Search Results (2,022)

Improving the efficiency of electric vehicle traction motors requires non-oriented silicon steels with low core loss and favorable magnetic induction. This study aims to clarify the influence of annealing temperature on the microstructure, texture, and magnetic properties of a 3.2%Si–0.9%Al steel, providing guidance for process optimization. Optical metallography, X-ray diffraction, and electron backscatter diffraction were employed to characterize the evolution. Recrystallization was completed between 620 °C and 720 °C, during which fine recrystallized grains replaced the deformed structure, accompanied by the nucleation of {111}<112> and {114}<481> grains. With further annealing from 850 °C to 1050 °C, grain growth occurred, resulting in an α*-fiber texture dominated by {114}<481>. The fraction of high-angle {114}<481> grains increased, while low-angle {111}<112> grains decreased. This microstructural evolution significantly influenced the magnetic properties of non-oriented electrical steel. The P_1.5/50 and P_1.0/400 core losses reached minimum values of 2.02 W/kg and 16.48 W/kg at 1010 °C and 930 °C, respectively, while B₅₀ decreased slightly from 1.670 T to 1.652 T. These findings indicate that precise control of the annealing temperature is an effective strategy to tailor microstructure and texture, thereby optimizing the magnetic properties of non-oriented electrical steel. Full article

There are many obstacles to the industrial application of CO₂ hydrogenation reduction technology, the most important of which is the high economic cost. The purpose of this study is to explore the interaction mechanism between the active component CuO-ZnO-Al₂O₃(CZA) and the zeolite carrier Zeolite Socony Mobil-5(ZSM-5), screen the simplified preparation method of catalysts with high catalytic performance, and further promote the industrial application of CO₂ hydrogenation reduction technology. In this study, the effects of the gas velocity of the feedstock, the reaction temperature, the content of acidic sites in the carrier, the filling amount of active component, and the mixing mode of the active component and the carrier on catalytic CO₂ hydrogenation reduction were investigated. The structure of the catalysts was analyzed by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The catalyst surface properties were analyzed by X-ray photoelectron spectroscopy (XPS), ammonia temperature programmed desorption (NH₃-TPD), hydrogen temperature programed reduction (H₂-TPR) and other characterization methods. The research found that the grinding treatment led to the insertion of CZA between ZSM-5 zeolite particles in CZA@HZ5-20-GB, which was prepared via grinding both CZA and H-ZSM-5 with an Si/Al ratio of 20, inhibiting the action of strongly acidic sites in the zeolite, resulting in only CO and MeOH in the catalytic products, with no Dimethyl Ether (DME) generation. Full article

As the most commercially developed metal additive process, laser powder bed fusion (LPBF) is vital to advancing several industry sectors, enabling high-precision part production across aerospace, biomedical, and manufacturing industries. Al 7075 alloy offers low density and high-specific strength yet faces LPBF challenges such as hot cracking and porosity due to rapid solidification, thermal gradients, and a wide freezing range. To address these challenges, this study proposes an integrated computational and experimental framework to enhance the LPBF processability of Al 7xxx alloys by compositional modification. Using the Calculation of Phase Diagram approach, printable Al 7xxx compositions were designed by adding grain refiners (V and/or Ti) and a eutectic solidification enhancer (Mg) to Al 7075 alloy to enable grain refinement and eutectic solidification. Subsequent LPBF experiments and characterization tests, such as metallography (scanning electron microscopy), energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray micro-computed tomography, confirmed the production of refined microstructures with reduced defects. This study contributes to existing approaches for producing high-quality Al 7xxx alloy parts without significant compositional deviations using an integrated computational and experimental approach. Finally, aligning with the Materials Genome Initiative, this study contributes to the development and industrial adoption of advanced materials. Full article

The use of aluminum alloys in aerospace is limited by their poor weldability, making many incompatible with additive manufacturing (AM) processes like powder bed fusion—laser beam metal (PBF-LB/M), known as well as laser powder bed fusion. This incompatibility hinders the fabrication of complex, lightweight components. To overcome this, Aluminum Metal Matrix Composites (AMMCs) are formed by mechanically alloying the non-processable Al6082 base alloy with ceramic reinforcements; subsequently, Titanium Carbide (TiC) and Silicon Carbide (SiC) particles are developed. This approach induces microstructural changes necessary for AM compatibility. The influence of varying reinforcement contents (1–5 wt.%) on powder homogeneity, microstructural evolution (via Energy Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction), processability, and mechanical properties is systematically studied. The key finding is that metallurgical modification is a robust solution. TiC addition at 2 wt.% and 5 wt.% completely eliminated solidification cracking, achieving high processability. SiC substantially reduced cracking compared to the base alloy. These results demonstrate the potential of AMMCs to successfully translate conventional, non-weldable aluminum alloys into the realm of advanced additive manufacturing. Full article

