrograin stable microstructure. The spherical D0₂₃-Al₃(Er,Zr) precipitates with a diameter of about 20 nm and rod-like crystalline and qusicrystalline E (Al₁₈Mg₃Cr₂) precipitates with a thickness of about 20 nm and length of about 150–200 nm were identified by transmission electron microscopy. The superplastic deformation behaviors were investigated under different temperatures of 460–520 °C and different strain rates of 3 × 10⁻⁴ to 3 × 10⁻³ s⁻¹. The microstructure observation shows that uniform and equiaxed grains can be obtained by dynamic recrystallization before superplastic deformation. The alloy with Y exhibits inferior superplastic properties, while the alloy with Er has an elongation of more than 350% at a rate of 1 × 10⁻³ s⁻¹ and a temperature of 510 °C. Full article

This study investigates the Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ alloy designed to enhance glass-forming ability. The alloy was synthesized by arc melting and examined using infrared thermography, differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). Thermographic measurements revealed a temperature arrest at ~1007 K associated with eutectic crystallization, accompanied by contraction visible as a flattened ingot surface. DSC confirmed the dominant eutectic transformation (−170.7 J/g). Compared with the previously studied Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ alloy, this composition showed a simplified transformation sequence and a larger eutectic fraction. DSC of melt-spun ribbons demonstrated a three-step crystallization (659 K, 699 K, 735–773 K, completion ~820 K) with a total enthalpy of 180.4 J/g. The broad crystallization interval (ΔTc ≈ 161 K) indicates enhanced thermal stability compared with simpler Ni–P or Fe–Ni–P–C alloys. SEM/EDS observations revealed eutectic colonies with predominantly rod-like morphology and chemical partitioning in inter-colony regions, favoring precipitation of transition metal phosphides. XRD confirmed four crystalline phases (Fe–Ni, CrCoP, Ni₃P, MnNiP) in ingots, while ribbons exhibited a fully amorphous structure. These findings demonstrate that Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ possesses good glass-forming ability but forms multiple phosphides under slower cooling. Precise cooling control is thus essential for tailoring its amorphous or crystalline state. Full article

This work presents a comparative study on the structural, microstructural, and functional properties of a novel lead-free solid solution based on (1−x)(0.95(Bi_0.5Na_0.5)TiO₃–0.05BaTiO₃)–x(0.5Ba_0.7Ca_0.3TiO₃–0.5BaTi_0.8Zr_0.2O₃), abbreviated as (1−x)(BNT–5BT)–xBCZT, with x values ranging from 0 to 0.20. Two different synthesis routes were evaluated: a direct route, where all raw materials were mixed and processed in a single step, and an indirect route, where BNT–5BT and BCZT were pre-synthesized separately and later combined. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of single-phase perovskite structures, with progressively increasing tetragonality as x increased. Field-emission scanning electron microscopy (FE-SEM/EDS) revealed dense microstructures and secondary rod-like phases whose morphology and amount evolved with composition. Dielectric measurements indicated an enhanced relaxor behavior with increasing BCZT content, evidenced by a shift in the T_F–R with frequency. The direct route resulted in more efficient dopant incorporation, leading to stronger dielectric relaxation, reduced hysteresis losses, and improved energy storage performance. The maximum energy efficiency (η) reached 43.7% for x = 0.075 via the direct route, compared to 38.0% for the same composition prepared by the indirect route. The maximum recoverable energy density (W_rec) reached 0.42 J·cm⁻³ for x = 0.075 via the direct route (vs. 0.40 J·cm⁻³ for the indirect route), with corresponding peak energy efficiencies of 43.7% and 38.0%, respectively. These findings demonstrate that (1−x)(BNT–5BT)–xBCZT ceramics synthesized via the direct route constitute a promising and scalable approach for high-efficiency, lead-free dielectric capacitors. Full article

