Russian Journal of Non-Ferrous Metals最新文献

This study systematically investigates the effects of Zr content (0–0.3 wt %) on the microstructure and mechanical properties of cast-rolled Al–Mg–Si–0.4Mn aluminum alloys. Four types of sheets with different Zr contents were prepared using a horizontal twin-roll continuous casting and rolling process, and a multi-stage homogenization annealing process of 350°C/2 h + 400°C/1 h + 300°C/6 h was established. The grain morphology, texture evolution, second-phase distribution, and mechanical properties of the sheets after homogenization were characterized. The results indicate that the addition of an appropriate amount of Zr (0.2 wt %) significantly suppresses recrystallization, increasing the proportion of small-angle grain boundaries to 79.9% and refining the average grain size to 43 μm. At the same time, it promotes the transformation of coarse β-Fe phase into rounded α-Fe phase; compared to the case without Zr addition, the volume fraction of the iron-rich phase decreased by 69.34%. At this composition, the sheet’s yield strength, tensile strength, and elongation reached 126, 176 MPa, and 16.8%, respectively, representing increases of 21.7, 22.5, and 34.1% compared to the sheet without Zr addition. Excessive Zr addition (0.3 wt %) led to coarsening of the primary Al₃Zr phase, inducing abnormal grain growth, with the recrystallization fraction rising to 32.09% and mechanical properties significantly decreasing. Fracture analysis showed that the cast-rolled sheet containing 0.2 wt % Zr exhibited the most uniform, dense, and deep dimples with distinct tear ridges, indicating the strongest plastic deformation capacity and the most thorough energy absorption.

The addition of nano scale ceramic reinforcements into lightweight metal matrices has gained a large attention towards the development of advanced structural materials. In this research, the AZ91D magnesium alloy matrix was reinforced with nano-CeO₂ particles to form a magnesium metal matrix composite that has enhanced mechanical and thermal properties. This fabricated composite is subjected to a Quantitative Phase analysis using X-Ray Diffraction (XRD) to identify and evaluate the crystalline phases and their relative volume fractions. Scanning Electron Microscopy (SEM) is used to describe the surface morphology of the reinforced matrix. The results show the formation of a highly crystalline Mg–CeO₂ composite with nanoscale reinforcement, stable interfacial bonding and absence of secondary phases, highlighting the potential of nano CeO₂ as an effective reinforcement for lightweight magnesium-based metal matrix composites.

The effects of rare earth Sc content and heat treatment on the microstructure, tensile properties, and corrosion resistance of the A356 aluminum alloy are investigated in this work. The effect of Sc on the alloy recrystallization was analyzed. Findings reveal that heat treatment refines the α-Al phase and modifies the deleterious coarse eutectic Si structure. The Si phases were transformed from long needle-like to short rod-like Notably, the optimal microstructure, tensile properties, and corrosion resistance of the alloy were obtained with the addition of 0.6 wt % Sc and subsequent solution treatment at 560°C. Results indicate that the A356 aluminum alloy, with the addition of 0.6 wt % Sc and subjected to heat treatment at 560°C, achieves the maximum values of yield strength (166 MPa), tensile strength (242 MPa) and ductility (elongation: 6.5%). Meanwhile, this alloy exhibits the lowest corrosion current density (138.93 μA cm^–2) and the most positive corrosion potential (–0.9197 V), indicating that the corrosion and mechanical properties of the Sc-modified A356 alloy are improved after heat treatment. The possible formation of V-AlSi₂Sc₂ (AlSc₂Si₂) is also addressed; no coarse V-phase was detected by XRD or SEM/EDS, although trace nanoscale V-phase cannot be excluded without TEM.

Cu–Pd and Cu–Pd–Ag alloys can find application as corrosion-resistant conductors of weak electrical signals. The work is devoted to the comparison of the structure and physical and mechanical properties of copper, Cu–8Pd and Cu–8Pd–3Ag alloys (at %). Samples in various initial states were studied: quenched and deformed, and annealed at temperatures ranging from 150 to 450°C. Heat treatment durations ranged from 0.5 to 216 h. It has been established that in almost the entire range of annealing temperatures, the electrical resistance of the ternary alloy is higher than that of the binary alloy. The most significant increase in electrical resistance of both the initially deformed and pre-hardened alloy Cu–8Pd–3Ag is observed after annealing for maximum duration at temperature of 250°C. X-ray diffraction patterns of samples after such heat treatment remain virtually unchanged.

