Search Results (489)

To ensure the sustainability of alloy-based strategies, both compositional design and processing routes must be simplified. Metal additive manufacturing (AM), with its exceptionally rapid, non-equilibrium solidification, offers a unique platform to produce tailored microstructures in simple alloys that deliver superior mechanical properties. In this study, we employ laser powder bed fusion (LPBF) to fabricate 1080 plain carbon steel, a binary alloy comprising only iron and carbon. Deviating from conventional process optimization focusing primarily on density, we optimize LPBF parameters for mechanical performance. We systematically varied key parameters (laser power and scan speed) to produce batches of tensile specimens, which were then evaluated on a high-throughput mechanical testing platform (HTP). Using response surface methodology (RSM), we developed predictive models correlating these parameters with yield strength (YS) and elongation. The RSM models identified optimal and suboptimal parameter sets. Specimens printed under the predicted optimal conditions achieved YS of 1543.5 MPa and elongation of 7.58%, closely matching RSM predictions (1595.3 MPa and 8.32%) with deviations of −3.25% and −8.89% for YS and elongation, respectively, thus validating model accuracy. Comprehensive microstructural characterization, including metallographic analysis and fracture surface examination, revealed the microstructural origins of performance differences and the underlying strengthening mechanisms. This methodology enables rapid evaluation and optimization of LPBF parameters for 1080 carbon steel and can be generalized as an efficient framework for robust LPBF process development. Full article

Tungsten and tungsten alloys are widely used in important industrial fields due to their high density, hardness, melting point, and corrosion resistance. However, machining often leaves processing marks on their surface, significantly affecting the surface quality of precision components in industrial applications. Electrolytic polishing offers high efficiency, low workpiece wear, and simple processing. In this study, an electrolytic polishing method is adopted and a novel trisodium phosphate–sodium hydroxide electrolytic polishing electrolyte is developed to study the effects of temperature, voltage, polishing time, and solution composition on the surface roughness of a tungsten–nickel–iron alloy. The optimal voltage, temperature, and polishing time are determined to be 15 V, 55 °C, and 35 s, respectively, when the concentrations of trisodium phosphate and sodium hydroxide are 100 g·L⁻¹ and 6 g·L⁻¹. In addition, glycerol is introduced into the electrolyte as an additive. The calculated LUMO value of glycerol is −5.90 eV and the HOMO value is 0.40 eV. Moreover, electron enrichment in the hydroxyl region of glycerol can form an adsorption layer on the surface of the tungsten alloy, inhibit the formation of micro-pits, balance ion diffusion, and thus promote the formation of a smooth surface. At 100 mL·L⁻¹ of glycerol, the roughness of the tungsten–nickel–iron alloy decreases significantly from 1.134 μm to 0.582 μm. The electrochemical polishing mechanism of the tungsten alloy in a trisodium phosphate electrolyte is further investigated and explained according to viscous film theory. This study demonstrates that the trisodium phosphate–sodium hydroxide–glycerol electrolyte is suitable for electropolishing tungsten–nickel–iron alloys. Overall, the results support the application of tungsten–nickel–iron alloy in the electronics, medical, and atomic energy industries. Full article

Superhydrophobic coatings possess distinct wettability characteristics and hold significant potential in metal corrosion protection and underwater drag reduction. However, their practical application is often hindered by poor durability arising from the fragility of their micro/nanostructured surface roughness. In this study, a durable superhydrophobic coating featuring a hierarchical, hydrangea-like micro/nanostructure was successfully fabricated on an aluminum alloy substrate via a simple one-step cold-spraying technique. The coating consisted of hydrangea-shaped SiO₂ nanoparticles modified with 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDT) to produce multiscale roughness, while epoxy resin (EP) served as the binding matrix to enhance mechanical integrity. The hydrangea-like SiO₂ nanostructures were characterized by solid cores and wrinkled, petal-like outgrowths. This unique morphology not only increased the surface roughness but also provided more active sites for air entrapment, thereby enhancing the coating’s overall performance. The h-SiO₂@PFDT-EP composite coating exhibited excellent superhydrophobicity, with a WCA of 170.1° ± 0.8° and a SA of 2.7° ± 0.5°. Durability was evaluated through sandpaper abrasion, tape peeling, acid and alkali immersion, artificial weathering, and salt spray tests. The results demonstrated that the coating retained stable superhydrophobic performance under various environmental stresses. Compared with bare 6061 aluminum and EP coatings, its corrosion current density was reduced by four and three orders of magnitude, respectively. Furthermore, the coating achieved a maximum drag-reduction rate of 31.01% within a velocity range of 1.31–7.86 m/s. The coating also displayed excellent self-cleaning properties. Owing to its outstanding durability, corrosion resistance, and drag-reducing capability, this one-step fabricated superhydrophobic coating showed great promise for applications in marine engineering and defense. Full article

