Alloy Layer Research Articles

Sustainable Dual‐Layered Interface for Long‐Lasting Stabilization of Lithium Metal Anodes

AbstractLithium metal anodes (LMAs) offer substantial promise for high‐energy‐density rechargeable batteries, but managing the complex electrolyte–anode interface is a challenge. Herein, a sustainable dual‐layered interface (SDI) protected Li anode is developed using a joint electrospinning‐rolling technique. In this SDI, polyacrylonitrile (PAN) nanofibers normalize Li‐ion flux across the bulk electrolyte and mitigate electrode volume expansion. More significantly, the continuous release of lithiophilic metal ions aids in constructing alloy interphase in situ, which facilitates Li‐ion transport and uniform lithium deposition. With the dynamic protection of SDI films, cracks in the alloy layer can be promptly repaired during cycling, ensuring efficient control of the electrolyte–anode interface and prolonged stabilization of LMAs. As validation, using a PAN/SnCl2 film as an SDI prototype, the symmetric cells achieve ultra‐long cycling of 5200 h (≈7 months) at 5 mA cm−2 and 5 mAh cm−2. When paired with a sulfur cathode (in ether electrolyte) or a LiNi0.8Co0.1Mn0.1O2 cathode (in ester electrolyte), the full cells exhibit exceptional stability and rate performance. This sustainable protection strategy for LMAs opens a path to suppress dendrite growth, creating new opportunities for advanced lithium metal batteries.

Surface microstructural alterations and grain refinement mechanisms of tungsten heavy alloys by thermo-mechanical coupling: A laser-assisted milling case

Ultrafine-grained (UFG) tungsten heavy alloys possess potential applications in precision instruments and nuclear protection. In the present study, a comprehensive investigation of machined surface microstructural alterations and grain refinement mechanisms in laser-assisted milling (LAM) 95W-3.5Fe-1.5Ni alloy was demonstrated by recognizing its surface microstructures and mechanical properties under different combinations of the laser power and cutting depth. Graded microstructural characteristics along the surface degenerating layer and subsurface deformed layer of tungsten heavy alloy were identified for the first time, dramatically changing from workpiece bulk. Results showed that the adaptability between the thickness of the laser heat-affected layer and the depth of cut greatly influenced surface recrystallization layer microstructures regarding the thermal-mechanical coupling effect. An ordered, continuous, and equiaxed refined grains distribution layer was recognized when a particular machining condition was adopted, resulting in a substantial improvement of mechanical hardness. It could be indicated that a redundant heat-affected area would induce strain accumulation and promote recrystallization in LAM. Moreover, a dislocation density-based recrystallization model was applied to complement the experimental results considering the temporal transformation of grain refinement and recovery phenomena. Clarifying the above aspects is crucial to control the tungsten heavy alloys' surface microstructures and service performance during high-performance machining operations.

Effect of yttrium on the formation, microstructure and high-temperature oxidation resistance of the oxide film on the surface of FeCr alloy

Yttrium was diffused into the surface layer of FeCr alloy using an electrodeposition–thermal method via yttrium nitrate solution and diffusion annealing at 1000 °C. Y-doped FeCr samples exhibited excellent high-temperature oxidation resistance. The mass gains and spallation of Y-doped FeCr samples were only 0.51–0.64 mg/cm2 and 0.19–0.25 mg/cm2, respectively, and much lower than the alloy without yttrium (20.7 mg/cm2 and 9.08 mg/cm2, respectively) when oxidized in air at 900 °C for 200 h. The presence of yttrium increased the number of oxide nucleation sites, led to the transformation of the oxide from the Cr2O3 phase to the spinel (FeCrY)3O4 phase and accelerated the rapid formation of a continuous oxide film in the initial oxidation stage. The yttrium content affected the formation and microstructure of oxide film due to the lattice distortion of the FeCr phase. Excess Y induced formation of Y2O3 at grain boundaries, which further increased the bonding force between the oxide film and the substrate. A first-principles calculation confirmed that the bond strength between Y and other atoms was improved significantly. The length of the CrY bond showed little change under an external stress, which increased the bonding strength of the FeCr/Cr2O3 interface.

Study on removal of recast layer of NiTi shape memory alloy machined with magnetic field-assisted WEDM-ECM complex process

Study on removal of recast layer of NiTi shape memory alloy machined with magnetic field-assisted WEDM-ECM complex process

ZnO@C Coated Cellulose-Based Separators Control Lithium Deposition Direction to Stable Lithium Metal Batteries.