Bulk metallic glasses (BMGs), classified as metastable materials, necessitate melt quenching at critical cooling rates higher than 10² K/s to kinetically bypass crystalline phase formation during solidification. Owing to this rapid quenching, the microstructure of BMGs can be regarded as melt quenched. This study examines how their melt state governs the thermal stability, structural characteristics, and plasticity behavior of Zr₅₀Cu₄₀Al₁₀ BMG. Rod samples were prepared via injection casting at controlled melt temperatures and suction casting. Experimental observations demonstrated a positive correlation between elevated melt temperatures and enhanced glass forming ability (GFA) along with improved thermal stability (T-A) in BMGs during processing. Structural analyses confirmed the glassy nature of the prepared BMGs with different melt states and revealed their temperature-dependent atomic-scale heterogeneity: the samples quenched at low melt temperatures exhibited significant Cu-rich clustering as determined via energy-dispersive X-ray spectroscopy (EDS) mapping, and those at high melt temperatures formed homogeneous structures. This structure heterogeneity was directly correlated with good plastic deformation behavior, i.e., the rod sample prepared at the lowest melt temperature achieved 9.7% plastic strain. The transition is attributed to liquid-liquid phase transition (LLPT): below the LLPT threshold, metastable Cu-rich clusters persist in the melt and are retained upon quenching, creating structural defects that facilitate shear band multiplication. These findings highlight melt temperature as a crucial factor in tailoring the structure characteristic and mechanical behavior of Zr₅₀Cu₄₀Al₁₀ BMGs. Full article

The global reliance on coal-fired power generation continues to produce vast quantities of fly ash, exceeding 500 million tons annually, with limited recycling rates. Given its high silica (SiO₂) and alumina (Al₂O₃) contents, fly ash represents a promising alternative raw material for sustainable refractory production. In this study, four aluminosilicate refractory castables were formulated using bauxite, calcined flint clay, kyanite, calcium aluminate cement, and microsilica, in which the fine fraction of flint clay was partially replaced by 0, 5, 10, and 15 wt.% fly ash. The specimens were dried at 120 °C and sintered at 850, 1050, and 1400 °C for 4 h. Their physical and mechanical properties were systematically evaluated, while phase evolution and microstructural development were analyzed through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the incorporation of 10 wt.% fly ash (10FAC) provided the optimal balance between densification and strength, achieving compressive strengths of 45.0 MPa and 65.3 MPa after sintering at 1050 °C and 1400 °C, respectively. This improvement is attributed to the formation of a SiO₂-rich liquid phase derived from fly ash impurities, which promoted the in-situ crystallization of acicular secondary mullite and enhanced interparticle bonding among corundum grains. The 10FAC castable also exhibited only a slight increase in apparent porosity (26.39%) compared with the reference (25.74%), indicating effective sintering without excessive vitrification. Overall, the study demonstrates the technical viability of using fly ash as a sustainable substitute for flint clay in refractory castables. The findings contribute to advancing circular economy principles by promoting industrial waste valorization and resource conservation, offering a low-carbon pathway for the development of high-performance refractory materials for structural and thermal applications in energy-intensive industries. Full article

