Mg-Li Alloy Research Articles

Effects of ultrasonic treatment and current pulse frequency on properties of micro-arc oxidation coating on Mg alloy LAZ931

To enhance corrosion resistance of magnesium-lithium (Mg-Li) alloy LAZ931 in corrosive environments, a micro-arc oxidation (MAO) based surface treatment was carried out under a unipolar pulsed power supply. Effects of ultrasonic treatment and current pulse frequency on the performance of MAO coatings were investigated using scanning electron microscopy, electrochemical characterization, and friction wear tests. Results demonstrate that ultrasonic treatment greatly reduced the number density of micro-defects in the resulting MAO coatings and improved their overall performance. Corrosion and wear resistance of the MAO coating increased when current pulse frequency increased from 400 to 2000 Hz. Those findings are beneficial for improving the performance of MAO on Mg-Li alloys through optimizing the processing parameters.

Application of an in vitro neuroinflammation model to evaluate the efficacy of magnesium-lithium alloys.

Mg-Li alloys can be promising candidates as bioresorbable Li-releasing implants for bipolar disorder and other neurodegenerative disorders. In order to compare the therapeutic efficacy of conventional Li salts and Li delivered through Mg-Li alloy extracts, we tested an in vitro model based on the neuroinflammation hypothesis of mood disorders (peripheral inflammation inducing neuroinflammation) wherein, a coculture of microglia and astrocytes was treated with conditioned medium from pro-inflammatory macrophages. Two alloys, Mg-1.6Li and Mg-9.5Li, were tested in the form of material extracts and well-known outcomes of Li treatment such as GSK3β phosphorylation (indirect flow cytometry) and influence on inflammation-related gene expression (qPCR) were compared against Li salts. This is the first study demonstrating that Li can increase the phosphorylation of GSK3β in glial cells in the presence of excess Mg. Furthermore, Mg-Li alloys were more effective than Li salts in downregulating IL6 and upregulating the neurotrophin GDNF. Mg had no antagonistic effects toward Li-driven downregulation of astrogliosis markers. Overall, the results provide evidence to support further studies employing Mg-Li alloys for neurological applications.

Strengthening dual-phase Mg-Li alloy through precipitation control

Strengthening dual-phase Mg-Li alloy through precipitation control

Effects of heat input on microstructures and mechanical properties of LAZ931 magnesium-lithium alloy in High-Speed TIG welding

LAZ931 magnesium-lithium (Mg-Li) alloy is a novel ultra-light alloy material. This research investigates the Tungsten Inert Gas (TIG) welding process of a 2.15 mm thick LAZ931 magnesium-lithium alloy thin plate without wire filling. The objectives are to determine the appropriate heat input range, achieve welded joints with good forming quality, and examine the effect of heat input on the microstructure and mechanical properties of the welded joints. The results show that post-TIG welding at high welding speed, the melt width of the entire welded joints is very narrow only about 9 mm, and a small amount of MgLiAl2 (θ) phase and AlLi (γ) phase precipitate in the weld seam zone(WSZ), while a significant amount of θ phase precipitates in the heat-affected zone (HAZ), making the HAZ the highest in strength due to precipitation strengthening. With increasing heat input, the quantity of θ phase decreases, resulting in reduced strength and hardness but increased plasticity in the HAZ. The highest hardness in the HAZ was measured at 87.6 HV, with the base material (BM) exhibiting the lowest hardness. The tensile strength of the joint reaches 163.2 MPa, with an elongation of 23.9 %, and the fracture mode is a mixed ductile–brittle fracture.

