Search Results (138)

Mg-Li-based dissoluble metal is a promising material for preparing dissoluble magnesium alloy wires. However, there are few reports on the development of Mg-Li dissoluble magnesium alloy wires so far. In this paper, the mechanical properties and dissoluble properties of as-drawn and annealed LA141-0.5Cu wires were investigated in detail. It was found that the tensile strength of the LA141-0.5Cu wires decreased from 160 MPa to 127 MPa and the elongation increased from 17% to 22% after annealing. The difference in corrosion rates (93 °C/3% KCl solution) between the as-drawn wires and annealed wires is not significant, with values of 5.1 mg·cm⁻²·h⁻¹ and 4.5 mg·cm⁻²·h⁻¹, respectively. This can be explained as follows: after annealing, the number of dislocations in the wire decreases, the strength decreases, and the plasticity increases. The reason why the wires have a significant corrosion rate is that there is a large potential difference between the Cu-containing second phase and the magnesium matrix, which forms galvanic corrosion. The decrease in dislocation density after annealing leads to a slight reduction in the corrosion rate of the wires. This work provides a qualified material for fabricating temporary blocking knots for the exploitation of unconventional oil and gas resources. Full article

A critical barrier to the clinical translation of biodegradable magnesium (Mg)-based materials lies in their rapid degradation rate in physiological environment, which leads to premature structural failure and compromised cytocompatibility. Micro-arc oxidation (MAO) coatings offer preliminary corrosion mitigation for Mg alloys, while their inherent structural porosity compromises long-term durability in physiological environment. To address this limitation, we developed a hierarchical coating system consisting of a dense Mg(OH)₂ interlayer (MAO/HT) superimposed on the MAO-treated substrate, followed by a functional polydopamine (PDA) topcoat to create a MAO/HT/PDA composite architecture. The surface characteristics and crystalline structures of these coatings were systematically characterized using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion resistance and interfacsial stability in physiological environment were quantitatively assessed through electrochemical analyses and long-term immersion tests in simulated body fluid (SBF). The cytocompatibility of the coatings was assessed by directly culturing osteoblast on the coated samples. The results reveal that the Mg(OH)₂ film possesses a bulk-like structure and effectively seals the micro-pores of the MAO coating. The current density of MAO/HT/PDA sample decreases by two orders of magnitude compared to that of MAO sample, indicating excellent corrosion resistance. The PDA layer not only acts as a strong barrier to improve the corrosion performance of the coating but also helps maintain the stability of the coating, thus delaying coating destruction in SBF. Moreover, the osteoblast culture results suggest that the MAO/HT/PDA coating promotes cell spread and proliferation noticeably compared to both the MAO and MAO/HT coatings. This study provides compelling evidence that the Mg(OH)₂/PDA composite coating is biodegradable and offers outstanding protection for micro-arc oxidized magnesium. As a result, it holds great promise for significant applications in the field of orthopedic medicine. Full article

Heusler compounds and alloys constitute a burgeoning class of materials with exceptional properties, holding immense promise for advanced technologies. Electronic band structure calculations are instrumental in driving research in this field. Nowotny–Juza compounds are similar to Semi-Heusler compounds containing one instead of two transition metal atoms in their chemical formula. Recently, they have been widely referred to as “$p^0$-d or $d^0$-d Semi-Heusler compounds”. Building upon our previous studies on $p^0$-d or $d^0$-d Semi-Heusler compounds featuring Li or K, we now explore a new class of $d^0$-d compounds incorporating alkaline earth metals and more specifically Mg which is well-known to occupy all possible sites in Heusler compounds. These compounds, with the general formula MgZ(Ga, Ge, or As), where Z is a transition metal, are investigated for their structural, electronic, and magnetic properties, specifically within the context of the three possible $C{1}_{\mathrm{b}}$ structures including also the effect of tetragonalization which is shown not to affect the equilibrium cubic type. Our findings demonstrate that a significant number of these compounds exhibit magnetic behavior, with several displaying half-metallicity, making them highly attractive for spintronic applications. This research provides a crucial foundation for future experimental investigations into these promising materials. Full article