Metallic magnetic materials are extensively used to mitigate electromagnetic interference due to their high Curie temperatures and permeability. However, their high permittivity often hinders impedance-matching effectiveness, limiting their utility. In this study, amorphous cobalt–iron (Co_100−xFe_x) alloy nanoparticles with relatively low permittivity were synthesized using a simple aqueous reduction method at room temperature. The effect of atomic ratio variation on the microwave absorption properties of these nanoparticles was investigated across 2–18 GHz. The amorphous Co_100−xFe_x nanoparticles exhibited excellent electromagnetic wave absorption performance, achieving an effective absorption bandwidth of 5.6 GHz, a matching thickness of 2.60 mm, and a reflection loss of −42 dB. Full article

With the continuous consumption of fossil energy and the related environmental problems, clean energy, especially the hydrogen energy-derived water electrolysis, has attracted wide attention. However, as a result of the high energy consumption of water electrolysis and the limitations of single-function catalysts, there is an urgent need for cheap and simple-to-make bifunctional catalysts. In this work, based on the NiFe-LDH that is usually used for OER (Oxygen Evolution Reaction), doping of heteroatoms was carried out and a bifunctional catalyst could be then prepared using biomass as the carbon source. The preparation of catalyst precursors and in situ reduction were performed through the coupling process of hydrothermal and pyrolysis to enhance the electrolytic activity of the catalyst. Results showed that the overpotentials required to reach a current density of 10 mA·cm⁻² for the HER and OER processes were 305.2 mV and 310.4 mV, respectively, which are superior to the commercial catalysts. In the subsequent characterization, the structural characteristics of the catalyst support and their structure–activity correlation with active metals were systematically investigated by TEM, XRD, and XPS analysis, providing mechanistic insights into the catalytic behavior. The basic catalytic mechanisms of HER and OER were also obtained: the HER process was due to the formation of a Ni₃Fe alloy structure during catalyst preparation, which changed the electronic structure of the catalyst, while the OER process was induced by the formation of a NiOOH intermediate. The research results are expected to provide new ideas and data support for the preparation of bifunctional catalysts. Full article

Cr alloyed Cu exhibits puzzlingly high electrical conductivity compared with other 3d elements alloying. Here, we present a theoretical understanding based on standard electronic band structure calculations. The influence of local spin-polarization on electrical conductivity was first investigated. It is found that the non-magnetic calculation produces a high density of states peak at the Fermi level, and then it fails to explain the high electrical conductivity of Cu-Cr alloy. When spin polarization is taken into account, the density of states is significantly reduced, and the results are in good agreement with experimental measurements. Meanwhile, the calculation results can explain the increase in strength and also lead to some interesting deductions. Finally, a computational program is proposed to select a high electrical conductivity Cu alloy based on a simple calculation model. Full article

Magnesium alloys are widely used in all kinds of fields because of their excellent mechanical properties, but their application has been prevented by poor corrosion resistance. In this paper, Mg(OH)₂-Ca(OH)₂/Al(OH)₃/Al₂O₃ composite coatings with long-term corrosion resistance were fabricated on the surface of Mg alloys using the hydrothermal method. Among them, the calcium hydroxide/calcium nitrate–alumina coating successfully filled the cracks in the magnesium hydroxide coating. Meanwhile, we explored the influences of different heating times and temperatures on the coating and analyzed its composition. After immersing the coating in a 3.5% NaCl solution for 168 h, only a small portion of the surface dissolved. Electrochemical test results indicated that the corrosion potential and corrosion current density of the coating increased by three orders of magnitude, significantly improving corrosion resistance in comparison to bare samples. Adhesion tests showed that the coating exhibited good bonding performance to the substrate. This method features a simple, pollution-free preparation process and does not require complex instrumentation, thereby enhancing the longevity of the magnesium alloy. Full article