This study investigates an efficient hydrometallurgical route for the recovery of Pb from spent Pb–acid battery paste using nitric acid leaching followed by carbonate precipitation. Effect of different inorganic and organic acid were investigated. It was observed that nitric acid exhibited highest recovery among other acids. Response Surface Methodology (RSM) was applied to optimize process based on a Box–Behnken design by evaluating the effects of acid concentration, particle size, and stirring time. A second-order polynomial model was developed, and analysis of variance confirmed the adequacy and significance of the model with a high coefficient of determination (R² = 0.9795). Particle Size was identified as the most influential parameter. Under optimized conditions such as acid concentration 3.8134 M, particle size 150 μm and stirring time 210 min, a maximum recovery of Pb, approximately 91.21% was achieved experimentally, showing good agreement with model predictions. Furthermore, kinetic analysis of the leaching process was conducted using the shrinking core model, revealing that the reaction is predominantly governed by diffusion through the porous product layer. This finding is supported by the relatively low activation energy value of 10.49 kJ/mol, confirming diffusion-controlled kinetics. Overall, the proposed process presents an environmentally friendly and efficient approach for the recovery of Pb from spent LABs.

In this paper, the effect of deformation by equal-channel angular pressing (ECAP) and subsequent coating formation using various regimes (pulsed unipolar polarization—PUP and pulsed bipolar polarization—PBP) of plasma electrolytic oxidation (PEO) on the corrosion behavior of a bioresorbable Mg–Zn–Zr magnesium alloy was studied. Structural studies, gravimetric and electrochemical corrosion tests were performed to evaluate the alloy’s resistance to corrosion in Ringer’s solution. It was found that the use of ECAP contributes to structure refinement and a decrease in the corrosion rate, as compared to the initial state, to 7.6 ± 0.7 mm/year. The best corrosion resistance of the alloy in both the initial and deformed states is ensured by applying the PEO coating using the PUP regime; the corrosion rate was 2.8 ± 0.2 and 3.8 ± 0.4 mm/year, respectively. This may be due to the fact that this regime exhibits a higher content of the high-temperature forsterite Mg₂SiO₄ phase_. Electrochemical tests indicate a decrease in the corrosion current density for the PEO-coated samples by 3–4 orders of magnitude. ECAP processing leads to an increase in the polarization resistance to corrosion for the samples with a PEO coating produced in the PUP and PBP regimes.

The main objective of this part of the research is to address the insufficient improvements in mechanical and tribological properties resulting from powder metallurgical (PM) fabrication processes for metal matrix composites derived from A356 aluminum alloy. The aim of this study was to investigate the impact of successive incorporation levels (0.5–3.5 wt %) on the properties of the A356 matrix, including density, hardness, and wear characteristics. A356 powder was reinforced with varying amounts of SiC and uniaxially pressed at 200 MPa, followed by mechanical milling while sintering in an argon atmosphere at a temperature of 586 C, characterized via physical/mechanical tests performed, as well as systematized pin-on-disk standardized wear tests. The outcome showed a significant property improvement where the bulk density of pure A356 alloy was 2.61 g/cm³, which increased to 2.67 g/cm³ at 3.5 wt % SiC. Highest hardness (82.4 HV) and the lowest wear rate of 1.8 × 10^–5 g/cm² at 3.5 wt % SiC. However, microstructural analysis indicated that 2.5 wt % SiC. The highest load of SiC at which homogeneity is retained, the following higher (3.5 wt %) induced particle aggregation locally, and its microporosity slightly increased. Our results support the hypothesis that SiC nanoparticles can reinforce A356 alloy to a large extent, with inclusions of 2.5–3.5 wt % providing superior mechanical and tribological properties.