Mechanical property and corrosion performance in the as-rolled Mg-8Li-4Gd-1.5Ni alloy

As for the magnesium-lithium (Mg-Li) alloys for the applications of rapid corrosion material, enhancing their mechanical properties while maintaining the degradation rate poses a significant challenge. Simultaneously, it is crucial to elucidate the behavior of the long period stacking ordered (LPSO) phase in the corrosion process of as-rolled Mg-Li alloys. This study prepared the as-rolled Mg-8Li-4Gd-1.5Ni alloy with rolling reductions of 30 %, 50 %, 70 %, and 90 % at room temperature. Results indicate that, during the rolling process, the reticular LPSO gradually transitions to a fibrous LPSO and the GdNi3 particles are refined. Additionally, the amounts of twin increases. The alloy with 30 % reduction exhibits the highest corrosion rate, with a weight loss rate of 0.50 mg·cm−2·min−1 in a solute of 3 % KCl. The tensile strength reaches a maximum of 247 MPa. The increase in tensile strength is achieved at the expense of plasticity. The bending of the LPSO phase, the fracture of the secondary phases, and the increase in dislocations and twins increase the chemical reactivity of the alloy, leading to a higher corrosion rate. Rolling brings about the increase in dislocation density, dislocation entanglement, and the reduction in grain size, which indicate that the strengthening mechanisms of the alloy after rolling include work hardening and grain refinement strengthening.

Effect of introduction of MXene on low energy plasma electrolytic oxidation

This article discusses the development of 2D MXene-containing coatings on magnesium alloy LA91, which are produced using low-energy plasma electrolytic oxidation (LePEO) processing. The coatings enhance substrate corrosion resistance and offer improved wear resistance. Notably, the coatings exhibit increased corrosion and wear resistance, as well as higher microhardness, while simultaneously reducing the voltage required for the PEO process. The addition of MXene to electrolyte enhances its conductivity, leading to the incorporation of MXene into the oxide coating. Despite a reduction in coating thickness, the resulting coatings demonstrate excellent corrosion resistance, wear resistance, and hardness. The MXene-enriched PEO coatings show impressive performance metrics compared to the MgLi alloy substrate. The corrosion current density of the MXene-enriched coatings is only 3.3 % of that of the MgLi alloy, while the average friction coefficient is reduced to 39.9 %, and the hardness is 6.6 times greater. Additionally, the coatings exhibit enduring corrosion resistance during prolonged immersion and neutral salt spraying tests. These performance improvements are attributed to MXene's ability to hinder the transmission of corrosive media, as well as its interlayer shear and self-lubrication properties, which enhance wear resistance.

Effect of I-phase formation on hydrogen embrittlement behaviour of as-cast Mg-8 wt%Li based alloys

By performing microstructural characterization, tensile testing and failure analysis, the effects of electrochemical H-charging on microstructure and mechanical behaviour of two as-cast Mg-8Li (in wt%) based alloys were investigated and compared. Due to the in-situ formation of I-phase, the failure elongation ratio for Mg-8Li-6Zn-1Y alloy was 31.2 % and its hydrogen embrittlement (HE) susceptibility was about 1/4 that of Mg-8Li alloy after H-charging for 24 h. Moreover, the preferential location of H-induced pores transferred from two matrix phases to I-phase/matrix eutectic pockets due to the preferential H absorption of I-phase, resulting in the higher HE resistance of Mg-8Li-6Zn-1Y alloy.

Boosting corrosion resistance of Mg-Li alloy: Implanting bioinspired superhydrophobic surfaces into MAO matrix for enhanced protection