This work reports on the effect of the heavy rare earth element Er on Nd–Fe–B magnets by using a simple Er₆₉Fe₃₁ alloy additive, which is much less expensive than Dy and Tb elements. It was found that the corrosion resistance was improved with a minimal reduction in magnetic properties by rationally controlling the Er₆₉Fe₃₁ addition content. The main reason is that Er element partially replaces the Nd element at the edge of the main phase grain to form an (Er,Nd)₂Fe₁₄B shell with low H_A, which leads to a decrease in coercivity. However, the improvement in the corrosion resistance is mainly due to the Er₆₉Fe₃₁ alloy addition, which slows down the corrosion rate. Simultaneously, an investigation was conducted into the different advantages that target magnets when subjected to diverse heat treatment methodologies. The above findings may lead to the development of applications for other rare earth elements, thereby accelerating the development of low-cost permanent magnets comparable to commercially available sintered Nd-Fe-B magnets. Full article

Thermal spraying technique has potential in manufacturing economic, profitable thermoelectric coatings. In order to characterize the electrical performance of thermoelectric coatings more conveniently, a simple setup for thermoelectric power factor of thermoelectric coatings is designed and developed. The indigenously designed setup is simple and low-cost. The compact structure makes it easy to cooperate with existing heating furnace, allowing a fast measurement in a variable temperature range. The differential method and the off-axis four-point geometry are used in Seebeck coefficient and electrical resistivity measurement, respectively. The Spring-load unit and other details of construction of the setup are described specifically. The Seebeck coefficient of the plasma-sprayed higher manganese silicide (HMS) coating was measured to be approximately 132.35 μV/K at 150 °C, with measurements showing high linearity (R² > 0.99). The setup demonstrated reliable electrical resistivity results for Cr20Ni80 alloy, closely matching published values (1.16 × 10⁻⁶ Ω·m vs. 1.10 × 10⁻⁶ Ω·m). HMS coating was also characterized from 50 °C to 500 °C to validate the setup on thermoelectric performance characterization across a wide temperature range. These results confirm the reliability of the developed setup. Full article

As a kind of clean energy, hydrogen energy has great potential to reduce environmental pollution and provide efficient energy conversion, and the key to its efficient utilization is to develop safe, economical and portable hydrogen storage technology. At present, hydrogen storage technology lags behind hydrogen production and use, which is the bottleneck restricting the development of hydrogen energy. In this paper, several current solid-state hydrogen storage methods are reviewed, including hydrate hydrogen storage, alloy hydrogen storage and MOF hydrogen storage. At the hydrogen storage density level, the hydrogen storage capacity of 1K-MOF-5 can reach 4.23 wt% at 77 K and 10 MPa, and remains basically unchanged in 20 isothermal adsorption and desorption experiments. At the level of temperature and pressure of hydrogen storage, the alloy can realize hydrogen storage under ambient conditions. At the economic level, the cost of hydrogen storage in hydrates is only USD 5–8 per kilogram, with almost zero carbon emissions. Through the analysis, it can be seen that the above solid-state hydrogen storage technologies have their own advantages. Although hydrate hydrogen storage is lower than alloy materials and MOF materials in hydrogen storage density, it still has huge potential for utilization space because of its low cost and simple preparation methods. This paper further provides a comprehensive review of the existing challenges in hydrate research and outlines prospective directions for the advancement of hydrogen storage technologies. Full article

High-entropy alloys (HEAs) represent a paradigm-shifting material system offering vast compositional space for tailoring mechanical properties. The yield strength and hardness are critical performance metrics, yet their interrelationships in diverse HEAs remain incompletely understood, partly due to data limitations. This work employs an integrated machine learning framework to investigate the compressive yield strength (σ_y) and hardness (HV) correlation across a dataset of cast HEAs. Random forest models are successfully developed for phase structure classification (accuracy = 92%), hardness prediction (test R² = 0.90), and yield strength prediction (test R² = 0.91), enabling data imputation to expand the analysis dataset. Correlation analysis on the expanded dataset reveals a general positive trend between σ_y and HV (overall Pearson r = 0.75) but highlights a strong dependence on the predicted phase structure. The single-phase BCC alloys exhibit the strongest linear correlation between σ_y and HV (r = 0.88), whereas the single-phase FCC alloys show a weaker linear dependence (r = 0.59), and multiphase alloy systems display varied behavior. The specific ranges of compositional parameters (highly negative mixing enthalpy ΔH, low atomic size difference δ, high mixing entropy ΔS, and intermediate-to-high valence electron concentration VEC) are associated with a stronger σ_y-HV correlation, potentially linked to the formation of stable solid solutions. Furthermore, artificial neural network modeling confirms the varying complexity of the σ_y-HV relationship across different phases, outperforming simple models for some multiphase systems. This work provides robust predictive models for HEA properties and advances the fundamental understanding of the composition- and phase-dependent coupling between yield strength and hardness, aiding rational HEA design. Full article