We report a scalable route to hybrid aluminum matrix composites (AMCs) based on Al6060 (as-fabricated condition) reinforced with 2 wt.% TiB₂ and 1 wt.% microsilica, fabricated by ultrasonically assisted stir casting (UASC) followed by radial-shear rolling (RSR). Premixing and preheating of powders combined with acoustic cavitation/streaming during UASC ensured uniform, non-sedimentary particle dispersion and low-defect cast billets. X-ray diffraction of the as-cast composite shows fcc-Al with weak TiB₂ reflections and no reaction products; microsilica remains amorphous. Electron microscopy and EBSD after RSR reveal full erasure of cast dendrites, fine equiaxed grains, weakened texture, and a high fraction of high-angle boundaries due to the concurrent action of particle-stimulated nucleation (micron-scale TiB₂) and Zener pinning/Orowan strengthening (50–350 nm microsilica). Mechanical testing shows that, in the cast state—comparing cast monolithic Al6060 to the cast hybrid-reinforced composite—yield strength (YS) increases from 61.7 to 77.2 MPa and ultimate tensile strength (UTS) from 103.4 to 130.7 MPa, without loss of ductility. After RSR to Ø16 mm (cumulated true strain ≈ 0.893), the hybrid attains YS 101.2 MPa, UTS 150.6 MPa, and elongation ≈ 22.0%, i.e., comparable strength to rolled Al6060 (UTS 145.1 MPa) while restoring/raising ductility by ~9.7 percentage points. Microhardness follows the same trend, increasing from 50.2 HV0.2 to 73.1 HV0.2 when comparing the base cast condition with the rolled hybrid. The route from UASC to RSR thus achieves a favorable mechanical strength–ductility balance using an economical, eco-friendly oxide/boride hybrid reinforcement, making it attractive for formable AMC bar and rod products. Full article

This study investigated the variation in precipitation in Fe-25Cr-5Al-Ti-RE ferritic stainless steel under different quenching heat treatment temperatures. Quenching heat treatments were performed at five temperatures, namely 600 °C, 700 °C, 800 °C, 900 °C, and 1000 °C. To analyze the alloy’s microstructure and precipitation behavior, comprehensive characterization techniques were employed, including X-ray Diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrated that after quenching at these temperatures, the main precipitation in the alloy was a chromium-rich phase (α′), aluminum oxide (Al₂O₃), titanium carbide (TiC), and titanium nitride (TiN). Specifically, Al₂O₃ was detected exclusively after heat treatments at 800 °C, 900 °C, and 1000 °C, with its particle size ranging from 10 nm to 100 nm. During high-temperature heat treatment, aluminum atoms and oxygen atoms in the matrix interacted with each other, and fine Al₂O₃ particles precipitated through a solid-state phase transition. Regarding titanium-containing precipitates, TiC precipitated after heat treatments at 700 °C, 800 °C, and 900 °C, whereas TiN was only observed after the quenching treatment at 1000 °C. The size of TiC particles fell within the range of 100 nm to 400 nm, while TiN particles exhibited a significantly larger size, spanning from 5 μm to 10 μm. Thermodynamic and kinetic analyses revealed that at elevated temperatures, nitrogen (N) exhibited a relatively high diffusion coefficient in the matrix; meanwhile, titanium (Ti) demonstrated an extremely strong chemical affinity for N. Consequently, even when the N content in the alloy was at a low level, N tended to preferentially react with Ti rather than with carbon (C) to form TiN. Full article

CaO-Al₂O₃-Ce₂O₃ is a potential new-type basic metallurgical slag system for rare earth steel. To investigate the effects of CaF₂ on the melting point and equilibrium phase types of this slag system, the phase equilibrium relationships and extent of the liquid phase region of CaO-Al₂O₃-Ce₂O₃-CaF₂ slag system at 1300 °C, 1400 °C, and 1500 °C in C/CO were determined by the high-temperature phase equilibrium experiment, Scanning Electron Microscope-Energy Dispersive X-ray Spectrometer (SEM-EDX) and X-ray Diffraction (XRD), and the isothermal phase diagram was plotted. The experimental results show that within the composition range in this study, the slag system has five, seven, and six liquid–solid equilibrium coexistence regions at 1300 °C, 1400 °C, and 1500 °C. The involved multiphase equilibrium regions include five two-phase regions (i.e., Liquid + CaO, Liquid + CaO·2Al₂O₃, Liquid + 2CaO·Al₂O₃·Ce₂O₃, Liquid + 2CaO·3Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂), 4 three-phase regions (i.e., Liquid + CaO + 2CaO·Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂ + 2CaO·Al₂O₃·Ce₂O₃, Liquid + CaO·2Al₂O₃ + 2CaO·3Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂ + 2CaO·3Al₂O₃·Ce₂O₃), and 1 four-phase region (i.e., Liquid + CaO + 11CaO·7Al₂O₃·CaF₂ + 2CaO·Al₂O₃·Ce₂O₃). Meanwhile, based on liquid phase compositions under liquid–solid multiphase equilibrium, the slag system’s liquid phase ranges at the experimental temperatures were determined as follows: at 1300 °C: w(CaO)/w(Al₂O₃) = 0.42~0.92, w(Ce₂O₃) = 1.63%~8.02%, w(CaF₂) = 9.17%~21.46%; 1400 °C: 0.28~1.18, 0.9%~12.62%, 1.04%~23.34%, respectively; 1500 °C: 0.23~1.21, 0~14.42%, 0~26.32%, respectively. Full article