The corrosion problem has significantly impeded the practical application of Mg-Li alloys. In this report, a method that combines micro-arc oxidation (MAO) with electrochemical deposition is developed to create a superhydrophobic matrix on Mg-Li substrate. The combination approach harnesses the superiority of both coverages, including MAO as the dense, firmly bonded ceramic oxide layer on the metal substrate and the superhydrophobic surface (SHS) implanted into MAO matrix. The MAO-SHS coating exhibits high mechanical stability, maintaining the superhydrophobicity due to the “implanting effect” even after a long distance of friction effect. For corrosion inhibition, compared to the bare Mg-Li with icorr of 9.26 × 10−5 A/cm2, the icorr for MAO and MAO-SHS is 7.83 × 10−6 A/cm2 and 7.50 × 10−9 A/cm2, respectively, representing the reduction of approximately one and four orders of magnitude. Focusing the atmospheric corrosion inhibition, MAO-SHS proves to manipulate the dynamic evolution of saline solution evaporation and salt particle deliquation. The salt particle crystalized from saline solution on MAO-SHS is found to have significantly smaller contact area than that of the bare Mg-Li and MAO. By employing atomic force microscopy, the adhesion force of salt particle is revealed as ca. 45 nN, 13 nN, and 2 nN for salt particle on Mg-Li, MAO, and MAO-SHS, respectively. This suggests that the salt can be more easily removed from the MAO-SHS surface, thereby reducing the susceptibility to corrosion. The in situ deliquation is conducted to understand the formation of the droplet on different surfaces. The air in the SHS layer hinders chloride ingress and the SHS layer seals the pores in MAO layer, proving the synergistic effect afforded by MAO-SHS to achieve superior corrosion resistance.

Effect of Y content on microstructure evolution and tensile properties of Mg-8Li-3Al-2Sn-xY alloys

Abstract The design of new ultra-light Mg-Li alloys have great significance in aerospace and other fields. In this paper, Sn and Y elements were simultaneously added into Mg-8Li-3Al (wt%) alloy and the effect of Y content on microstructure evolution and tensile properties of Mg-8Li-3Al-2Sn-xY (wt%) alloys was studied. The as-cast Mg-8Li-3Al-2Sn alloy is composed of α-Mg + β-Li duplex-phase matrix, fine MgLiAl2 phase and coarse fishbone-like Li2MgSn phase. As Y element is added, granular Al2Y phase is formed, and grain size of α-Mg phase decreases significantly with shape changing from well-developed coarse dendritic to equiaxed dendritic. After hot extrusion, α-Mg phase is elongated along the extrusion direction, and β-Li phase undergoes complete dynamic recrystallization and transforms into fine equiaxed grains. The addition of 0.5% Y improves the tensile properties of as-cast Mg-8Li-3Al-2Sn-0.5Y alloy. However, the tensile properties show a downward trend with further increase of Y content. Hot extrusion significantly enhances the tensile properties of Mg-8Li-3Al-2Sn-xY alloys. Similarly, strength reaches the highest when the Y content is 0.5% for extruded Mg-8Li-3Al-2Sn-xY alloys.

Environmentally benign bioinspired oleogel infused surface based on edible sunflower seed oil: Preparation and corrosion mitigating for Mg-Li alloy

The production of metals is an essential process to contribute carbon dioxide emission. Being exposed in natural and industrial environment, metal endures corrosion, which in turn leads to significant material loss. Thus, protecting metal from corrosion is not just a matter of material preservation but also a critical aspect for promoting environmental sustainability. Acting as a barrier, traditional organic coating is widely adopted to prevent metal from corrosion. However, over time, the coating degradation contributes to the growing problem of microplastic pollution. Given these concerns, the challenge lies in developing sustainable, environmentally friendly methods for protecting metals from corrosion. Bioinspired slippery liquid-infused porous surface (SLIPS) has emerged as advantageous solutions for corrosion protection. In this study, firstly, a bioinspired superhydrophobic coating is constructed onto a highly active Magnesium-lithium (Mg-Li) alloy via a one-step electrodeposition. Following that, an edible beeswax-sunflower seed oil is used to form a composite oleogel-infused surface (OIS), one category of SLIPS. Traditional characterization, such as high-resolution transmission electron microscopy (HRTEM), and sophisticated X-ray computed tomography (X-CT) reveal the detailed microstructure and composition of the coatings. The corrosion resistance of OIS surfaces significantly surpasses that of superhydrophobic surfaces, as evaluated by scanning Kelvin probe (SKP), electrochemical impedance spectroscopy, and potentiodynamic polarization curve. The OIS exhibits a high corrosion inhibition efficiency of 99.99%, far exceeding that of the superhydrophobic surface. Furthermore, the OIS demonstrates self-healing capability, with waxy components undergoing phase transition to repair surface damage caused by scratching. This environmentally sustainable biomimetic coating affords versatility and long-term corrosion protection for Mg-Li alloy, paving a new way for their extensive utilization in various fields.