Scaling up the production of TiAl turbine wheels for passenger car turbochargers requires the fabrication of thin blades that are similar to those of nickel-based superalloys. To achieve this, the molten metal fillability and impact resistance of thin blades must be improved. In this study, the effects of composition on these properties are predicted using simple laboratory experiments with binary, ternary, and practical alloys and are then verified with actual turbine wheels. The melt fillability of the turbine wheel blade is predicted using the amount of molten metal passing through an Al₂O₃-1%SiO₂ mesh. The binary alloy exhibits the best fillability, which is reduced by the addition of Cr and Si. Charpy impact tests on as-cast materials at 25 and 850 °C show that the addition of Cr and Mn improves the impact resistance, but the addition of Nb, W, Mo and Si reduces it. Therefore, the molten metal fillability and/or impact resistance of practical TiAl alloys containing such additives owing to other requirements are low and require improvement for use in thin-blade turbine wheel applications. Full article

Nickel–phosphorus (NiP) alloys have been widely used in many engineering fields such as aerospace, automotive, and optics; however, it is difficult to study the material removal mechanism and microscopic size changes in the polishing process of nickel–phosphorus alloys through simple experiments. In light of these difficulties, there is a need to improve our understanding of the surface friction and wear mechanisms of NiP materials. In the present study, molecular dynamics simulations are employed for the first time to investigate the material removal mechanism, mechanical response, phase transformation, and stress distribution of two NiP alloys with different phosphorus contents during the nano-polishing process by adjusting the polishing depth and speed. Our simulation results indicate that the mechanical response of the low-phosphorus alloy is slightly higher than that of the high-phosphorus NiP alloy. Larger polishing depths and higher speeds reduce the surface quality and lead to increased residual stress. The findings presented herein provide an atomic-level understanding of the material removal mechanism of NiP alloys via MD methodology and offer valuable guidance for selecting alloys with an appropriate NiP ratio as engineering materials and for developing processing methods to improve surface quality. Full article

The existing Al-Ce heat-resistant alloys are not extensively utilized in high-temperature applications due to their poor room-temperature mechanical properties. In this study, the Al-10Ce-3Mg-5Zn alloy was enhanced using hot extrusion and heat treatment. The as-extruded alloy exhibited bimodal intermetallic compounds and grain structures. Additionally, high-density microcracks and twins were observed in the micron-sized intermetallic compounds. Compared with the as-cast state, the as-extruded alloy demonstrated a higher ultimate tensile strength (UTS) of 317 MPa and better elongation of 11.0%. Numerous nano-sized T phases precipitated in the α-Al matrix after the heat treatment, contributing to a further rise in UTS (365 MPa). The high strength of the alloy is primarily due to its strong strain hardening capacity, fine grain strengthening, and precipitation strengthening effect. The change in elongation mainly results from the expansion of pre-existing microcracks, twin deformation, and microstructural refinement. The heat-treated alloys exhibited superior strength retention ratios at elevated temperatures (64% at 200 °C) compared to conventional heat-resistant aluminum alloys. The results of this paper indicate that hot extrusion and heat treatment are effective for developing heat-resistant Al-Ce alloys with high room-temperature strength, offering a simple process suitable for industrial production. Full article

Developing cost-effective and high-performance non-precious metal-based electrocatalysts for hydrogen evolution reaction is of crucial importance toward sustainable hydrogen energy systems. Herein, we prepare a novel hybrid electrode featuring intermetallic Fe₂Mo nanoparticles anchored on the hierarchical nanoporous copper skeleton as robust hydrogen evolution electrocatalyst by simple and scalable alloying and dealloying methods. By virtue of the highly active intermetallic Fe₂Mo nanoparticles and unique bicontinuous nanoporous copper skeleton facilitating ion/molecule transportation, nanoporous Fe₂Mo/Cu electrode shows excellent hydrogen evolution reaction electrocatalysis, with a low Tafel slope (~71 mV dec⁻¹) to realize ampere-level current density of 1 A cm⁻² at a low overpotential of ~200 mV in 1 M KOH electrolyte. Furthermore, nanoporous Fe₂Mo/Cu electrode exhibits long−term stability exceeding 400 h to maintain ~250 mA cm⁻² at an overpotential of 150 mV. Such outstanding electrocatalytic performance enables the nanoporous Fe₂Mo/Cu electrode to be an attractive hydrogen evolution reaction catalyst for water splitting in the hydrogen economy. Full article