JOM最新文献

The development of lightweight, high-strength materials with superior mechanical and thermal properties is crucial for aerospace, automotive, and structural applications. This study investigates the thermomechanical and microstructural behavior of a novel AA8011-based hybrid composite reinforced with boron carbide (B₄C) and reduced graphene oxide (rGO). The composites were fabricated using a bottom-pour stir casting process, with reinforcement loadings varied from 3 wt.% to 9 wt.% B₄C and 2–6 wt.% rGO. Microstructural analysis using SEM, EDS, and TEM confirmed uniform dispersion of rGO and effective interfacial bonding with the matrix, while localized B₄C agglomeration was observed at higher loadings. Mechanical characterization revealed significant improvements: microhardness increased by 35%, tensile strength by 28% (210 MPa), flexural strength reached 497 MPa, and impact strength by 23% for the optimal composition containing 9 wt.% B₄C and 2 wt.% rGO. These enhancements are attributed to grain refinement, Orowan strengthening, and efficient load transfer mechanisms facilitated by the dual reinforcement system. The developed composites demonstrate strong potential for high-performance engineering applications where strength, stiffness, and durability are critical.

Mixed magneto-hematite is one of the most typical iron ores in China. The standard beneficiation process involves stage grinding, coarse and fine classification, gravity–weak magnetic–strong magnetic separation, and anionic reverse flotation. Here, to improve the sorting efficiency of this iron ore type, vibrating sample magnetometry is used to analyze the magnetization characteristics of various magnetite, hematite, and gangue minerals at different mixed ratios and grinding fineness levels. Moreover, a three-product magnetic separator is developed for sorting both magnetite and hematite. The three-product magnetic separator has a unique magnetic system structure designed to target strongly magnetic magnetite and weakly magnetic hematite respectively. The experimental results show that, when the feeding concentration is set to 50%, the cylinder rotation speed is 20 rpm, the cylinder angle is 5°, and the unloading pipe water pressure is 0.2 MPa, the concentrate and tailings exhibit grades of 44.63% and 10.17%, respectively, with a concentrate recovery rate of 72.14%. The separation of both magnetite and hematite particles in the three products magnetic separator is facilitated by different responses of ore particles to various forces, including magnetic force, centrifugal force, fluid traction, and other composite force fields.

Alternating magnetic field-assisted laser cladding is an effective method to reduce coating defects. However, it is difficult to fully reveal the influence of dynamic magnetic fields on the distribution of elements and the solidification structure merely through characterization experiments. Therefore, in this paper, a three-dimensional numerical model of alternating magnetic field-assisted laser cladding has been established. By analyzing the regulatory behavior of the Lorentz force on the molten pool, the influence of the alternating magnetic field on the mass transfer behavior and solidification characteristics was further revealed. The results show that the magnetic field varying at 50 Hz excites the Lorentz force varying at 100 Hz. Under the influence of the magnetic force, the diffusion ability of Cr element is enhanced. The change in concentration shows that the concentration of Fe element on the cladding layer increased from 84.5 wt.% at 0 mT to 86.3 wt.% at 90 mT. During the solidification stage, with the increase of the magnetic field intensity, the cooling rate increased from 7164 K/s to 8655 K/s, while morphological parameters decreased from 4.69 × 10⁸ s × K/m² to 3.12 × 10⁸ s × K/m². Under the alternating magnetic field, the cladding layer exhibits accelerated microstructural transformation and reduced crystal size.