In this study, we fabricated Fe-25Ni-15Cr alloy rods via vacuum induction melting, electroslag remelting, forging, hot rolling, and annealing. We systemically investigated the influence of varying cold-drawing deformation levels (10–60%) on microstructure evolution and mechanical properties, which were characterized by a variety of multi-scale characterization techniques, including optical microscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The results show that when the cumulative deformation amount is less than 30%, the hardness, tensile strength, and yield strength increase significantly with the increase in deformation amount, while the elongation continues to decline; when the cumulative deformation amount exceeds 30%, the rates of increase in hardness and strength decrease significantly; and when the deformation amount increases to 50%, dislocation density accumulates preferentially at the grain boundaries and forms a cellular substructure, while the texture orientation gradually stabilizes from random distribution to the <111> direction. This alloy rod exhibits three strengthening mechanisms during cold drawing: grain refinement, second-phase precipitation, and work hardening. A predictive model for tensile strength is derived through theoretical calculations. This work has guiding significance for establishing a cold-drawing process window without intermediate annealing. Full article

Bacterial leaf blight (BLB), a destructive disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo), continues to limit rice productivity worldwide. Although biologically synthesized zinc oxide nanoparticles (ZnO NPs) have been extensively investigated, knowledge regarding the antibacterial activity and biocompatibility of commercially available ZnO NPs is still limited. In this study, commercial ZnO NPs were systematically characterized and evaluated for their antibacterial mechanisms and biocompatibility in mammalian cells. FE-SEM and TEM analyses revealed irregular polyhedral, hexagonal, and short rod-like morphologies with an average particle size of ~33 nm, consistent with crystallite sizes estimated by XRD. The nanoparticles exhibited pronounced antibacterial activity against Xoo, with a minimum inhibitory concentration (MIC) of 16 µg/mL and a clear dose-dependent response. Mechanistic assays confirmed multifaceted bactericidal actions involving membrane disruption, ROS generation, Zn²⁺ release, and ultrastructural damage. Biocompatibility testing in human dermal fibroblasts showed enhanced proliferation at 8–32 µg/mL, no cytotoxicity up to 256 µg/mL, and reduced viability only at ≥512 µg/mL. These findings represent the first mechanistic evaluation of commercial ZnO NPs against Xoo, together with cytotoxicity assessment in mammalian cells, highlighting their structural distinctness and dual functionality that combine potent antibacterial activity with minimal mammalian cytotoxicity. Overall, the results underscore their potential as safe nanobiocontrol agents for sustainable rice disease management. Full article

This study presented a comprehensive finite element (FE) investigation into the flexural behavior of RC T-beams strengthened in the negative moment region using near-surface mounted (NSM) carbon-fiber-reinforced polymers (CFRP) rods. A three-dimensional nonlinear FE model was developed and validated against experimental data, achieving close agreement with normalized mean square error values as low as 0.006 and experimental-to-numerical ratios ranging from 0.95 to 1.04. The validated model was then employed to conduct a systematic parametric analysis considering CFRP rod diameter, concrete compressive strength, longitudinal reinforcement ratio, and FRP material type. The results showed that increasing CFRP diameter from 6 to 10 mm enhanced ultimate load by up to 47.51% and improved stiffness by 1.48 times. Higher concrete compressive strength contributed to stiffness gains exceeding 50.00%, although this improvement was accompanied by reductions in ductility. Beams with reinforcement ratios up to 2.90% achieved peak loads of 309.61 kN, but ductility declined. Comparison among FRP materials indicated that CFRP and AFRP offered superior strength and stiffness, whereas BFRP provided a more balanced combination of strength and deformation capacity. Full article