In this study, high toughness and superplastic deformability were achieved in Mg-9Li alloys through dual-phase microstructure optimization. Solid solution (SS) and equal channel angular pressing (ECAP) treatments were employed to refine the alloy’s microstructure. The effects of these treatments on room-temperature and low-temperature high-strain-rate superplasticity were systematically investigated under varying microstructural conditions. Results demonstrate that the SS-ECAP alloy exhibits outstanding superplasticity at room temperature and remarkable high-strain-rate deformation capability, achieving a maximum fracture elongation of 602.1%. Grain refinement and reduced dislocation density promote uniform void nucleation under high strain. Calculations of the strain rate sensitivity index (m-value) and activation energy (Q) reveal that the superplastic behavior in the SS-ECAP state is predominantly governed by grain boundary sliding facilitated by grain boundary diffusion. These findings provide critical insights into advancing the superplastic forming technology of Mg-9Li alloys. Full article

This study investigates the enhancement of corrosion resistance in magnesium-lithium alloys through plasma electrolytic oxidation (PEO) coatings incorporating ZnF₂ via in situ synthesis. By adjusting Zn²⁺ concentrations (4–16 g/L) in a zirconium salt-based electrolyte, ceramic coatings with tailored ZnF₂ content, thickness, and porosity were fabricated. The optimal Zn²⁺ concentration of 12 g/L yielded a ZnF₂-rich coating with isolated pores and enhanced densification (inner layer resistance R_i = 3.01 × 10⁴ Ω⋅cm²), achieving a corrosion current density (i_corr) of 4.42 × 10⁻⁸ A/cm² and polarization resistance (Rp) of 8.5 × 10⁵ Ω⋅cm², representing a 354-fold improvement over untreated LA103Z. Higher Zn²⁺ concentrations (16 g/L) induced interconnected pores and ZnO formation, degrading corrosion resistance. Long-term immersion (168 h in 3.5 wt% NaCl) confirmed the durability of Zn₁₂ coatings (mass loss: 0.6 mg), while Zn₄ and Zn₁₆ coatings exhibited severe localized corrosion. The study demonstrates that balancing Zn²⁺ concentration optimizes ZnF₂ passivation and pore isolation, offering a scalable strategy for Mg-Li alloy protection in corrosive environments. Full article

Mg-Li alloy is widely used in aerospace and military equipment, but the research on its micromechanical mechanism is still insufficient. In this paper, molecular dynamics simulation is used to analyze the nano-indentation response and mechanical mechanism of single crystal Mg-Li. The deformation and hardness changes of Mg-Li under different loads were studied by load–displacement and hardness–depth curves. At the same time, the dislocation defects and equivalent stress are analyzed to reveal the dislocation formation and stress distribution in the process of deformation. Finally, under the condition of stress relaxation, the mechanical behavior of Mg-Li in the process of nano-indentation was revealed, and the deformation mechanism of Mg-Li alloy was studied. Full article

Due to the specific application of aluminum–magnesium–lithium (Al-Mg-Li) alloys in the transportation industry, it is necessary to consider the influence of microstructure development on material degradation under severe environmental conditions. This degradation was simulated according to the standard test method ASTM G34-01 (2018) on a newly designed and synthesized Al-2.1Mg-1.92Li alloy in the as-cast condition. The degradation susceptibility of the alloy was estimated by measuring the changes in the sample mass and microhardness, and the pH and chemical composition of the environment with respect to the exposure time. The influence of the microstructure constituents on the degradation of the alloy was determined using metallographic analysis of the exposed surface and cross-section of the samples after testing. During the degradation, dealloying of the α_Al matrix through Li, Mg and Al component dissolution resulted in a decrease in the mass of the samples, an increase in the pH of the environment and changes in its chemical composition. This observation was also confirmed by the results of the metallographic analysis. The degradation involved the formation of cavities around the Al₈Mg₅ (β) and Al₂LiMg (T) intermetallic phases through an anodic dissolution mechanism. The increase in microhardness values after exposure indicated an increase in the stress around the degradation front due to the wedge effect of the degradation products. The results of the investigation support the potential application of the synthesized Al-2.1Mg-1.92Li alloy under the severe environmental conditions defined by the ASTM G34-01 (2018) standard. Full article

