Russian Journal of Non-Ferrous Metals最新文献

Aluminium–Magnesium (Al–Mg) alloys are widely used in light weight but high strength applications in various industries such as aerospace, automotive, etc. Also other improved properties are corrosion resistance and mechanical properties. This study explores the synthesis and characterization of Al–Mg alloys fabricated through the powder compositions, compaction under controlled pressure and sintering at optimized temperature to enhance densification and mechanical performance. The microstructural analysis, density measurement, hardness testing and conductivity are conducted to assess the influence of Mg content on the alloy properties. The results indicate that increasing Mg content enhances strength and microhardness due to solid solution strengthening and grain refinement, while also affecting the sintering behaviour.

Impurity reduction remains a critical challenge in aluminium recycling, particularly due to tramp elements such as Sn, Pb, Fe, Ni, and excess Si and Mg in Al–Si alloys used in automotive applications. This study presents a novel, sustainable refining flux synthesized from eggshell-derived calcium oxide (CaO), combined with NaCl, MgCl₂, Na₂B₄O₇, and Na₃AlF₆. The flux was comprehensively characterized using XRD, FTIR, SEM-EDS, and DSC-TGA, and applied to secondary Al–Si melts at 680  ±  20°C. Post-treatment analyses (ICP-MS and OES) demonstrated significant impurity reductions: Fe (22.5%), Si (19.5%), Mg (31.7%), and Zn, Pb, and Sn reduced by over 80%. The overall aluminium purity increased from 84.2 to 87.6 wt %. Dross analysis confirmed successful impurity segregation via slag formation, chlorination, and oxide capture. The results highlight the flux’s effectiveness in enhancing melt cleanliness while valorising bio-waste, providing a scalable, eco-friendly alternative to conventional fluxes in secondary aluminium recycling.

The rapid advancement in electronic and communication technologies has improved connectivity but increased electromagnetic wave pollution, posing health risks and disrupting systems. Lightweight, thin microwave-absorbing materials with broad frequency absorption are essential for mitigating electromagnetic interference. This review highlights advanced composites, magnetic alloys, and carbon-based materials like carbonized melamine foam (CMF), a porous structure promising for dielectric absorption, though limited by high conductivity. Combining CMF with insulating layers and magnetic coatings such as FeNi and SiO₂ enhances absorption by optimizing impedance matching. Magnetic alloys and dielectric coatings applied via magnetron sputtering improve absorption by balancing permeability and permittivity, critical for high efficiency in the X- and Ku-bands. The study explores FeCo-coated carbon nanofibers and SiC fibers, revealing how microstructural properties influence performance. This comprehensive analysis aids the design of stable, efficient electromagnetic absorbers for broad-spectrum applications.

Aluminum-based particulate composites, particularly those with nanoparticle reinforcements, are widely studied and utilized across various fields. The current study compares the mechanical and wear behavior of nanoparticle-reinforced Al7075 composites with predictions from an Artificial Neural Network (ANN) model. Two lots of composites were fabricated, reinforcing 0.6, 1.2, and 1.8 wt % of nano-sized Silicon Carbide (SiC) and Cenosphere (CS) by ultrasonic cavitation-assisted stir casting. The microstructure, dispersion of reinforcements, and wear surfaces were captured using a Scanning Electron Microscope (SEM). During the mechanical behaviour study, tensile, compression, and hardness tests were performed. The mechanical responses of the nano-reinforcements were theoretically calculated considering various strengthening mechanisms. The sliding wear study used three input factors–speed, distance, and load–each at three levels. SEM images confirmed uniform reinforcement dispersion. Cenosphere reinforcements had a greater impact on mechanical behavior than SiC. Cenosphere reinforcements significantly enhanced the mechanical behavior compared to SiC. Experimental yield strength exceeded theoretical values, with load transfer being the dominant strengthening mechanism, followed by dislocation strengthening. Al7075/Cenosphere composites exhibit a 71.9% lower wear rate, while Al7075/SiC shows a 45.93% lower wear rate compared to the pure Al7075 alloy. An ANN regression wear model was found to be 90.01% accurate compared to the experimental results.

Spent nickel–metal hydride (Ni–MH) batteries have attracted significant interest due to their high content of valuable metals. In this study, we propose an environmentally friendly thiosulfate leaching system that uses sodium thiosulfate (Na₂S₂O₃) and copper sulfate (CuSO₄) in combination to efficiently extract nickel (Ni), cobalt (Co), and rare earth metals (RE) from the electrode materials of spent Ni–MH batteries. Under the catalytic oxidation effect of Cu²⁺, the efficient and synergistic effective leaching of these valuable metals has been achieved. The experimental results indicate that the leaching efficiencies of Ni, Co, and RE reached 92.53, 95.91, and 98.95%, respectively. Kinetic analysis revealed that the leaching process of Ni was controlled by chemical reactions, whereas the leaching of Co and RE was governed by a mixed control. Moreover, we demonstrate a “waste-to-wealth” strategy by repurposing the sulfur-rich leaching residue as an effective photo-Fenton catalyst, achieving degradation efficiencies of 92.52% for Rhodamine B (RhB) and 70.58% for Methyl Orange (MO). This work provides not only an efficient alternative to traditional hydrometallurgical methods but also new insights into reaction kinetics and closed-loop material flows for sustainable battery recycling.

