Alloy Layer Research Articles

Defects-Abundant Ga2 O3 Nanobricks Enabled Multifunctional Solid Polymer Electrolyte for Superior Lithium-Metal Batteries.

Polyethylene oxide (PEO)-based polymer electrolytes with good flexibility and viscoelasticity, low interfacial resistance, and fabricating cost have caught worldwide attention, but their practical application is still hampered by the instability at high voltages and the low ionic conductivity (10-8 to 10-6 S cm-1 ). Herein, we rationally designed defects-abundant Ga2 O3 nanobricks as multifunctional fillers and constructed a PEO-based organic-inorganic electrolyte for lithium metal batteries. Due to the abundant O-defects feature of Ga2 O3 filler, this PEO-based composite electrolyte not only broadens electrochemical stability window (over 5.3 V versus Li/Li+ ) but also in situ forms a Li-Ga alloy and solid electrolyte interphase (SEI) film during the cycling process causing a rapid diffusion of Li+ ions. The as-prepared electrolyte has good interface compatibility with Li metal (without short-circuiting over 500 h at 0.2 mA cm-2 ) and possesses superior high ionic conductivity. The assembled all-solid-state LiFePO4 //Li cells attained an excellent cycling performance of 146 mAh g-1 over 100 cycles at 0.5 C. The XPS analysis reveals that Ga2 O3 nanobricks can form in situ a Li-Ga alloy layer at the polymer/anode interface. This work shed a light on designing high ionic conductivity lithium alloys in the composite electrolyte, which can improve the electrochemical properties of PEO-based polymer electrolytes.

Synthesis of Different Nano‐layer Shells (Mono‐, Bi‐, and Alloy Layers)‐Coated Gold Spherical Nanoparticles Core for Catalysis

AbstractVarious types of metal layer shells such as mono‐, bi‐, and alloy layer using gold and silver on preformed gold spherical nanoparticles core were synthesizing using sodium borohydride as reducing agent. UV‐vis absorption spectroscopy, transmission electron microscopy images, and X‐ray diffraction techniques were used to characterize the prepared pristine gold spherical nanoparticles and various core‐shell metal nanoparticles. High‐angle annular dark field scanning transmission electron microscopy‐energy dispersive X‐ray spectroscopy mapping images were recorded for the alloy and bilayer shell coated core‐shell nanoparticles. Catalytic reduction of 4‐nitroaniline in the presence of sodium borohydride was taken to study the catalytic activity of the prepared core‐shell nanostructures. Interestingly, the alloy shell coated gold spherical nanoparticles (AuNP@AgAu) showed the best catalytic activity (higher rate constant; 21.61×10−3 s−1) than that of mono‐, and bilayer core‐shell and pristine gold spherical nanoparticles.

Synthesis of core/shell nanocrystals with ordered intermetallic single-atom alloy layers for nitrate electroreduction to ammonia

Synthesis of core/shell nanocrystals with ordered intermetallic single-atom alloy layers for nitrate electroreduction to ammonia

NiO/β-(AlxGa1−x)2O3/Ga2O3 heterojunction lateral rectifiers with reverse breakdown voltage >7 kV

NiO/β-(AlxGa1−x)2O3/Ga2O3 heterojunction lateral geometry rectifiers with diameter 50–100 μm exhibited maximum reverse breakdown voltages >7 kV, showing the advantage of increasing the bandgap using the β-(AlxGa1−x)2O3 alloy. This Si-doped alloy layer was grown by metal organic chemical vapor deposition with an Al composition of ∼21%. On-state resistances were in the range of 50–2180 Ω cm2, leading to power figures-of-merit up to 0.72 MW cm−2. The forward turn-on voltage was in the range of 2.3–2.5 V, with maximum on/off ratios >700 when switching from 5 V forward to reverse biases up to −100 V. Transmission line measurements showed the specific contact resistance was 0.12 Ω cm2. The breakdown voltage is among the highest reported for any lateral geometry Ga2O3-based rectifier.