Li metal anodes have attracted attention due to their high specific capacity and low electrochemical potential. Nevertheless, the uncontrolled growth of Li dendrites hinders the practical application of Li metal batteries. Although the various approaches have made performance improvements, safety hazards still exist since Li dendrites are still growing along the anode to the separator during the continuous plating/stripping process. Herein, a straightforward method is proposed to achieve stable Li metal batteries with directional growth control by using a functional ZnO@C/cellulose membrane as a separator. The abundant pore structure and functional groups of biomass cellulose enhance the Li-ion transport and interface compatibility. The ZnO transforms in situ to form a Li-Zn alloy layer which is uniformly coated to the separator to direct uniform ion concentration polarization and charge distribution polarization, control the growth direction of Li, significantly improve the cycling stability, and promote the reversibility of the Li plating/exfoliation process. As a result, the symmetric cell exhibits an extreme lifetime of more than 4500h and low polarization at 3mAcm-2 . The cycling performance of the Li||LiFePO4 full cell reaches a capacity retention of 98% after 270 cycles at a mass loading of 10mgcm-2 .

Effect of atomized hybrid nanofluid on machined subsurface layer of nickel alloy

Nickel-based alloys have encountered microstructural changes during machining, which forces machining industries to use cutting fluid excessively. The progress of sustainable methods for machining operations is necessary due to their adverse effect on the environment, operator health, and manufacturing economics. In the present research, the application of an Ultrasonically Atomized Hybrid Nanofluid (UAHNF), a near-dry lubrication technique, has been utilized for performing machining of nickel alloy, and its impact on the machined subsurface layer has been examined. The machining-affected subsurface has been analyzed for plastic strain and microstructural analysis using XRD and EBSD techniques. It has been found that the UAHNF method provides lesser plastic strain and better microstructural evolution than dry cutting. Moreover, it uses a little cutting fluid and is an environmentally benign and economical process.

Physics of the Effect of High-Temperature Pulse Heating On Defects in the Surface Layer of a Metal Alloy

Physics of the Effect of High-Temperature Pulse Heating On Defects in the Surface Layer of a Metal Alloy

Understanding the corrosion of Mg alloys in in vitro urinary tract conditions: A step forward towards a biodegradable metallic ureteral stent

Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as ureteral stent materials have emerged as a promising strategy, mainly due to the improved radial force and slower degradation rate expected. Therefore, this study aimed to characterize different biodegradable metals in urinary tract environment to understand their propensity for future utilization as base materials for ureteral stents. The corrosion of 5 Mg alloys – AZ31, Mg-1Zn, Mg-1Y, pure Mg, and Mg-4Ag – under simulated urinary tract conditions was accessed. The corrosion layer of the different alloys presented common elements, such as Mg(OH)2, MgO, and phosphate-containing products, but slight variations in their chemical compositions were detected. The corrosion rate of the different metals varied, which was expected given the differences in the corrosion layers. On top of this, the findings of this study highlighted the significant differences in the samples' corrosion and corrosion layers when in stagnant and flowing conditions. With the results of this study, we concluded that Mg-1Zn and Mg-4Ag presented a higher propensity for localized corrosion, probably due to a less protective corrosion layer; Mg-4Ag corroded faster than all the other four alloys, and Mg-1Y stood out due to its distinct corrosion pattern, that showed to be more homogeneous than all the other four samples, making this one more attractive for the future studies on biodegradable metals.

Wear performance of composite dual-layer coated Al-12Si alloy: Effect of Al2Ce reinforcement and micro-arc oxidation

An attempt has been made to enhance the wear resistance of Al-12Si alloy by forming a dual-layer coating consisting of an Al-12Si matrix composite layer (Al-12Si + ∼40 vol % Al2Ce) and an external composite oxide layer. While the hardness of monolithic Al-12Si alloy was ∼110 HV, the Al-12Si matrix composite layer has got hardness of ∼140 HV and exhibited ∼6 times higher sliding wear resistance due to the suppression of the plasticity-induced adhesive wear by Al2Ce particles. Applying micro-arc oxidation (MAO) as a post-treatment favoured an oxide layer (Al2O3) on the Al-12Si alloy and a composite oxide layer (CeO2 + Al2O3) on the Al-12Si matrix composite layer. The MAO coatings fabricated on the Al-12Si alloy and Al-12Si matrix composite layer, with hardness of ∼11 GPa and ∼13 GPa, respectively, provided more than two orders of magnitude increase in the wear resistance by shifting the wear mode to elasticity-dominated wear. However, the critical load imposing the complete detachment of the MAO coating by intense cracking and spallation during testing was determined as 3 N for the MAO'ed Al-12Si alloy and 5 N for the MAO'ed Al-12Si matrix composite layer. The wear resistance of the MAO coating of the Al-12Si matrix composite layer was ∼2 times higher than that of the MAO coating of the Al-12Si alloy below the critical test loads, where the coatings remain intact with the substrate.

