Russian Journal of Non-Ferrous Metals最新文献

The CNT–Al composite wires were prepared by a novel method of direct addition of carbon nanotubes to aluminum molten steel, rather than conventional powder metallurgy and in situ synthesis. The effects of carbon nanotubes on the microstructure and mechanical properties of CNT–Al composites and the dispersion properties of carbon nanotubes were investigated. The improved microstructure and mechanical properties of the composites were attributed to the enhancement of carbon nanotubes on the aluminum matrix. When the content of carbon nanotubes is 0.3%, the particle size of CNT–Al composite is 15–25 μm. At that time, mechanical properties of CNT–Al composite are as follows. The tensile strength was 250 MPa, elongation was 4.5%, hardness was HB 80 and bending number was 5.5 times. The simulation of the dispersion of CNTs showed the best dispersion of CNTs with inert gas (N₂) and directly dispersed in molten steel.

The Mg–Zn–Y alloy having (leftlangle {11bar {2}0} rightrangle ) oriented columnar crystals was prepared by directional solidification, and its microstructure and tensile properties were investigated. Furthermore, the relationship between twins and strain field evolution during tensile deformation was investigated by Scanning Electron Microscope-Digital Image Correlation Method (SEM-DIC). With increasing tensile strain, (left{ {10bar {1}1} right}) contraction twins and (left{ {10bar {1}1} right})–(left{ {10bar {1}2} right})double twins are activated. These contraction twins can transmit across grain boundaries to form adjoining twin pairs (ATPs). SEM-DIC data shows that the formation of ATPs can effectively coordinate strain on both sides of grain boundaries. Therefore, the elongation of the alloy is as high as 42% at room temperature.

The Chaabet El Hamra deposit in northeastern Algeria represents a promising but mineralogically complex zinc resource. This study investigates the optimization of flotation parameters to enhance zinc recovery and concentrate quality. Detailed mineralogical and granulometric analyses revealed that sphalerite was the primary zinc-bearing mineral, finely disseminated within a gangue matrix dominated by quartz and dolomite. Experimental grinding tests indicated that milling for 42–45 min achieved optimal liberation at 74 µm, a critical threshold for effective flotation. Flotation trials were performed under varying conditions of copper sulfate activation, amyl xanthate dosage, and froth scraping times. The highest zinc recovery (86.31%) and concentrate grade (49.05%) were obtained at a collector dosage of 150 g/t, an activator dosage of 200 g/t, and a 7-min scraping duration. Kinetic modeling using both first-order and Kelsall’s two-component models confirmed the flotation system’s efficiency and highlighted the coexistence of fast- and slow-floating mineral fractions. Response surface methodology (RSM) further elucidated the nonlinear interaction between reagents, defining an optimal operating window. The study provides a comprehensive framework for industrial flotation optimization and demonstrates the value of integrating kinetic modeling with mineralogical characterization. These findings contribute to improving the economic and environmental performance of zinc beneficiation in polymetallic ore contexts. The optimum flotation conditions (pH 9, 500 g/t collector dosage, and 10 min conditioning time) provide a robust basis for upscaling the process to industrial scale.

This study investigates the leaching behavior of three rare earth elements (REEs), cerium (Ce), lanthanum (La), and neodymium (Nd) from apatite concentrate derived from iron ore waste using hydrochloric acid. The effects of key parameters, including acid concentration, solid-to-liquid (S/L) ratio, leaching time, and temperature, were systematically evaluated using response surface methodology (RSM). Statistical analysis revealed that acid concentration and temperature had the most significant influence on REE extraction, whereas leaching time had a comparatively minor effect. Under optimized conditions (37% HCl, 1 : 9 S/L ratio, 60 min, and 65°C), maximum recoveries were achieved: 94.19% for Ce, 86.33% for La, and 76.34% for Nd. These findings confirm the viability of hydrochloric acid leaching as an effective technique for REE extraction from apatite-rich waste. Moreover, the optimization process provides a cost-effective approach, striking a balance between high recovery efficiency and moderate chemical and energy inputs.