Modification of the Properties of the Surface Layers of Aluminum Alloys under the Action of a High-Power Ion Beam

Modification of the Properties of the Surface Layers of Aluminum Alloys under the Action of a High-Power Ion Beam

Assessing residual stresses in the surface layer of the ZK60 alloy after an exposure to corrosion solution

Magnesium alloys preliminary immersed in a corrosion solution suffer from embrittlement, referred to as pre-exposure stress corrosion cracking (PESCC). It was suggested that PESCC can be attributed to the corrosion product film-induced stress (CPFIS), which is known to be responsible for SCC in many alloys. However, the internal stress associated with the formation of the corrosion products (CP) layer on Mg alloys have not been investigated as yet. Thus, in the present study, the internal residual stresses of the first and second kinds were assessed in the alloy ZK60 exposed to the corrosion solution, using the deflection of the thin plate and by the X-ray diffraction technique, respectively. It is found that the deposition of CP on the surface of the alloy ZK60 creates the compressive internal stresses of both kinds — I and II. The macro residual stress of the kind I in the thin plate is found to be not exceeding 3 MPa, while the micro residual stress of the second type in the surface layer of 20 – 30 µm can be as high as 290 MPa and cause plastic deformation of the bare metal with the internal stress which cannot be relieved by the removal of CP.

Crystal Structure and Properties of Zinc Phosphate Layers on Aluminum and Steel Alloy Surfaces

Many studies have been carried out on the phosphating of steel and aluminum alloys used in automotive engineering, but characterization of the properties of the phosphate layers formed by the co-phosphating of these alloys in the presence of different base metals is still lacking. In this study, the crystal structure and properties of the phosphate conversion layers formed on the surface of the aluminum alloys important in vehicle manufacturing (cast and forged AlSi1MgMn, and AA6014 panel) and the CRS SAE 1008/1010 reference steel plate by co-deposition prior to painting were investigated. On a process line set up for the phosphating of typical iron and steel alloys, the phosphate coating was formed using nitrite and nitroguanidine accelerators under identical technological parameters. The microstructure of the formed phosphate layers was examined using scanning electron microscopy (SEM), its phase composition using X-ray diffraction (XRD), and its elemental composition using energy-dispersive X-ray analysis (EDX). The suggested main crystalline phase (Zn2.3(Ni0.1Mn0.6)(PO4)2·4H2O) in the surface phosphate layer of both aluminum alloys studied was similar to hopeite, whereas in the steel plate, a minor hopeite phase were identified in addition to the main crystalline phosphophyllite phase (~95%). It can be concluded that, during the combined phosphating treatments, the surfaces of different aluminum and steel alloys behaved similarly to the individual treatments and did not impede the coating reactions of the other metal. To obtain an adequate coating of aluminum and steel alloys, fluoride should always be present in the production line. Comparing the effects of accelerators, we found that the use of nitrite accelerator with the same amount of fluoride resulted in a higher coverage and better quality of the surface protective layer of the aluminum alloys. However, for the steel plate, there was no significant difference between the phosphate coatings prepared with the two different accelerators.

Effects of Zinc alloy layer on corrosion and service life of galvanized reinforcing steels in chloride-contaminated concrete

Corrosion of reinforcing steel affects the service life of structures. A chloride environment exposed to reinforced concrete structures accelerates the corrosion process. Hot-dipped galvanized steel was used as reinforcing steel instead of bare carbon steel to provide better protection against corrosion. The coating layers of galvanized steel have different compositions which can affect corrosion behavior. When galvanized steel has been corroded, it will expose the zinc-alloy layer that has a different composition than the top pure zinc layer. A comparative study on electrochemical properties such as concrete resistivity, polarization resistance, corrosion current density, anodic Tafel slope, cathodic Tafel slope, and corrosion rate of bare carbon steel (BS), galvanized steel (GS), and corroded galvanized steel (CGS) was conducted. The BS, GS, and CGS were embedded in concrete with different mix proportions by varying water-to-binder ratios, chloride contents, and types of binder. The electrochemical properties data were measured by the Wenner four-probe, linear polarization resistance (LPR), and potentiodynamic polarization resistance (PPR) tests. The measurement results show that the resistivity of 0.4 w/b concrete is higher than 0.6 w/b concrete. Corroded galvanized steel's polarization resistance is lower than bare carbon steel's and galvanized steel's. The corrosion rate calculated from the Stern-Geary equation of corroded galvanized steel is higher than bare carbon steel and galvanized steel. Based on the calculation results, the specimens with galvanized steel have a longer crack-initiating life than the bare carbon steel. The crack-initiating life of the reinforced concrete structures using galvanized steel can be more precisely predicted by considering the corroded galvanized layer.