Aiming to develop high-strength Al–Cu–Mg alloys tailored for aerospace applications, this study investigates the influence of trace Sb addition on the microstructural evolution and mechanical behavior of Al–Cu–Mg alloys. This study employs scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize the effect of trace Sb addition on the microstructure of Al–Cu–Mg alloys. This study further explores property variations through hardness testing, tensile testing, and friction-wear characterization. Results demonstrate that trace Sb incorporation promotes the precipitation of θ' phase (Al₂Cu) in Al–Cu–Mg alloys, mediating a synergistic effect on microstructural refinement and mechanical property enhancement. Following solid solution treatment at 500°C for 1 h and subsequent aging treatment at 200°C for 4 h, the θ' phase in the matrix of the Al–4.5Cu–0.6Mg–0.2Sb (wt %) alloy exhibits a uniform distribution with small particle sizes, leading to enhanced alloy properties. The enhancement of the mechanical properties of the alloy is primarily attributed to the Sb element’s ability to facilitate the fine and uniform precipitation of additional θ' phases. After undergoing solution treatment at 500°C for 1 h followed by aging at 200°C for 4 h, the Sb-modified Al–Cu–Mg alloy demonstrates outstanding mechanical properties. Specifically, the alloy achieves a hardness of 128.2 HV, a tensile strength of 410 MPa, a yield strength of 345 MPa, and an elongation of 8.2%.

The microstructural features and mechanical behavior of a Co₄₀Cr₁₂Nb₂Mn₆Ni₄₀ medium-entropy alloy fabricated by vacuum-induction melting were studied. The microstructural studies by optical and scanning electron microscopies revealed the formation of a dendritic architecture with a dendrite size of 150–250 µm. Energy-dispersive spectroscopy confirmed a uniform Co/Ni ratio of ≈1 : 1 in the matrix and the homogeneous distribution of chromium and manganese throughout the sample volume. The presence of fine Nb-rich intermetallic particles with a niobium content of up to 6 at %, which provide dispersion strengthening of the material, was established. A comprehensive study of the mechanical behavior was carried out by instrumental indentation under loads ranging from 15 to 1000 mN and by uniaxial tensile tests. Nanoindentation revealed a pronounced dependence of hardness and elastic modulus on the applied load: the hardness decreased from 3.21 ± 0.61 GPa to 1.18 ± 0.6 GPa and the elastic modulus decreased from 131.7 ± 44.1 to 44.7 ± 1.4 GPa. The ultimate tensile strength was 486 MPa, with a high elongation to failure of 92.6%. The specimens were found to exhibit a mixed-mode fracture characterized chiefly by a ductile dimpled mechanism of fracture with the presence of isolated regions of transcrystalline cleavage. The size of dimples varied from 3 to 20 µm, with large dimples (10–20 µm) constituting approximately 20% of the total count. Spherical inclusions of up to 5 µm in size, which served as micropore nucleation sites, were detected at the bottom of the large dimples.

This work is dedicated to the analysis of the influence of the core material on the complex of physical and mechanical properties of copper-clad aluminum wires (CCAW) in hard (hard-drawn) and soft (annealed) states. Low-alloyed aluminium alloys of the Al–Fe system were chosen as research material as an alternative to the conventionally used technically pure aluminium in terms of thermal stability, mechanical strength and ductility. Such alloys, while still retaining low cost and high electrical conductivity, are characterized by the improved relative to technically pure Al mechanical strength and thermal stability. Alloys used in this study were produced by casting into electromagnetic mold to further improve their mechanical properties. Three different alloy compositions Al–0.5 wt % Fe, Al–0.5 wt % Fe–0.3 wt % Cu and Al–1.7 wt % Fe were used. To achieve a hard-drawn state, the copper-clad wire was cold-drawn to a reduction degree of 90%, and the soft state was achieved by annealing at 300 and 325°C for 1 h. To compare CCAW with the core materials produced by electromagnetic casting, samples with similar copper content were produced based on commercial alloy 8176, produced by a traditional combined casting and rolling method. Based on the experimental data obtained and the results of the optimization performed (from the combined tensile strength, ductility and electrical conductivity point of view) using the linear convolution target function, the most suitable alloy of the Al–Fe system as the core material for the CCAW was proposed.

The effects of four processing parameters related to the mixing equipment of controlled diffusion solidification (CDS) with simultaneous mixing on the Al–8Si casting microstructure were first investigated by orthogonal test method, taking pure Al and Al–12Si as precursor alloy 1 and precursor alloy 2 respectively. The result indicated that the influence degree decreased in the sequence of mixing crucible diameter, pouring height, mixing rate and pouring distance, due to the reduced variation magnitudes of flow field and vorticity field intensities in the mixed melt revealed by using subsequent one-factor variation method. Specially, a set of optimal parameters was obtained, at which a better mixing effect was achieved than those from all the previous investigations. The final experiment showed that the resulted CDS casting had a quite ideal nondendritic microstructure with primary grain size of 38.56 μm and shape factor of 1.28. More importantly, the casting had good tensile properties, and the yield strength, ultimate tensile strength and fracture elongation were 18.9, 28.6 and 165.5% higher than those of the traditional casting counterpart, respectively, attributing to the significant decrease and even elimination of shrinkage porosities, as well as the refinement of eutectic Si phases.

The study examines the configuration entropy influence on the work output in the Ti–Hf–Zr–Ni–Cu–Co shape memory alloys and compare the results to those found in the binary NiTi alloy. The samples were pre-deformed at –196°C by 10%, unloaded, fixed to the bias elastic element and subjected to heating–cooling–heating with a system stiffness of 22 GPa. It was found that an increase in the concentration of doping elements (Hf, Zr, Cu, Co) led to non-monotonic variations in recoverable strain, recovery stress and work output. The maximum values were observed in the medium entropy alloys in which the work output was twice larger than in low-entropy Ti–Hf–Zr–Ni–Cu–Co alloys or in binary NiTi alloy. High-entropy alloys produced less work compared to the medium-entropy alloys due to a smaller volume fraction of the oriented martensite after pre-deformation as these materials demonstrate the superelasticity even at –196°C.