Effects of Structural Radiation Disorder in the Near-Surface Layer of Alloys Based on NbTiVZr Compounds Depending on the Variation of Alloy Components

This research investigated how changes in the composition of Nb–Ti–V–Zr-based alloys affect their resistance to radiation damage and the preservation of strength characteristics when exposed to the heavy ions Kr15+ and Xe23+. These heavy ions simulate the impact of nuclear fuel fission fragments on the material. The primary objective of this study was to explore how variations in alloy components influence radiation resistance and the retention of alloy strength properties. Accumulation of radiation defects can potentially lead to embrittlement and a decrease in resistance to external factors during operation. An analysis of the X-ray diffraction data obtained from the initial alloy samples, in relation to the variations in the number of components, revealed that an increase in the number of components leads to the formation of a denser crystal structure. Additionally, this resulted in the emergence of a dislocation strengthening factor associated with changes in crystallite size. Concurrently, when assessing changes in the strength characteristics of the irradiated alloys, it was observed that the NbTiV and NbTiVZr alloys demonstrated the highest resistance to strength property degradation, specifically a 2.5- to 5-fold increase in resistance against a significant decrease in hardness. It was confirmed that the significant factor contributing towards the enhancement and preservation of the structural and strength properties is the dislocation strengthening mechanism. An increase in dislocation strengthening effectively enhances resistance against destructive embrittlement, particularly when exposed to high-dose irradiation.

Infrared dielectric function of GaAs1−xPx semiconductor alloys near the reststrahlen bands

The infrared dielectric function of thick GaAs1−xPx alloy layers grown on (001) GaAs substrates by hydride vapor phase epitaxy was investigated in the reststrahlen region using Fourier-transform infrared ellipsometry. The spectra are influenced by the Berreman artifact at the longitudinal optical phonon frequency of the GaAs substrate and by interference fringes due to the finite layer thickness. The ellipsometric angles were analyzed to determine the dielectric function of the alloy layer. Two-mode behavior, including strong GaAs-like and GaP-like optical phonons, was observed, confirming the results of Verleur and Barker [Phys. Rev. 149, 715 (1966)]. Due to the increased sensitivity of ellipsometry in the reststrahlen region, several weak phonon features could also be seen. The lattice absorption peaks are asymmetric and show side bands at the lower and higher frequencies. A single additional peak, as suggested by the percolation model, does not describe the spectra. The cluster model proposed by Verleur and Barker is a better fit to the data. Due to the broadening of the phonon absorption peaks, the authors were unable to find a unique decomposition into multiple components.

Influence of Shell Thickness on the Photophysical Properties of Core—Shell Perovskite Nanocrystals

AbstractCore–shell perovskite nanocrystals (NCs) have emerged as a promising class of materials for optoelectronic applications due to their unique properties and stability. Although much research has been conducted on the shell growth mechanism and properties of the core–shell NCs, little is known about the role of shell thickness in determining their optical properties. Herein, a heteroepitaxial method is employed to prepare a series of core–shell FAPbBr3/CsPbBr3 NCs with different shell thicknesses. Through temperature‐dependent photoluminescence measurement, it is found that the electronic structure of core–shell FAPbBr3/CsPbBr3 NCs evolves from quasi‐type‐II to type‐I with the increase in shell thickness. This abnormal transition can be attributed to the thickened gradient alloy layer FA1‐xCsxPbBr3, which effectively relieves the lattice mismatch and releases strain in the NCs, resulting in variations in the bandgap between the core and the shell. Furthermore, the biexciton Auger lifetimes in these samples exhibit a non‐monotonic dependence on shell thickness, indicating the electronic structure transition. These results provide valuable insights into the relationship between shell thickness, electronic structure, and optical properties in core–shell perovskite NCs, which may offer guidance for the design of high‐performance optoelectronic devices.

Assessing Li accommodation at amorphous ZrO2 grain boundaries

Nuclear Pressurised Water Reactors (PWRs) use zirconium alloys as a fuel cladding, preventing the cooling water, at elevated pH using lithium hydroxide, from interacting with the fuel. Boron, as boric acid, is added to the coolant as a reactivity shim. Future reactor designs are considering removing soluble boron reactivity control to aid plant simplification. The presence of lithium in the absence of boron in the coolant has, however, been found to accelerate the corrosion of zirconium-based alloys under certain conditions and the mechanisms by which this occurs is under investigation. The ingress of lithium into the bulk oxide layer of zirconium alloy has been addressed in a previous study and was found to be unlikely. Here, atomistic simulations were used to produce Brouwer diagrams from which the solubility of lithium in amorphous structures representing complex grain boundaries have been predicted. The solubility of lithium in these amorphous structures is predicted to be high and will produce an elevated concentration of oxygen defects within the amorphous structure. This could offer a mode for transport of oxygen to the metal oxide interface and, potentially, offer a mechanism or part of a mechanism for observed lithium-accelerated corrosion of Zr-based alloys.