Fe–Cr–Nb–Al–C alloy coatings were firstly fabricated on a high-carbon forged steel surface via coaxial laser cladding. The morphological evolution with varying Nb contents and wear mechanisms of the coatings were systematically investigated through comprehensive analysis. The results indicate that Nb content critically governs the coating microstructure and mechanical properties. At low Nb levels, coarse grain-boundary networks of (Fe,Cr) solid solution embrittled by Cr₂₃C₆ are formed. Moderate Nb addition produces finely dispersed rod-shaped NbC precipitates. At higher Nb levels, the morphology evolves into a segregated martensite–ferrite dual-phase structure. The coating wear rate exhibits a parabolic dependence on Nb content, initially decreasing with moderate addition and then increasing with further Nb. Consequently, optimal wear resistance is achieved at a critical Nb content (3 wt.%) that establishes an optimal balance between NbC precipitation and phase uniformity, thereby minimizing debris generation and spalling. Full article

This study investigates the fabrication of a Cu-Mn-Al alloy coating on 27SiMn steel using Cold Metal Transfer (CMT) technology with an innovative Ar-B(OCH₃)₃ mixed shielding gas, focusing on the effect of the gas flow rate (5–20 L/min). The addition of B(OCH₃)₃ was found to significantly enhance process stability by improving molten pool wettability, resulting in a wider cladding layer (6.565 mm) and smaller wetting angles compared to pure Ar. Macro-morphology analysis identified 10 L/min as the optimal flow rate for achieving a uniform and defect-free coating, while deviations led to oxidation (at low flow) or spatter and turbulence (at high flow). Microstructural characterization revealed that the flow rate critically governs phase evolution, with the primary κI phase transforming from dendritic/granular to petal-like/rod-like morphologies. At higher flow rates (≥15 L/min), increased stirring promoted Fe dilution from the substrate, leading to the formation of Fe-rich intermetallic compounds and distinct spherical Fe phases. Consequently, the cladding layer obtained at 10 L/min exhibited balanced and superior properties, achieving a maximum shear strength of 303.22 MPa and optimal corrosion resistance with a minimum corrosion rate of 0.02935 mm/y. All shear fractures occurred within the cladding layer, demonstrating superior interfacial bonding strength and ductile fracture characteristics. This work provides a systematic guideline for optimizing shielding gas parameters in the CMT cladding of high-performance Cu-Mn-Al alloy coatings. Full article

This study investigates the structural and magnetic properties of ultra-high coercivity (Fe₈₀B₁₄Nb₆)_0.88Dy_0.12 alloys, doped with 0.5–5 at.% of selected metallic additions: magnetic (Ni, Co) and non-magnetic (Pt, Cu) elements. Material characterization involved both structural and magnetic measurements. Alloys containing dopant concentrations up to 2 at.% exhibited similar phase compositions, with the Dy₂Fe₁₄B compound being dominant. Magnetic hysteresis loops revealed a superposition of two components: magnetically soft and hard phases. A significant change in magnetic properties was observed within the 0.5 to 1 at.% dopant concentration range. Notably, the addition of 0.5 at.% Ni increased the apparent anisotropy field from 5.2 T to 7.5 T. Furthermore, 0.5 at.% Pt led to an increase in the coercive field from 4.6 T to 5.5 T. These additions influenced crystallization, resulting in the formation of a more regular microstructure without submicrometric dendrite branches, when compared to the base alloy. Full article

Prestressed concrete structures are facing serviceability challenges due to rising live loads, material degradation, and seismic demands. Retrofitting with carbon fiber-reinforced polymer (CFRP) offers a cost-effective alternative to full replacement. This study presents a finite element (FE) modeling framework to simulate the seismic performance of prestressed concrete T-beams retrofitted in the negative moment region using near-surface-mounted (NSM) CFRP rods and sheets. The model incorporates nonlinear material behavior and cohesive interaction at the CFRP–concrete interface and is validated against experimental benchmarks, with ultimate load prediction errors of 4.41% for RC T-beams, 0.49% for prestressed I-beams, and 1.30% for prestressed slabs. A parametric investigation was conducted to examine the influence of CFRP embedment depth and initial prestressing level under three seismic conditions. The results showed that fully embedded CFRP rods consistently improved the beams’ ultimate load capacity, with gains of up to 10.84%, 16.84%, and 14.91% under cyclic loading, near-fault ground motion, and far-field ground motion, respectively. Half-embedded CFRP rods also prove effective and offer comparable improvements where full-depth installation is impractical. The cyclic load–displacement histories, the time–load histories under near-fault and far-field excitations, stiffness degradation, and damage contour analysis further confirm that the synergy between full-depth CFRP retrofitting and optimized prestressing enhances structural resilience and energy dissipation under seismic excitation. Full article