Investigation of in-situ ion release and surface film formation of hcp Mg-Li thin films

In this work, the dissolution process of magnetron sputtered Mg-Li thin films was investigated by in-situ flow cell/ICP-MS measurements and ex-situ ICP-MS measurements after longer immersion and additional XPS measurements. High Li concentrations are released due to a Li rich carbonate layer formed in air. The depletion of Li leads to preferred Mg release before preferred Li release occurs due to the higher activity of Li and incorporation of Mg in corrosion products. This data provides a baseline for developing release profiles for medical application, more generally, it unravels details of the corrosion mechanism of lightweight MgLi alloys.

Mao-based solid-like slippery composite coating with superior corrosion resistance and robust machinery performance upon magnesium-lithium alloy LA81

Slippery liquid-infused porous surface exhibits a great potential for corrosion management with super repulsive water properties, whilst their poor adhesion to underlying materials and durability of lubricants remains a challenge. In this work, a micro-arc oxidation (MAO)-based solid-like slippery composite coating (SSC) is developed upon Mg-Li alloy LA81 by combining mechanical pinning effects of MAO and super repulsive water performance of SSC, which maximizes adhesion strength, water repulsion and sustainable corrosion protection. The SSC coatings exhibit liquid-to-solid transition under the curing effect of epoxy resin. Efficient sealing of the MAO layer is yielded through high fluidity of the liquid phase of SSC. Cured SSC can further strengthen the interface bonding with respect to underlying MAO layer, and significantly alleviate lubricant loss.

Coordinated deformation characteristics and its effect on microstructure evolution of LA103Z Mg-Li alloy in reciprocating rotary extrusion

The uneven metal flow and inhomogeneous microstructure on the cross-section of the extruded bar are mainly induced by the uncoordinated deformation during the traditional extrusion process, which seriously restricts its production and application. These defects are more prominent for the dual-phase Mg-Li alloy due to the phase transformation and the difference in flow between soft and hard phases. In order to solve the uncoordinated deformation in traditional extrusion, the reciprocating rotary extrusion (R-RE) process based on harmonic oscillation of die is proposed. The experiment and numerical simulations of the reciprocating rotary extrusion process were carried out at rotating frequency of 2.5 and 5 Hz, extrusion velocity of 1 mm/s, forming temperature of 290℃, die extrusion ratio of 12 and die rotating angle of ±6°. The coordinated deformation mechanism from macroscopical flow and microstructure in reciprocating rotary extrusion was investigated deeply. Meanwhile, a novel theoretical method was proposed to describe coordinate deformation characteristics quantitatively. The results indicated that the reciprocating rotary extrusion significantly reduces the forming load and accumulates more strain. The more uniform metal flow contributes to coordinated deformation. The extrusion deformation factors are proposed to reveal the coordinated deformation mechanism. In addition, the deformation body characteristic zone is novelly divided into six zones by combination of flow pattern and microstructure evolution.

Effective strategies for improving the mechanical stability of aged Mg-Li alloys

To date, the aging softening of Mg-Li-Zn based alloys has been a critical issue limiting their industrial application. Here, we design a new Mg-Li alloy that exhibits exceptional mechanical stability after solution treatment and then water quenching by means of a hitherto unrecognized mechanism. The results indicate that precipitation of a semi-coherent MgLi2(ZnAg) phase leads to rapid age-hardening of the Mg-Li alloy after water quenching, as evidenced by the Ag atoms in the precipitate. A massive solid solution of Ag atoms in the β-Li phase strengthens the stability of the alloy and retards the diffusion of Li atoms from the β phase into the α matrix during aging. Zn atoms in the MgLi2Zn precipitate are replaced by Ag atoms which explain the origin of age-hardening and inhibit the evolution of the substable strengthened phase MgLi2Zn to the equilibrium softened phase MgLiZn. This research may contribute to the theoretical basis for solving the age-softening problem of Mg-Li alloys.