Surface Characterization, Mechanical Properties, and Corrosion Behavior of Zn-Ni Alloy Coated Steel Using Electroplating-Hot-Dip Galvanizing

In this study, the processing of zinc-nickel alloys with an electroplated nickel layer as the first layer followed by hot-dip galvanizing on plain carbon steel (St37) is investigated. The effect of the nickel layer and the effect of the immersion time on the alloy layers of the coating obtained by this method are studied. In addition, some properties of the obtained coating, such as the overall thickness, hardness, surface uniformity, coating adhesion strength, and corrosion resistance, were investigated using the optical microscope, scanning electron microscopy, energy dispersive x-ray spectrometer analysis, and potentiostat. The results show that the 16-min immersion time is the optimum galvanizing time at which an alloy with a nickel content of 0.11 wt% is formed and that the overall thickness of the galvanized sheet, especially the alloy layers, decreases compared to the pure zinc sheet. In addition, a more ductile, corrosion-resistant, and smoother surface is obtained.

Interaction of Gallium with a Copper Surface: Surface Alloying and Formation of Ordered Structures.

Alloys of gallium with transition metals have recently received considerable attention for their applications in microelectronics and catalysis. Here, we investigated the initial stages of the Ga-Cu alloy formation on Cu(111) and Cu(001) surfaces using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). The results show that Ga atoms deposited using physical vapor deposition readily intermix with the Cu surface, leading to a random distribution of the Ga and Cu atoms within the surface layer, on both terraces and monolayer-thick islands formed thereon. However, as the Ga coverage increases, several ordered structures are formed. The (√3×√3)R30° structure is found to be thermodynamically most stable on Cu(111). This structure remains after vacuum annealing at 600 K, independent of the initial Ga coverage (varied between 0.5 and 3 monolayers), indicating a self-limited growth of the Ga-Cu alloy layer, with the rest of the Ga atoms migrating into the Cu crystal. For Ga deposited on Cu(001), we observed a (1 × 5)-reconstructed surface, which has never been observed for surface alloys on Cu(001). The experimental findings were rationalized on the basis of density functional theory (DFT) calculations, which provided structural models for the most stable surface Ga-Cu alloys on Cu(111) and Cu(001). The study sheds light on the complex interaction of Ga with transition metal surfaces and the interfaces formed thereon that will aid in a better understanding of surface alloying and chemical reactions on the Ga-based alloys.

Technology of forming a wear-resistant thermite alloy layer based on the Fe-Cr-C system by self-propagating high-temperature synthesis

The technology of forming a thermite alloy layer on the basis of Fe-Cr-C system on a metal basis by self-propagating high-temperature synthesis is offered, which allows to obtain cast functionallayers withphysico-mechanical and exploitativeproperties. The optimal technological parameters of the forming a wear-resistant layer of thermite alloy process are determined: the amount of metal filler with the maximum yield of suitable alloy, the heating temperature of the thermite charge and the mold to obtain additional heat, the temperature ranges of the melt to melt the metal base with further formation of the functional layer. Metallographic studies of the obtained wear-resistant layer of thermite allo[y showed that the zone of formation of the functional layer is characterized by the stability of the macrostructure and the positive effect of non-metallic inclusions in the form of Al2O3, which influences the formation of chromium carbides in the obtained alloy by creating the effect of inoculative modification of thermite alloy.

Morphological investigation and electrochemical performance evaluation of novel porous Ni–Pt produced by Al-deposition/dissolution in molten salts for hydrogen and oxygen evolution reaction