During the use of cables, the external stress and irradiation damage the internal structure of the cable sheath, resulting in the deterioration of the insulation properties and mechanical properties of the material. Under the action of external stress, the cable sheath may produce micro-cracks and insulation deformation. Irradiation breaks the molecular chain of the cable material, causes cross-linking damage, and accelerates the decrease of the insulation characteristics and mechanical strength of the sheath. In this paper, the wide band gap semiconductor SiC is doped into XLPE, and the surface of SiC is treated with silane coupling agent to improve its dispersion. SiC has a wide band gap and the ability of surface defects to capture electrons, which slows the bombardment of carriers, enhances the electrical insulation characteristics of the material, and also greatly improves its resistance to radiation damage. The results show that, when the SiC content is 1.5 wt.%, the tensile strength and breakdown field strength of the composites are the largest, at 22.7 MPa and 28 KV/mm, respectively. At this time, compared with pure XLPE, the insulation characteristics and mechanical properties of 1.5 wt.% SiC/XLPE composites are less degraded under different irradiation doses. When the doping amount of SiC is 1.5 wt.%, the doping concentration is the best. At this concentration, the best anti-radiation value is 100 kGy. Through X-ray photoelectron spectroscopy (XP) analysis, this study reveals the mechanism of radiation aging resistance behind SiC-doped XLPE. In this study, wide band gap semiconductor silicon carbide was selected as the filler, and different content of silicon carbide was added to cross-linked polyethylene. Compared with the undoped control sample, the incorporation of silicon carbide significantly improves the insulation performance and tensile strength of the composite material. The effects of radiation on the insulation properties of cross-linked polyethylene before and after doping were investigated by measuring the breakdown strength, dielectric constant, dielectric loss, and volume resistivity of the composites at different radiation doses. The tensile strength and elongation at break of the material before and after doping at different radiation doses were measured to explore the effect of radiation on its mechanical properties. The change mechanism of dielectric properties of silicon carbide nanocomposites before and after irradiation is proposed by changing the mechanical properties, breakdown characteristics, dielectric constant, and loss of silicon carbide nanocomposites before and after irradiation. This study realizes the simultaneous enhancement of insulation and radiation resistance of cable materials, which is of great value for prolonging cable life.

To search for excellent Re-Zr ultrahigh-temperature alloys, the first-principles method has been used to study the structural, mechanical, and thermodynamic properties of five Re-Zr alloys. The results show that two novel cubic phases, ReZr and Re₃Zr, are predicted first. The convex hull indicates that Re₂Zr has better thermodynamic stability compared to the other Re-Zr alloys. It has been found that the elastic modulus of Re-Zr alloys increases with increasing Re concentration. In particular, these Re-Zr alloys show better ductility with a high elastic modulus. Naturally, the high elastic modulus is that the high-concentration Re enhances the localized hybridization between Re and Zr atoms, and between Re and Re atoms. Furthermore, the elastic modulus of Re₂₄Zr₅ is higher than that of the other four Re-Zr alloys. The high elastic modulus of Re₂₄Zr₅ is related to its octagonal Re-Re cage structure, which is composed of four Re-Re bonds. Finally, it has been found that the thermodynamic properties of Re₂₄Zr₅ are better than that of the other Re-Zr alloys.

This study investigates the development and optimization of chitosan-stabilized titanium-based lithium-ion sieves (Ti-CH LIS) for lithium extraction from aqueous media. A solid-state reaction method was employed, with calcination temperature and chitosan-to-gelatin ratio optimized using response surface methodology (RSM). Analytical techniques, including XRD, SEM, FTIR, ICP, and PSA, confirmed the successful formation of highly crystalline Li2TiO3 with improved porosity and particle dispersion resulting from the incorporation of chitosan. The optimal material, synthesized at 850°C with a 1:1 chitosan-to-gelatin ratio, achieved a lithium adsorption capacity of 64.04 mg/g within 24 h, only slightly lower than the 68.08 mg/g observed in unmodified LIS. Despite the minor reduction in capacity, chitosan significantly improved adsorption kinetics and minimized particle agglomeration. Stability tests showed that Ti-CH LIS maintained over 92% of its adsorption capacity after ten cycles, with titanium leaching below 1.3%, indicating superior durability compared to the unmodified counterpart. Statistical analysis confirmed calcination temperature as the most critical factor influencing performance. Overall, Ti-CH LIS demonstrates great potential as a robust and efficient adsorbent for lithium recovery in complex aqueous systems, particularly geothermal brines.