Polyacrylonitrile fibers network reinforced polymer electrolyte with Li-Sn alloy layer protected Li anode toward ultra-long cycle lifespan for room-temperature solid-state batteries

Poly(ethylene oxide) polymer electrolyte composited with high content of succinonitrile organic plasticizer has excellent ionic conductivity at room temperature. Unfortunately, the poor interface stability between this novel solid polymer electrolyte (SPE) and Li metal anode leads to limited cycling performance, which seriously hinders its commercial applications. Herein, the electrospun nanofibers framework of polyacrynitrile (PAN) is introduced as a three-dimensional polymer filler, which can not only provide a robust skeleton for improved mechanical stability, but also inhibit the growth of Li dendrites with increased Li ion transference number from 0.28 to 0.41. Meanwhile, the Li anode is modified via constructing a dense Li-Sn alloy layer, offering a perfectly passivated anode surface and eliminating the side reaction between metallic Li and SPE efficiently. Hence, the interface compatibility and structure stability between the anode and the polymer electrolyte are greatly improved in the prolongated cyclic testing due to the synergistic effect of PAN reinforced SPE and Li-Sn alloy layer coated Li. As a result, the symmetrical battery can cycle stably for 2400 h at 25 °C under 0.1 mA cm−2 and 0.1 mAh cm−2, while the LiFePO4 based full battery can keep a good capacity retention of 85 % even after 500 cycles at 0.5 C. This work demonstrates that the combination of modifying SPE and building advanced interface layer on the Li anode is an effective measure to optimize the room temperature cycling performance of polymer solid-state Li battery.

Effects of Specimen Thickness and Non-Isothermal Process on Creep Behavior of AA2024 Aluminum Alloy

Fiber metal laminate (FML) is a kind of lightweight material that has garnered much attention in recent years due to its excellent properties under tensile, flexure, and impact conditions. However, little attention has been paid to the evolution of aluminum alloy during the FML forming process. In this paper, the effects of specimen thickness and the non-isothermal process on creep behavior of AA2024 aluminum alloy, which is generally used in FMLs, were systematically studied in terms of creep strain, mechanical properties, and microstructure. The results show that the microstructure and mechanical properties of the aluminum alloy layer are greatly affected by the creep age during the FML forming process, but the specimen thickness has little effect on the creep behavior under experimental conditions. During the non-isothermal process, the creep strain generated during the heating stage is about 40% of total strain. Compared with the isothermal process, the creep strain of the non-isothermal process increases by 20–40%, and the apparent activation energy Qc is larger. According to the creep behavior of AA2024 aluminum alloy during the non-isothermal process, a creep constitutive model was established to accurately simulate the deformation of FMLs.

Investigation on hybrid bonding of tungsten/steel with in-situ formed composites interlayer

Hybrid bonding between steel and W using 88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures sandwiched between Ni and Cu foils was carried out in vacuum for 60 min at 1120 ℃ with a pressure of 5 MPa. The assembly sequence of bonding specimens was steel/Ni/Cu/88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures/Cu/Ni/Cu/W. The microstructures and composition distribution of the joint were studied by SEM and EDS. Joint properties were evaluated by shear experiment tests, and the fracture characteristics of the shear samples for the joints were also determined by SEM. The results showed that the joints comprised steel/Ni/composites/Cu-Ni/W, wherein the composites interlayer consisting of tungsten heavy alloy and irregular Ni agglomerate in-situ formed by the combined sintering of 88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures. The hybrid bonding mechanisms of the interfaces in the joint include solid-phase diffusion bonding and transient liquid phase diffusion bonding. An additional hot-dip experiment found that obvious solid-liquid interface diffusion and Ni segregation occurred under the bonding conditions, and a large number of W atoms diffused into the Cu-Ni liquid phase. In the Cu-Ni alloy layer, the content of element W is more than 4.22% (at.%). The average shear strength of W/steel joints was 263 ± 7 MPa and all the shear samples were fractured in the W near the bonding interface.