A two-step electrolytic deposition of Ni and Pt from aqueous solutions formed a porous Ni–Pt alloy surface. A nickel sample with a thin layer of platinum covered by a nickel electrode coating was used in the electrolysis of aluminium from molten salts at 900°. The molten salt was a mixture of 48.25 mol% NaCl, 48.25 mol% KCl and 3.5 mol% AlF3. Deposition of Al on Ni and Pt samples was carried out at a potential of −1.8 V, respectively. Al and the resulting intermetallic phases were dissolved at −0.5 V to produce porous Ni–Pt alloy foams. It was found that a porous Ni–Pt alloy layer is formed due to an intense reaction between liquid Al and solid Ni, which propagates deep into the solid material. The high temperature of the molten salts allows the metallic Pt to penetrate deep into the porous structure. It makes it possible to obtain a uniform Pt distribution in the electrode volume. The fabricated porous Ni–Pt alloy was tested in cathodic and anodic polarisation measurements in an aqueous solution of 10 wt% KOH to assess their electrocatalytic activity. During constant-voltage electrolysis, a solid-electrolyte hydrogen sensor was coupled to the experimental system and allowed the in-situ hydrogen production efficiency to be measured. The promising electrochemical performance of porous Ni–Pt alloys as electrode materials for hydrogen and oxygen release in alkaline solutions was confirmed by measuring the partial pressure of hydrogen in electrolysis at constant voltage. Due to the large amount of highly active surface area, the porous Ni–Pt alloys showed a significantly higher current density than untreated samples in hydrogen evolution reactions. Based on cyclic voltammetry measurements, it was demonstrated that the electrochemically active surface area was highest for the modified Ni–Pt electrode. The Pt-modified sample with Al deposition at −1.8 V and a molten salt temperature of 900 °C generated the highest amount of hydrogen (9.38 mL).

Magnetic interactions and high-field magnetotransport properties of Ge1-x-ySnxMnyTe epitaxial layers

In this work, we present the structural, magnetic and magnetotransport results of Ge1−x−ySnxMnyTe thin layers with x = 0.076–0.22 and y = 0.051–0.16. The samples were grown via molecular beam epitaxy with thickness ranging from 160 nm to 900 nm. From X-ray diffraction analysis, the layers maintain low symmetry rhombohedral crystal structure inherited from the host lattice. The rhombohedral distortion is well-maintained in alloyed layers even in the sample with the highest Sn and Mn contents, x ≈ 0.22 and y ≈ 0.051. The dc magnetic susceptibility, χdc(T) of all three layers manifests large bifurcation in the field-cooled/zero-field-cooled curves which might represent frustrated magnetic state interpreted as possible cluster-glass order. From high field magnetotransport results, a negative to positive crossover in magnetoresistance is observed for y = 0.11 at T ≈ 36 K. Furthermore, we also present a modified scaling results of anomalous Hall resistivity which displays a large magnitude, ρAH ≈ 4.9 μΩcm at T = 4.2 K for the layer with y = 0.11. The scaling results show that both skew scattering and side-jump mechanisms contribute to the anomalous Hall effect in Ge1−x−ySnxMnyTe samples however; the later seems to be dominant driving mechanism.

Healable Anti-Corrosive and Wear-Resistant Silicone-Oil-Impregnated Porous Oxide Layer of Aluminum Alloy by Plasma Electrolytic Oxidation.

Lubricant (or oil)-impregnated porous surface has been considered as a promising surface treatment to realize multifunctionality. In this study, silicone oil was impregnated into a hard porous oxide layer created by the plasma electrolytic oxidation (PEO) of aluminum (Al) alloys. The monolayer of polydimethylsiloxane (PDMS) from silicone oil is formed on a porous oxide layer; thus, a water-repellent slippery oil-impregnated surface is realized on Al alloy, showing a low contact angle hysteresis of less than 5°. This water repellency significantly enhanced the corrosion resistance by more than four orders of magnitude compared to that of the PEO-treated Al alloy without silicone oil impregnation. The silicone oil within the porous oxide layer also provides a lubricating effect to improve wear resistance by reducing friction coefficients from ~0.6 to ~0.1. In addition, because the PDMS monolayer can be restored by frictional heat, the water-repellent surface is tolerant to physical damage to the oxide surface. Hence, the results of this fundamental study provide a new approach for the post-treatment of PEO for Al alloys.

Failure analysis of convection section tube in an ethylene cracking furnace due to metal dusting

To study the failure in the convection section tubes of an ethylene cracking furnace, macroscopic inspections, chemical composition analysis, metallographic microscopy, hardness testing, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis are performed. The experiments confirmed the reason for metal dusting occurrence of 304H austenitic stainless steel that the inner wall Cr2O3 protective film was destroyed by overheating. There were dense circular corrosion pits on the fire side inside the furnace tubes, loose metal oxides and carbide particles were filled in the corrosive pits. Severe carburization occurred on the surface of the pits, the furnace tube experienced metal dusting. The metal dusting resulted in the decomposition of the surface layer of the metal alloy into metal particles and graphite to thin the wall thickness. Then the furnace tube cracked because of the stress concentration appeared in the furnace tube with reduced wall thickness. Finally, some suggestions and countermeasures on the failure of metal dusting of the furnace tube were proposed.