The existence of a particle oxide layer affects the mass distribution, thermophysical properties, and surface characteristics of particles, so it is necessary to carry out detailed parametric description of the physical and chemical properties of oxidized spray particles. Therefore, based on the oxidation parameters of spray particles obtained from the spray flow field, oxidized sprayed particles were introduced into the particle deposition mode. At the same time, considering the particle oxidation degree, substrate roughness, and grain heterogeneity of stainless-steel substrates, a 3D supersonic thermal (HVOF) spray process multiphase particle sputtering deposition microcrystal model was established. The sputtering deposition behavior of an oxidized particle flow and of a non-oxidized particle flow were compared and analyzed, and the transient evolution law of the temperature field, strain field, and stress field caused by sputtering deposition of sprayed particles was revealed. The results show that the oxide layer impedes the heat transfer and the local stress concentration effect caused by brittleness. It was shown that the temperature, velocity, and stress of the coating deposited by oxidized particles are higher than that without considering oxidation. The temperature was 1700 K, the stress was 1109 Mpa and the strain was 16.7, resulting in a 1.73% higher porosity than that without considering oxidation.

Energy conservation and emission reduction is a crucial issue. Aluminum/steel composite structural components can save energy by utilizing the beneficial properties of dissimilar metals, meeting product requirements while reducing weight. Friction stir welding (FSW) is one of the most promising techniques for joining dissimilar materials. This paper focuses on 5083 aluminum alloy and Q235 steel. Using the coupled Euler-Lagrange method, a finite element model of butt FSW for these two materials under positively biased tool conditions is established. Then, considering the simulation results and actual welding equipment conditions, the one-factor test method is employed to design butt friction stir welding experiments for three welding parameters: offset, welding speed, and rotational speed. The mechanical properties, microstructure, and morphology of the joints produced with various weld parameters were also investigated experimentally. Numerical analysis indicates that the optimal welding parameters for 5083 aluminum alloy and Q235 steel are a welding speed of 55 mm/min, a rotational speed of 400 r/min, and an offset of 0.7 mm. Twelve groups of welding parameter combinations are designed based on existing conditions. Experiments show that all three parameters affect weld formation via heat input. Offset influences the distribution of steel fragments in the weld channel, while welding speed affects weld surface flatness.

To investigate the influence of temperature on the interfacial phase transformation between hexagonal close-packed (HCP) and face-centered cubic (FCC) structures during ball milling, molecular dynamics simulations were conducted to study the atomic-scale evolution of pure titanium. Changes in the crystal structure and dislocation evolution were observed. The effects of ball milling at different temperatures ranging from 300 to 1200 K on titanium's mechanical properties, crystal structure, and dislocation evolution were analyzed. The study revealed that some Shockley partial dislocations are associated with FCC stacking faults. Moreover, due to the synergistic effects of frictional shear and thermal activation, a unique core–shell structure was formed, where an outer shell enriched with FCC and body-centered cubic (BCC) structures encapsulates an HCP core. This suggests the presence of a non-equilibrium transformation pathway facilitated by interfacial dislocation activity and defect migration. This work provides insights into the solid-state phase transformation of titanium, offering theoretical guidance for designing thermally stable, wear-resistant materials in powder metallurgy and tribological applications.

This study centered on the recovery of Sb, Pb, and Au from the synergistic smelting of antimony-gold concentrate and lead concentrate. The predominance area diagram of the Pb-Sb-S-O system and phase-equilibrium distributions of key smelting reactions were calculated and visualized using FactSage. Considering the compositional features of the raw materials, the FeO-SiO₂-CaO-ZnO-Fe₃O₄-PbO slag system was selected for in-depth exploration. The impacts of the CaO/SiO₂ (mass ratio), Fe/SiO₂ (mass ratio), ZnO content, and temperature on the liquidus temperature and slag viscosity were determined. Theoretical calculations revealed that an increase in the Fe/SiO₂ ratio results in a rise in the slag liquidus temperature. Significantly, when the CaO/SiO₂ ratio reaches 0.5, the liquidus temperature attains its maximum value. Additionally, at temperatures above 1150°C, the slag viscosity remains below 0.5 Pa s. Verification experiments showed that, in the alloy phase, the Pb content is 73.81%, the Sb content is 20.17%, and the Au content is 103.44 g/t. Moreover, the combined direct recovery rate of Pb and Sb in the alloy is 45.70%, and the total grade of Pb and Sb in the alloy can reach up to 93.98%.