A new type of gradient structure FeCoCrNiWMo high entropy alloy layer by plasma solid-state surface metallurgy

In this paper, the FeCoCrNiWMo HEA layer with metallurgical bonding and gradient structure was successfully prepared by plasma solid-state surface metallurgy for the first time. The microstructure, composition, growth and deposition kinetics of HEA layer was studied by XRD, SEM and EDS. The results show that the FeCoCrNiWMo HEA layer consists of HCP and FCC phase. In the equipotential mode, the high vacancy concentration gradient layer can't be formed continuously on the substrate surface. In addition, the serious lattice distortion and the increase of atomic packing density caused by different atomic sizes decrease the density of vacancy formation. So the composite strengthening layer structure of HEA layer (deposit layer + diffusion layer) is formed on the substrate surface instead of conventional alloying layer. According to Boltzmann's hypothesis, the entropy value of calculating the surface mixing entropy of HEA layer is >1.5 R, which accords with the definition of high-entropy alloy. Compared with the substrate, the wear resistance and high-temperature oxidation resistance of the HEA layers are improved to some extent and the wear mechanism of substrate and HEA layers is mainly abrasive wear, which is accompanied by adhesive wear and oxidation wear. The results show that it is reasonable and feasible to prepare a new type metallurgical bonding and gradient structure of wear resistant and high-temperature oxidation resistant HEA layer by plasma solid-state surface metallurgy.

A courtly brocade belt belonging to Qajar period (1789–1925), Iran

This paper identifies the materials used to make a brocade belt belonging to the Qajar courtiers in Iran. This belt consists of two fabric types: red support and golden brocade. Accordingly, this paper examined the skin and tannin type, fiber types, dyeing agents, mordant, and metal wrapping of brocade yarns and metal buckle. Technical imaging, ESI–MS, FORS, FTIR and SEM–EDS were used to identify the materials. Multi-band imaging methods included Vis, UVL, IRR, and UVR, in which UVFC and IRFC images were obtained after processing. The results showed that cotton yarn was used in both fabrics. The red fabric yarns were dyed using cochineal and alum mordant. Also, the yellow brocade yarns were dyed using catechins-rich plants, and in this dyeing process, polyphenols and alum have been as mordant. Madder-dyed yarns are also found in parts of the belt. Examination of the metal wrapping of brocade yarns suggests using strips of copper-nickel alloy with a thin layer of gold-silver alloy. This secondary coating protects the copper-nickel strips and increases their golden luster. The leather analysis of the leather parts also indicated the using cattle/calfskin tanned with gallotannins. Belt buckle analysis also shows the use of brass alloy with a high percentage of zinc, leading to a golden sheen and the buckle desired strength. The results show the use of low-cost materials in the manufacture of clothing for the lower levels of the Qajar court.

Fabrication of AlZn4SiPb/Steel Clad Sheets by Roll Bonding: Their Microstructure and Mechanical Properties

An AlZn4SiPb/steel clad composite was prepared via roll bonding at room temperature. The influence of solution and aging treatment on the structure and performance of the clad composite was investigated. The results show that the Al/steel clad composites exhibited satisfactory interfacial adhesion. Pb of the aged Al matrix was spheroidized and uniformly dispersed. An uneven interfacial transition area with a thickness of 30–150 nm was observed for the aged sample. Some rod-shaped nanoscale β’ phases occurred in the aged Al matrix. After the solution and aging treatment, the steel layer recovered, and the γ-fibre texture increased. The tensile strength for individual Al alloy layer improved. The yield ratio of the aged clad sheet was lower than that of the initial sample. The tensile strength values of the composites were consistent with the computed values from the rule of mixture. The interfacial bonding strength of the initial sample was 70 MPa; the aged sample greatly improved and reached 130 MPa in strength.

Establishing copper‐zinc alloying strategy via active screen plasma toward stabilized zinc metal anode

AbstractThe problematic Zn dendrite for Zn anodes remains a great challenge. Constructing an artificial Cu‐Zn alloy layer is one of the most potential solutions. However, it is still challenging to prepare an ideal Cu‐Zn alloy layer with good morphology and controllable thickness. Herein, a special plasma‐based method of active screen plasma (ASP) is first reported to create a hexagonal close‐packed CuZn5 alloy layer with controllable morphology and thickness. Meanwhile, a “vaporization‐redeposition” mode is proposed to illustrate the alloying process. Based upon system analysis, the CuZn5 layer with good uniformity and appropriate thickness can regulate the behavior of Zn‐ion at electrode/electrolyte interface. The former homogenizes the electric field distribution, while the latter enhances de‐solvation ability of Zn‐ion, facilitating Zn‐ion diffusion. Consequently, the CuZn5‐coated Zn anodes display lower polarization potential and longer cycling life. Such CuZn5‐coated Zn anodes enable an outstanding cycle stability for Zn‐based devices, and the pouch devices also deliver practicality.image