The Mg-8Li-3Al-0.3Si dual-phase alloy (LA83-0.3Si) was subjected to six multi-directional forging (MDF) passes in the present work, then its microstructure, mechanical properties, and work hardening and work softening effects were examined and analyzed. The results indicate that the continuous dynamic recrystallization (CDRX) mechanism of the LA83-0.3Si dual-phase alloy gradually transitioned to a discontinuous dynamic recrystallization (DDRX) mechanism as the temperature increased after MDF. This temperature change induced a transition in the basal texture from bimodal to multimodal, significantly reducing the texture intensity and weakening the alloy’s anisotropy. At 310 °C, the AlLi phase nucleated into coated particles to stabilize the structure. Additionally, the increase in the forging temperature weakened the synergistic deformation capability of the α/β phases, while the hardening behavior of the β-Li phase provided a nucleation pathway for dynamic recrystallization (DRX). MDF significantly enhanced the strength and ductility of the LA83-0.3Si alloy. The alloy’s strength continued to rise, while elongation decreased as the forging temperature increased. The ultimate tensile strength (UTS) and elongation (EL) reached 267.8 MPa and 11.9%, respectively. The work hardening effect increased with the forging temperature, whereas the work softening effect continuously diminished, attributed to the enhanced hardening behavior of the β phase and the reduced ability to transfer dislocations. Full article

The energy transition can only be achieved if the global energy sector is transformed from a fossil-based system to a zero-carbon-based source system. To achieve this aim, two technologies have shown promising advances in high-temperature application. Concentrating solar power (CSP) plants are seen as a key technology to achieve the needed energy transition, and carbon dioxide (CO₂) capture and storage (CCS) is a promising technology for decarbonizing the industrial sector. To implement both technologies, molten carbonate salts are considered promising material. However, their corrosive behavior needs to be evaluated, especially at high temperatures, where corrosion is more aggressive in metal structures. This paper presents an experimental evaluation of the static corrosion of two molten carbonate salts, a Li₂CO₃-Na₂CO₃-K₂CO₃-LiOH∙H₂O (56.65-12.19-26.66-4.51wt.%) mixture and a Li₂CO₃ salt, under an air atmosphere with five corrosion-resistant metal alloys, including Alloy 600, Alloy 601, Alloy 625, Alloy 214, and Alloy X1. In this study, the corrosion rate and mass losses were quantified. In addition, in all the cases, the results of the experimental evaluation showed corrosion rate values between 0.0009 mg/cm²·yr and 0.0089 mg/cm²·yr. Full article