This study delineates the development and thorough evaluation of AA3105 aluminum alloy composites fortified with carbonized eggshell powder, iron slag, and Nano-MgSO₄. To get even distribution, the reinforcement particles were ball-milled and then turned into a single entity before being added to the aluminum matrix using stir casting. To make the composites even better, precipitation hardening was used to improve their mechanical and functional qualities. Microstructural examination showed that the particle distribution was more uniform and refined, and that the particle-matrix interfacial bonding was strong. This made the load transfer better and the overall structural integrity better. Mechanical tests showed a big improvement in tensile strength and hardness. After heat treatment, the AA3105/7.5% CESA/7.5% Iron Slag/1.5% MgSO₄ composite’s tensile strength and hardness went up by about 36 and 65%, respectively. The presence of strong reinforcing phases made ductility and impact toughness go down a little bit, but heat treatment brought them back up by refining the grains and relieving stress. Corrosion testing in 3.5 wt % NaCl showed very little weight loss (around 0.009–0.010 g), and thermal expansion tests showed that the material was very stable in size (4.0–4.1 mm³), which shows that it is quite resistant to chemicals and heat. The findings underscore the synergistic effect of eggshell, iron slag, and Nano-MgSO₄, demonstrating that industrial and agricultural waste can be efficiently employed to create sustainable, high-performance aluminum matrix composites. The research confirms that these hybrid composites have superior mechanical, thermal, and corrosion characteristics, rendering them appropriate for structural and high-temperature engineering applications.

In the present work, an experimental methodology was developed to investigate the structure–property–processing relationships governing the influence of Zn addition (0.31, 0.82, 1.41, 2.05, and 2.54 wt %) in an as-cast Al–Si–Cu alloy, with particular focus on corrosion resistance, wear behavior, and thermal properties. Microstructure analysis was carried out using SEM, EDS. Comparative studies were performed through electrochemical tests in NaCl solution (stationary and non-stationary methods) and sliding wear tests using a ball-on-disc configuration at room temperature. The DSC method was chosen to comprehensively study the thermal behavior of cast Al–Si–Cu–Zn alloys. The results show Zn modifies the morphology of the Al₂Cu phases, influences solidification, and improves the properties of the α-Al matrix through partial dissolution. An optimal Zn content of around 0.82 wt % significantly enhances corrosion resistance by forming a stable protective film. Tribologically, small additions of Zn decrease the coefficient of friction and increase wear resistance via the formation of a protective tribofilm, while an excess of Zn excess Zn leads to instability, delamination, and increased wear. Thermal analysis reveals a threshold effect: low Zn contents maintain eutectic and thermal stability, while high contents induce unfavorable phase transformations. A Zn content of about 0.82 wt % was found to offer the best balance between microstructural stability, corrosion resistance, wear performance, and thermal behavior in the studied Al–6Si–3Cu alloy.

Limitations in the possibilities of using such interesting materials in terms of the ratio of density and volumetric mechanical characteristics as magnesium alloys with the addition of rare earth elements (Mg–RE), associated with the low corrosion properties of their surface, impose the need to search for and improve methods for its improvement. Of particular importance is the elimination of the phenomenon of microgalvanic corrosion that occurs at the interfaces between the phases of the alloy matrix (a-Mg) and secondary strengthening phases. The mechanical properties of the Mg–RE surface are also insufficient for work under contact conditions. In this research, the method of electrochemical formation of conversion protective ceramic layers—plasma electrolytic oxidation (PEO)—was modified by the addition of cerium dioxide particles CeO₂ into the electrolyte at two modes (medium (250 Hz) and high (1000 Hz)) of technological pulse frequencies. It has been established that the mechanism of incorporation of dispersed particles of cerium dioxide consists of both electrophoretic incorporation of particles into the forming coating and thermokinetic inert incorporation as a result of impact interaction of particles and the oxide layer, and in both cases, preservation of CeO₂ particles in its original state occurs. Modification of coatings with CeO₂ particles allowed increasing resistance to chipping by up to 50 times and reduce the chip area during indentation from ~0.5 up to ~0.01 mm², and the use of high-frequency PEO mode, in general, improves resistance to chipping by ~2–3 times, regardless of the concentration of CeO₂ particles in the electrolyte compared to the mid-frequency. The CeO₂ particles had greatest influence on the wear resistance of the oxide coating—high-frequency PEO with the addition of CeO₂ allowed reducing the values of specific wear to ~0.05–0.1 µm/(N m) at high frequency PEO versus with ~0.3 µm/(N m) for the base coating obtained in mid-frequency PEO. Without the addition of particles, high-frequency PEO allowed reducing the wear of the base coating in the experiment by ~1.5 times compared to the medium-frequency one, which indicates the synergy of the interaction of the CeO₂ additive and high-frequency PEO. Studies of the corrosion properties of coatings have shown that CeO₂ particles slightly reduced the original characteristics, however, with prolonged exposure to a corrosive medium, some restoration of the corrosion properties of the coatings and the formation of a new corrosion-resistant phase in them—Mg_0.667Al_0.333(OH)₂(CO₃)_0.167(H₂O)_0.5 (hydrotalcite)—is observed.