Cultivating resilience: A skin-inspired sandwiched self-healing coating for shielding Mg[sbnd]Li alloy from corrosion

The utilization of MgLi alloy has garnered significant attention due to its potential for various applications. However, its vulnerability to corrosion remains a challenge that should be overcome for widespread use. In response to this challenge, we present a skin-inspired self-healing coating, applied to micro-arc oxidation (MAO)-treated MgLi alloy. The coating is composed of epoxy resin, polyvinyl alcohol (PVA) and tannic acid (TA). Like the animal skin, epoxy resin acts as the epidermis, which blocks the invasion of the external corrosive species. Even being damaged by the mechanical effect, the inner PVA and TA polymer connects by hydrogen bonding, which exhibits a swelling effect in aqueous medium to heal the damage area. Even water penetrates into the underneath substrate, TA as the corrosion inhibitor will react with Mg2+ to form tannate as the inner layer to prohibit further corrosion. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy and atomic force microscopy are utilized to characterize the microstructure, chemical composition and topology of the coating. Corrosion protection experiments demonstrate that the MAO-PVA/TA-epoxy coating exhibits high anti-corrosion ability compared to MAO-PVA/TA and MAO coating. The |Z|0.01Hz value of 1.13 × 109 Ω cm2 is two and six orders of magnitude higher than the other two coatings. An in-depth comprehension of the self-healing process is achieved through ex situ examination utilizing SEM and energy-dispersive spectroscopy techniques. For real-time observation of the self-healing process of the coating, we employ a scanning vibrating electrode technique and a three-dimensional digital microscope. The reported coating, endowed with self-healing capabilities, holds tremendous promise for expanding the scope of applications for MgLi alloy in the realm of science and engineering.

Effect of V2O7 4− anion intercalation on the microstructure and corrosion resistance of MgAl Layered Double Hydroxides films on LA43M Mg-Li alloy

ABSTRACT To improve the corrosion resistance of LA43M alloy, MgAl-NO3 −-Layered Double Hydroxides (LDH) was prepared on the surface of the alloy by an in situ hydrothermal method, and uniform and dense MgAl-V2O7 4−-LDH films were successfully obtained by ion-exchange over different times. SEM, XRD, EDS, electrochemical polarisation, EIS and hydrogen evolution experiments were conducted to analyse microstructure and corrosion resistance of these films. The results verified that with increase of the ion-exchange reaction time, the nanosheets of the MgAl-V2O7 4−-LDH film are larger in size, uniformly distributed, and slightly increased in thickness. The surface of the modified MgAl-V2O7 4−-LDH film grown for 4 h on the surface had a staggered and tilted manner, and the gaps between the nanosheets were small, making it more effective in blocking the corrosive medium. The MgAl-NO3 −-LDH film modified by V2O7 4− anion intercalation can further improve the corrosion resistance of the LA43M alloy.

In-Situ Lithium Analysis In MgLi Alloys Using Laser-Induced Breakdown Spectroscopy with a Compact Chamber.