The body-centered cubic (BCC)-structured magnesium–lithium (Mg-Li) alloy is the lightest metal material, but its mechanical properties are poor, especially its strength. In this study, the effect of adding rare earth Y on the microstructure and mechanical properties of as-cast BCC Mg-11Li-6Zn-xY (x = 0, 0.5, 1.2, and 2, in wt.%) alloys was investigated. The results revealed that massive amounts of nano-scale θ (MgLiZn) and/or θ’ (MgLi₂Zn) precipitated inside the grains, and some θ phases precipitated at the grain boundaries in the Mg-11Li-6Zn alloy. With the addition of Y, W phases formed at the grain boundary, their content gradually increased with the Y concentration, and the grain size decreased simultaneously. The Mg-11Li-6Zn-0.5Y alloy exhibited higher ultimate tensile strength (190 MPa) and elongation (27%) at room temperature than those (170 MPa and 22%) of the Mg-11Li-6Zn alloy, presenting improvements of 11.8% and 22.7% in strength and ductility, respectively. The improvements in the mechanical properties of the Mg-11Li-6Zn alloy achieved by adding less Y could be attributed to the formation of moderate W phases and a reduction in grain size. However, once the addition of Y became excessive, the mechanical properties of the Mg-11Li-6Zn-1.2Y alloy were reduced due to the formation of too many reticular W phases. In addition, the Mg-11Li-6Zn-2Y alloy containing the highest Y content had the lowest ultimate tensile strength, 163 MPa, and highest ductility, 38%, due to the combined effect of the most reticular W phases and the smallest grains. Furthermore, the fracture morphology of the Mg-11Li-6Zn alloy displayed apparent necking, which became insignificant after the addition of Y, indicating that this addition could improve its uniform plastic deformation ability. Full article

Heat treatment processes play a pivotal role in optimizing the microstructure and mechanical properties of Mg-Li alloys, thereby enhancing their performance and expanding their potential applications in structural and lightweight engineering fields. In this study, the influence of solution and aging treatments on the microstructure, phase transformation, and microhardness of friction-stir-processed (FSPed) LAZ931 Mg-Li alloy was investigated to obtain the optimal solution treatment temperature and time. An optimal solution treatment at 460 °C for 0.5 h under an Ar gas atmosphere facilitated complete α-phase dissolution with subsequent aging at 125 °C, triggering precipitation-mediated hardening. An X-ray diffraction (XRD) analysis identified a new MgLi₂Al phase in the stirring zone (SZ) in addition to the α, β, and AlLi phases. Aging kinetics at 125 °C showed that SZ hardness increased to 110.5 HV after solution treatment, which was 5.3% higher than the base metal (BM). After 3 h of aging, microhardness peaked at 86.5 HV before decreasing due to the decomposition of the metastable MgLi₂Al phase into the stable AlLi phase. The microhardness stabilized at around 78 HV, which was 16.2% higher than that of the original SZ. These experimental results provide a fundamental understanding of property structure for meeting the growing demand for lightweight materials and improving material properties. Full article

Al-Mg-Li alloy is an ideal lightweight structural material for aerospace applications due to its low density, high specific strength, and excellent low-temperature performance. This study examines the mechanical properties and microstructural evolution of Al-Mg-Li alloy subjected to cryogenic and room temperature cold rolling, which induces large plastic deformation. Compared with room temperature rolling, cryogenic rolling significantly reduces surface cavity formation, thereby enhancing the alloy’s rolling surface quality. After cryogenic rolling by 80% and subsequent natural aging, the yield strength of artificially aged Al-Mg-Li alloy reaches 560 MPa, delivering a 60% increase compared to the traditional T6 state with a slight reduction in elongation from 6.5% to 4.6%. The specific strength achieves 2.23 × 10⁵ N·m/kg, outperforming conventional Al-Cu-Li and 7xxx-series Al alloys. The depth of intergranular corrosion decreases from 100 µm to 10 µm, demonstrating excellent corrosion resistance enabled by the new method. Transmission electron microscopy reveals that finely distributed δ′ (Al₃Li) is the primary strengthening phase, with high-density dislocations further enhancing strength. However, coarsening of δ′ (from ~2.9 nm to >6 nm) induced by ensuing artificial aging results in coplanar slip and reduced elongation. Lowering the post-aging temperature inhibits δ′ coarsening, thereby improving both strength and elongation. Our results provide valuable insights into optimizing the properties of Al-Mg-Li alloys for advanced lightweight applications. Full article