Aluminum doping can improve the phase stability of metastable compound Sm₂Fe₁₇C_x with a high carbon content (x > 1.5). We investigated the preferential site substitution of Al, chemical bonding, and structural stability in Sm₂(Fe,Al)₁₇C₃ using first-principle calculations. Our results reveal a strong correlation between the preferential substitution of Fe by Al and the atomic site chemical environment, which affects the overall phase stability. Specifically, Al preferentially occupies the 9d site in Sm₂(Fe,Al)₁₇C₃. At the same time, Al prefers the site 6c in its parent phase Sm₂(Fe,Al)₁₇. Partial replacement of Fe with Al leads to a more negative formation energy, indicating enhanced thermodynamic stability. Crystal Orbital Hamilton Population (COHP) and Crystal Orbital Bond Index (COBI) analysis suggest that insertion of carbon weakens the bonding strength of Sm-Fe (18f) and Sm-Fe (18h), resulting in metastability of Sm₂Fe₁₇C_x. Doping Al strengthens Al-Fe, Al-Sm, Sm-Fe (18f, 18h) and Fe–C bonding in Sm₂(Fe,Al)₁₇C₃, as revealed by calculated COHP and COBI. These effects contribute to improved phase stability in the Al-doped 2:17 interstitial compound. Full article

This study employs a combined approach of theoretical calculations and experimental validation to systematically optimize the alloy composition, aiming to mitigate the hot cracking susceptibility of an Al-3.0Ce-xCa-yMn alloy in laser powder bed fusion (LPBF) processing. Through advanced characterization techniques such as electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and mechanical property testing, the intrinsic relationship between microstructure and mechanical performance was thoroughly elucidated. Computational results revealed that the addition of Ca significantly lowered the eutectic precipitation temperature, thereby effectively reducing the hot cracking tendency while maintaining a stable volume fraction of the Al₁₁(Ce, Ca)₃ phase. The optimal mass fractions of calcium (Ca) and manganese (Mn) were determined to be 0.8% and 1.9%, respectively. Microstructural characterization indicates that the alloy consisted of an α-Al matrix embedded with Al-Ce-Ca ternary eutectic compounds, and nanoscale Al₆Mn spherical precipitates were uniformly distributed within the matrix. Mechanical property evaluations demonstrated that the Al-3Ce-0.8Ca-1.9Mn alloy exhibited an outstanding balance of strength and ductility at both room and elevated temperatures, with room temperature yield strength, tensile strength, and elongation values of 321 ± 15 MPa, 429 ± 8 MPa, and 10.9 ± 2.3%, respectively. This exceptional performance was attributed to a synergistic combination of multiple strengthening mechanisms including eutectic structure-induced strengthening, grain boundary strengthening due to ultrafine grains, and dislocation pinning strengthening caused by nano-sized Al₆Mn precipitates. Full article

To address the issues of insufficient capacity and difficult regeneration of adsorbents for phosphate removal from wastewater, in this study, FeOOH/Al₂O₃ adsorbents were successfully developed by in situ growing amorphous iron oxyhydroxide (FeOOH) within the pores of alumina (Al₂O₃) using a simple method. The physicochemical properties of FeOOH/Al₂O₃ adsorbents were characterized using X-ray Diffraction (XRD), N₂ adsorption/desorption analysis, and scanning electron microscopy (SEM). Additionally, their phosphate adsorption properties were comparatively investigated. The results revealed that FO-A-3, one of the FeOOH/Al₂O₃ samples prepared with Fe/Al molar ratio of 0.47, exhibited excellent adsorption capacity and a relatively fast adsorption rate, surpassing those of Al₂O₃ and amorphous FeOOH alone. The adsorption process of phosphate using FO-A-3 conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, with a maximum adsorption capacity of 131.00 mg/g. To tackle the problem of poor regeneration performance, this study innovatively proposed a repeatable and simple regeneration strategy. Experiments demonstrated that FO-A-3 maintained a relatively high adsorption capacity after four cycles of regeneration. Full article