This study explores the feasibility of in situ Lithium (Li) analysis in Magnesium-Lithium (MgLi) alloys using Laser-Induced Breakdown Spectroscopy (LIBS). It focuses on two Li emission lines: Li I 670.8 nm (resonance) and Li I 610.4 nm (non-resonance). Comparing characteristics at atmospheric and low pressures, self-reversal signatures are observed in both emission lines at atmospheric pressure, complicating the analysis. Challenges in suppressing self-reversal effect using laser energy and detection window adjustments are noted. To address this, a compact chamber (80 mm×50 mm×50 mm) with adjustable pressure (using a portable vacuum pump) is developed. Lowering the pressure significantly reduces self-reversal effect, particularly for the Li I 610.4 nm line. This makes Li I 610.4 nm more suitable for analyzing high Lithium concentrations in MgLi alloys. Using standard samples, such as LA91 (8 % Li) and LA141 (14 % Li), the study successfully obtains Li I 610.4 nm spectra with proportional Li emission intensities. Even with a commercially affordable time-integrated charge-coupled device (CCD) detection system, the results indicate the efficacy of this approach for in situ Li analysis in MgLi alloys.

Improvement of Corrosion and Wear Resistance of Mg-Li Alloy by Binary- and Ternary-Layered Double Hydroxide/Steam Coating Composite Coatings

Improvement of Corrosion and Wear Resistance of Mg-Li Alloy by Binary- and Ternary-Layered Double Hydroxide/Steam Coating Composite Coatings

Atomized Mg-Li spherical alloys: A new strategy for promoting reactivity of Mg

In this study, to improve the reactivity Mg, which is a frequently used fuel, Li was incorporated into it. Mg-Li alloys with 3 and 5 wt% Li, prepared via centrifugal atomization, displayed a high degree of sphericity and consisted of αMg. Thermal behaviors indicated that the initiation oxidization temperature of Mg-Li powders was ∼170–200°C lower than that of pure Mg, owing to the lower melting point of soluble Li than that of Mg. Li passes through oxide shells and initiates the oxidization of metals in the core. The apparent activation energy of Mg decreased significantly from ∼361.2 kJ/mol to ∼141.1 kJ/mol with the incorporation of Li. For combustion in air, the Li content should be 5 wt% to achieve increased combustion intensity compared to Mg powders. When Mg-Li alloys and Mg powders were composited with polytetrafluorethylene (PTFE) serving as an oxidizer, the burn rates of MgLi3/PTFE and MgLi5/PTFE were ∼7.1 and 12.1 m/s, respectively, which were ∼1.8 and 6.8 m/s higher than that of Mg/PTFE. The flame temperature of Mg-Li/PTFE (∼1537–1552℃) of 3–5 µm was slightly lower than that of Mg/PTFE (∼1637℃). Therefore, the prepared Mg-Li alloys are promising candidates for use as fuels for energetic materials.

Microstructure Evolution and Strengthening Mechanism of Dual-Phase Mg-8.3Li-3.1Al-1.09Si Alloys during Warm Rolling.

In this study, the rolling process of the warm-rolled duplex-phase Mg-8.3Li-3.1Al-1.09Si alloy and the strengthening mechanism of as-rolled Mg-Li alloy were investigated. The highest ultimate tensile strength (UTS, 323.66 ± 19.89 MPa) could be obtained using a three-pass rolling process with a 30% thickness reduction for each pass at 553 K. The strength of the as-rolled LAS831 alloy is determined by a combination of second-phase strengthening, grain refinement strengthening, dislocation strengthening, and load-transfer reinforcement. Of these factors, dislocation strengthening, which is caused by strain hardening of the α-Mg phase, can produce a good strengthening effect but also cause a decrease in plasticity. The Mg2Si phase is broken up into particles or strips during the rolling process. After three passes, the AlLi particles were transformed into an AlLi phase, and the Mg2Si particles and nanosized AlLi particles strengthened the second phase to form a hard phase. The average size of the DRXed β-Li grains decreased with each successive rolling pass, and the average size of recrystallized grains in the three-pass-rolled LAS831 alloy became as low as 0.27 μm. The interface between the strip-like Mg2Si phase and the α-Mg phase is characterized by semicoherent bonding, which can promote the transfer of tensile and shear forces from the matrix to the strip-like Mg2Si phase, thereby improving the strength of the matrix and thus strengthening the LAS831 alloy.