The applicability of organophosphorus extractants (D2EHPA, P-507, and Cyanex 272) for the selective separation of Mn, Co, Ni, and Li from the succinic acid leach liquor of cathode material of spent lithium-ion batteries (LIBs) was investigated. Extractant P-507 exhibited superior selectivity in separating Mn from Ni and Li, with separation factors of βMn/Ni = 145.2 and βMn/Li = 130.0, surpassing D2EHPA (71.0 and 70.5). Slope analysis and infrared spectroscopy indicated that Mn extraction by P-507 proceeds via a cation exchange mechanism, while succinic acid acts as a buffer and stabilizes the equilibrium pH. Optimization of process parameters revealed that the concentration of P-507 in the diluent affects Mn recovery and its separation from Ni and Li, whereas temperature and contact time have negligible effects. Scrubbing of the loaded organic phase with 6 g L^–1 MnSO₄ removed 60% of Co and 98% of Ni/Li. Mn stripping exceeding 97% was achieved in a single stage using 50 g L^–1 H₂SO₄ at an O : A ratio of 2 : 1. These results confirm the potential of P-507 for the development of sustainable metal recovery technology from secondary sources.

Rare earth elements (REEs) are indispensable to clean energy and advanced technologies, with neodymium (Nd) being critical for permanent magnets and high-performance devices. Therefore, efficient, and sustainable recovery of Nd(III) is essential. This study investigates the liquid-liquid extraction (LLE) of Nd(III) from aqueous chloride solutions using bis(2-ethylhexyl) phosphoric acid (D2EHPA) in toluene under batch conditions. Four parameters, aqueous pH (1.0–3.0), extractant concentration (0.15–0.60 mol L^–1), agitation rate (250–450 rpm) and residence time (5–20 min) were taken and varied in this study. The study used UV-Vis spectroscopy at 583 nm to quantify Nd(III), and FTIR confirmed the metal-extractant complex. The findings show that extraction efficiency increased sharply with pH, achieving around 55% at pH 2.0 and reaching equilibrium near 58% at pH 3.0. An extractant concentration of 0.45 mol L^–1 and agitation at 400 rpm for 15 min yielded optimal recovery while minimizing reagent use and processing time. Triplicate experiments demonstrated reproducibility with a mean relative standard deviation of around 3%. These findings establish a clear mechanistic and parametric understanding of Nd(III) transfer, contributing to conscious solvent extraction and a foundation for intensified processes.

The progress in the magnesium alloy design technology has enabled outstanding characteristics to be achieved for alloys containing both the strengthening LPSO phase (long-period stacking-ordered phase, LPSO) and rare earth elements (Mg–Gd–X, Mg–Nd–X, Mg–Y–X, Mg–Sc–X, and other systems): increase the allowable continuous service temperatures to ~250–300°C, the tensile strength to ~930 MPa, the relative elongation to ~30%, and the hardness to ~190 HV. However, the phenomenon of microgalvanic corrosion arising from the potential difference between the LPSO phase and the α-Mg matrix at their interface, as well as insufficient surface hardness, are the main problems of these alloys, necessitating surface modification for most applications. In this study, the plasma electrolytic oxidation (PEO) technology for treatment of light alloys was modified by adding cerium dioxide (CeO₂) particles to the electrolyte in order to improve the characteristics of oxide layers formed on a Mg–Y–Zn–Yb–Zr alloy with the LPSO phase. The additive concentration (1–5 g/L, with a 1 g/L increment) and the forming pulse frequency of the process current (250 and 1000 Hz) were varied. Consequently, the high-frequency (1000 Hz) PEO with the addition of 4 g/L СeO₂ to the electrolyte allowed the average microhardness to be increased from ~350 to ~690 MPa, i.e., by ~2 times, and the adhesion strength to be improved by 40% relative to the basic variant. The incorporation of CeO₂ had a negligible effect on the corrosion resistance of the layers; the most pronounced positive effect was observed at a PEO frequency of 1000 Hz and at a CeO₂ particle concentration of 1 g/L: the polarization resistance of the oxide layer was ~8.2 MΩ cm², the corrosion current density was ~3.8 nA/cm², and the impedance modulus was ~4.2 MΩ cm² in comparison with the respective characteristics of ~4.3 MΩ cm², ~9.8 nA/cm², and ~3.0 MΩ cm² for the basic oxide layer, which is due to the inert (no chemical reactions involved) incorporation of cerium oxide particles into the layer, its compacted structure, and reduced porosity.