The application of laser powder bed fusion (LPBF) to 7xxx-series aluminum alloys is fundamentally limited by hot cracking and porosity. This study demonstrates that adding 5 wt.% AlCoCrFeNi_2.1 high-entropy alloy (HEA) particles to 7075 aluminum alloy (AA7075) powder can effectively mitigate these issues. Microstructural characterization revealed that the HEA particles remained largely intact and formed a strong metallurgical bond with the α-Al matrix. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed that this bonding is facilitated via the in situ formation of new intermetallic phases at the particle/matrix interface. X-ray diffraction (XRD) identified these phases as primarily Al₅Co₂ and Fe₃Ni₂. A key consequence of this reinforced interface is a significant change in cracking behavior; optical microscopy (OM) showed that long, continuous cracks typical of AA7075 were replaced by shorter, deflected cracks in the composite. While porosity was not eliminated, the addition of HEA stabilized the process, yielding a consistent density improvement of 0.5–1.5% across the processing window. This microstructural modification resulted in a substantial ~64% increase in average microhardness, which increased from 96.41 ± 9.81 HV_0.5 to 158.46 ± 11.33 HV_0.5. These results indicate that HEA reinforcement is a promising route for engineering the microstructure and improving the LPBF processability of high-strength aluminum alloys. Full article

The development of porous carbon materials that meet the demands of commercial supercapacitors is challenging, primarily due to the requirements for high energy and power density, as well as large-scale manufacturing capabilities. Herein, we present a sustainable and cost-effective method for synthesizing N–O–S co-doped hierarchical porous carbons (designated as ALK_x) from ammonium lignosulfonate (AL), an industrial by–product. This process employs a low KOH/AL mass ratio (x ≤ 0.75) and a carbonization temperature of 900 °C. The resulting materials, ALK₀.₅₀ and ALK_0.75, exhibit an exceptionally high specific surface area (>2000 m² g⁻¹), a well-balanced micro-mesoporous structure, and tunable heteroatom content, which collectively enhance their electrochemical performance in both aqueous and ionic liquid electrolytes. Notably, ALK_0.75 features a heteroatom content of 13.2 at.% and a specific surface area of 2406 m² g⁻¹, owing to its abundant small mesopores. When tested as an electrode in a two–electrode supercapacitor utilizing a 6 M KOH electrolyte, it achieves a high specific capacitance of 250 F g⁻¹ at a current density of 0.25 A g⁻¹ and retains 197 F g⁻¹ even at 50 A g⁻¹, demonstrating remarkable rate capability. In contrast, ALK_0.50, characterized by a lower heteroatom content and an optimized pore structure, exhibits superior compatibility with the ionic liquid electrolyte EMIMBF₄. A symmetric supercapacitor constructed with ALK_0.50 electrodes attains a high energy density of 90.2 Wh kg⁻¹ at a power density of 885.5 W kg⁻¹ (discharge time of 60 s). These findings provide valuable insights into heteroatom doping and the targeted regulation of pore structures in carbon materials, while also highlighting new opportunities for the high-value utilization of AL. Full article

Hard Cr-Al-Si-B-(N) coatings were deposited in Ar and Ar–15%N₂ medium by d.c. magnetron sputtering of composite targets manufactured using self-propagating high-temperature synthesis. The structure of the coatings was studied by X-ray diffraction, scanning and transmission electron microscopy, energy dispersion spectroscopy, and glow discharge optical emission spectroscopy. The coating properties were determined by nanoindentation, scratch testing, and tribological pin-on-disc testing at room and elevated temperatures. The oxidation resistance and diffusion barrier properties of the coatings were also evaluated. The results obtained showed that non-reactive coatings had a coarse crystalline structure and contained Cr₅Si₃, CrB_x, and Cr₂Al phases. The introduction of nitrogen into the coating composition promoted crystallite refinement and structural amorphization. Non-reactive CrAl₄Si₁₁B₂₁ coatings had a maximum hardness up to 29 GPa and an elastic modulus up to 365 GPa. The introduction of nitrogen into the coating composition resulted in a 16–32% reduction in mechanical properties. The CrAl₆Si₁₂B₅N₂₅ coating, which exhibited maximal plasticity index H/E = 0.100 and resistance to plastic deformation H³/E² = 0.247 GPa, was characterized by a minimum wear rate Vw = 5.7 × 10⁻⁶ mm³N⁻¹m⁻¹ and a friction coefficient of 0.47. While the CrAl₁₈Si₁₁B₅N₂₆ coating demonstrated a record level of oxidation resistance and successfully resisted oxidation up to a temperature of 1300 °C. Full article