This study is focused on the hydrothermal synthesis of iron–manganese oxide nanostructures, focusing on the influence of Fe:Mn precursor ratios, temperature, and reaction time on phase formation, morphology, and structural characteristics. Three molar ratios (Fe:Mn = 2:1, 1:1, and 1:2) were explored under variable conditions (80 °C, 120 °C, and 200 °C; 4, 12, and 24 h). X-ray diffraction (XRD) analysis revealed distinct phase selectivity depending on precursor composition: FeMn₂O₄ was obtained with 1:2 ratio, Fe₃Mn₃O₈ with 1:1, and Fe₂MnO₄ with 2:1, each without phase mixing. Scanning electron microscopy (FESEM) showed a pronounced effect of temperature and time on nanoparticle morphology, ranging from compact agglomerates to well-defined rod-like structures at 200 °C/24 h. Dynamic light scattering (DLS) indicated narrow size distributions for samples synthesized at 120 °C/12 h, with hydrodynamic diameters between 20 and 50 nm. Raman spectroscopy confirmed the presence of characteristic vibrational modes of spinel-type structures and validated structural integrity. High-resolution transmission electron microscopy (HRTEM) evidenced well-ordered lattice fringes with interplanar spacings of ~0.48–0.52 nm, consistent with spinel phases and indicative of high crystallinity. These findings demonstrate that controlled atomic binding and thermal parameters enable selective synthesis of pure iron–manganese oxide phases with tailored morphologies, offering a scalable route for designing advanced functional materials in catalysis, energy, and biomedical applications. Full article

Fe-Cr-Nb-C wear-resistant alloy coatings were successfully fabricated on high-carbon forged steel via coaxial powder feeding laser cladding. The evolution of microstructure and wear resistance with varying Nb content was systematically investigated. The results indicate that appropriate NbC addition markedly modifies the distribution of grain and boundary carbides. As Nb content increases from 2.5 wt% to 3.5 wt%, nanoscale rod-like NbC precipitates form uniformly along boundaries, effectively suppressing the formation of brittle Cr₂₃C₆ precipitation. Semi-coherent NbC/matrix interfaces and NbC-induced grain refinement reduce adhesive/abrasive wear, thereby improving hardness and wear resistance. At 4.5 wt% Nb, discrete micron-sized NbC particles form within the grains, yielding optimal performance. However, excessive Nb (≥5.5 wt%) causes NbC agglomeration, inducing stress concentrations and large spallation pits that deteriorate wear resistance. This work highlights NbC morphology as a key factor for tailoring coating properties. Full article

This study explores the critical role of airborne nanoparticle shape in air filtration performance, with direct relevance to the field of nanomaterials production. Aerosol particles ranging from 40 to 250 nm—including spherical Fe₂O₃, cubic MgO, straight rod-shaped ZnO, and curved or clustered COOH-functionalized nanotubes—were synthesized and tested to assess shape-dependent filtration behavior. The results indicate that the effect of particle morphology on filtration efficiency becomes markedly pronounced at larger particle sizes. For instance, at 250 nm, filtration efficiency differed by as much as 30% between spherical Fe₂O₃ and rod-shaped ZnO particles. These findings have substantial implications for industries engaged in large-scale nanomaterial synthesis, particularly where anisotropic or rod-like particles are prevalent. The potential for higher-than-anticipated atmospheric release of such particles underscores the need for refined environmental controls and monitoring. Furthermore, the current practice of using primarily spherical particles in air filter certification tests may require reconsideration to ensure accuracy and applicability to real-world scenarios involving non-spherical nanomaterials. Full article