Rare earth elements (REEs) possess unique physical and chemical properties that render them indispensable in various industries, including electronics, energy production and storage, hybrid and electric vehicles, metallurgy, and petro-chemical processing. The criticality of REE underscores the need to enhance the efficiency of primary resource extraction and promote circularity through increased recycling from secondary sources. This paper provides a brief overview of REE recovery from secondary sources, particularly waste from electronic and electric equipment (WEEE). The discussion encompasses direct reuse of magnets, short-loop recycling (direct recycling), hydro- and pyrometallurgical processes, highlighting microwave (MW) technology. Original results are presented, focusing on the recovery of neodymium (Nd) from permanent magnet scraps from hard disk drives (HDD-PC) using microwave-assisted liquid metal extraction (LME) with magnesium (Mg) as the extractant. The subsequent separation of Nd from the Mg-Nd alloy via vacuum Mg distillation that is reused in the process is described. The experimental study demonstrates that the LME process, conducted in a microwave furnace, is a viable method for recovering Nd from permanent magnet scraps, which are essential for reducing the environmental impact of REE extraction and promoting a circular economy. By separating Nd from the alloy through vacuum distillation (450–550 mmHg), at temperatures of 850–900 °C for 8 h, a Nd sponge with a content of 95–98 wt.% Nd was obtained. The extracted content of Nd in the Mg alloy increases with increasing temperature and holding time. It was found that ≈ 97% of the Nd in the scrap was extracted from 2 to 5 mm crushed scrap at 800 °C for 8 h, using a LiF-LiCl-MgF₂ protecting flux in a furnace Ar atmosphere. Full article

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and carefully controlling the composition of the slag. This research work focused on finding the optimal smelting procedure for extracting ferro-nickel from calcined nickel ore. Comparing experimental data to the results of thermodynamic modeling using Factsage 8.2 software was a key part of the study. The nickel smelting process, which involved a carbon consumption of 4 wt.%, resulted in ferro-nickel with an Fe/Ni ratio of 4.89 and slag with a nickel content of just 0.017%. The structure and properties of nickel slag in the MgO-SiO₂-FeO system were investigated by observing the changes in the MgO/SiO₂ ratio. This study found a significant nickel recovery degree of 95.6% within the optimal M/S ratio range of 0.65 to 0.7. When the M/S ratio exceeds 0.7, iron-rich magnesium silicates (Mg_xFe_ySiO_2+n) are generated within the slag. These compounds are released downwards due to their higher specific weight, restricting the movement of small metal particles and contributing to increased metal loss through the slag. Optimized slags could revolutionize smelting, increasing metal recovery while minimizing environmental impact. Full article

In this work, the Mg-8Li-3Al-0.3Si (LAS830) alloy was prepared by the vacuum melting method. The as-cast alloy was subjected to backward extrusion at 250 °C and then spun at 250 °C. The microstructure and mechanical properties of the alloy during deformation were studied. The results showed that the LAS830 alloy primarily consisted of α-Mg and β-Li phases, and the AlLi, MgLi₂Al, and Mg₂Si phases were dispersed. After backward extrusion, the grains and AlLi phase were refined, the β-Li phase recrystallized, and the fine MgLi₂Al phase precipitated. The spinning of the extruded alloy tubes resulted in the lamellar distribution of an α/β duplex microstructure, with even finer grains and more dispersed precipitates. The combined deformation significantly enhanced the alloy’s strength and ductility, with the ultimate tensile strength reaching 235.4 MPa and an elongation of 15.74%. In addition, the average hardness of the α/β phase increases after backward extrusion, but the average hardness of the β-Li phase increases further after spinning. The as-cast LAS830 alloy exhibited a high work hardening rate but a low softening rate. With reverse extrusion, the work hardening rate decreased and the softening degree increased. Compared with backward extrusion, the work hardening rate and softening degree of the LAS830 alloy was reduced after spinning due to the combined effect of the lamellar distributed duplex microstructure and the dispersed second phases in the alloy, while its softening rate increased. Full article