Laser Powder Bed Fusion (L-PBF)—an additive manufacturing technique—enables the manufacturing of high-resolution, complex geometries. However, the process’s steep thermal gradients induce residual stresses that can negatively impact material properties and part performance, often causing cracking, deformation, or compromised component geometry. Consequently, measuring and controlling these residual stresses is essential for successful L-PBF. Several studies have attempted to quantify residual stresses by designing geometries that deform predictably, including the Bridge Curvature Method (BCM). BCM is an indirect measurement approach that evaluates post-production distortion or warpage. It involves cutting a specially designed bridge-type specimen from its substrate, thereby releasing internal stresses and causing physical deformations measured as curvature changes. The magnitude of this curvature correlates with the thermal stresses experienced during fabrication. In this study, we investigate how laser power, scan speed, scan patterns, and second melting strategies affect residual stress and porosity in L-PBF-produced Ti6Al4V bridge-type specimens. Three distinct scan patterns—bidirectional laser scanning (zigzag), unidirectional island scanning (Chessboard 1), and bidirectional island scanning (Chessboard 2)—were each tested in both single-scan and double-scan (second melting) variations. Distortion in the specimens was quantified using BCM and correlated with residual stress levels, while relative density measurements based on Archimedes’ principle were used to determine porosity. The results were analyzed using ANOVA, providing insights and recommendations on how scanning strategies and laser parameters influence residual stress and porosity in Ti6Al4V. As a result, to minimize distortion, the Chessboard 1 strategy is most effective with single pass scanning at a scan speed of 800 mm/s. In contrast, to reduce porosity, the bidirectional scanning strategy yields optimal results with a laser power of 160 W and a scan speed of 900 mm/s.

The true stress-true strain curves of a biomedical grade Co–28Cr–6Mo alloy were obtained through isothermal uniaxial compression tests on a Gleeble-3800 thermo-mechanical simulator. Based on the experimental data, the modified Johnson–Cook model, strain compensated Arrhenius-type model and microstructure-based constitutive model were constructed in a wide range of temperatures (900–1200°C) and strain rates (0.001–10 s^–1). The prediction accuracy of the developed constitutive models was estimated by the determination coefficient and the average absolute relative error between experimental and predicted flow stress values. These values are 0.9857 and 7.8% for the modified Johnson-Cook model, 0.9504 and 13.01% for the strain compensated Arrhenius-type model, and 0.9948 and 2.45% for the microstructure-based constitutive model, respectively. The result clearly demonstrates that the microstructure-based constitutive model is able to describe the hot flow stress behavior more correctly, compared to the other proposed constitutive models.

This study investigated the microstructure and mechanical properties of a Zn–4Ag–1Cu (wt %) alloy processed by high-pressure torsion (HPT) at room temperature through 1 to 10 turns. Microstructural analysis reveals that HPT processing results in the formation of a homogeneous ultrafine-grained (UFG) structure in the alloy samples, with a grain size ranging from 250 to 600 nm, containing nanoscale particles of secondary phases. In the early stages of deformation, after HPT with 1 to 10 turns, a significant increase in strength properties is observed in the UFG samples compared to the initial state. The yield stress and ultimate tensile strength reach 165 and 236 MPa, respectively. An increase in the number of HPT turns from 1 to 10 is accompanied by a decrease in strength and a notable increase in the plasticity of the samples. The elongation to failure increases by an order of magnitude, from 13 to 112 and 250%. Experimental data confirm the manifestation of grain boundary sliding and dynamic recrystallization effects, leading to a significant increase in the plasticity of the UFG alloy at room temperature. This study demonstrates the high efficiency of using the HPT method to form a UFG structure in the Zn–4% Ag–1% Cu alloy, which provides a combination of properties attractive for bioresorbable implants and stents used in medicine.