Carburization of High-Temperature Alloys during Steam Cracking: The Impact of Alloy Composition and Temperature

Prior studies found that the carburization tendency is negligible for technically developed materials at temperatures below 900 °C, especially for Al-containing alloys compared to non-Al-containing alloys applied in steam cracking reactors. However, it is unclear whether this benefit remains at higher temperatures. This work compared coke deposition tendencies of recently developed alloys to each other and to a conventional material when cracking ethane at a higher temperature (950 °C) than previously reported. Under the studied experimental conditions, coking rates vary in the range of 1.22 × 10–6 to 20.5 × 10–6 kg/(m2·s) for Al-containing alloys, while for non-Al-containing alloys, coke deposition rates fall in a range of 4.95 × 10–6 to 33 × 10–6 kg/(m2·s). In general, aluminum-containing alloys showed less coke formation and improved stability against aging after five cracking cycles compared to the non-aluminum-containing materials. The results also showed that substantially less, if any, carburization could be detected in developed alloys even at high temperatures, in contrast to the results from a reference conventional alloy of 27/34 Cr–Ni. At higher temperatures, the protective oxide surface layer of the Al-containing alloys remained noticeably durable and integrated with negligible spallation compared to the ones of non-Al-containing alloys. In fact, the 27/34 Cr–Ni alloy showed the highest coking rate and carburization, implying the most vulnerable oxide surface layer relative to the other alloys. However, energy-dispersive X-ray (EDX) results showed no signs of carburization or deterioration of the surface of 27/34 Cr–Ni after experiments at 880 °C, indicating that both the temperature and matrix composition can play significant roles in determining the suitability of an alloy for application in steam crackers.

Strikingly reduced critical field in Ti-doped Kagomé YMn6Sn5.6Ti0.4 single crystal with large topological Hall effect

The Kagomé layered YMn6Sn6 alloy reveals large anomalous and topological Hall effects, implying tremendous application potential in spintronics devices. However, high critical magnetic field (the applied field corresponding to topological hall resistivity maximum) is likely to be a stumbling block to its practical application. In this work, a series of YMn6Sn6-xTix (x = 0, 0.4, 0.8, 1, 1.2) single crystals were prepared, in which the substitution of Ti for Sn sites is adopted to modify the exchange interaction between Mn layers in YMn6Sn6 alloy. The magnetic configurations and topological Hall effect are controlled resultantly. For YMn6Sn5.6Ti0.4 alloy, especially, the critical field reduces strikingly to less than 1T from near 4T or even higher [Sci. Adv. 6 (2020) eabe2680, https://doi.org/10.1126/sciadv.abe2680 and Phys. Rev. B 103 (2021) 014416, https://link.aps.org/doi/10.1103/PhysRevB. 103.014416]. What is more important, the topological Hall resistivity still remains relatively large value, ∼0.706 μΩ∙cm. In addition, large anomalous Hall conductivity of 55.7 Ω−1cm−1 is obtained in YMn6Sn5.6Ti0.4.

A Finite Volume Framework for the Simulation of Additive Friction Stir Deposition

Abstract In this study, a finite volume simulation framework was developed, validated, and employed for the first time in a new solid-state additive manufacturing and repair process, Additive Friction Stir Deposition (AFSD). The open-source computational fluid dynamics (CFD) code openfoam was used to simulate the deposition of a single layer of Aluminum Alloy 6061 feedstock onto a substrate, using a viscoplastic model to predict the flow behavior of the material. Conjugate heat transfer was considered between the build layer, the surrounding atmosphere, and the substrate, and the resulting temperatures were validated against experimental data recorded for three processing cases. Excellent agreement between simulated and measured temperature data was obtained, as well as a good qualitative prediction of overall build layer morphology. Further analysis of the temperature field was conducted to reveal the variation of temperature in the build direction, an analysis not possible with previous experimental or numerical methods, as well as a global heat transfer analysis to determine the relative importance of various modes of heat input and cooling. Tool heating was found to be the primary heat input to the system, representing 73% of energy input, while conduction to the substrate was the main mode of part cooling, representing 73% of heat loss from the build layer.

Characterization of complex surface oxide layers formed during the solidification of distinct Mg-RE alloys

Surface oxide layers play a significant role in forming secondary oxidation inclusions during the casting process. In this study, three typical Mg-RE alloys (Mg-3Nd (NZ30K), Mg-3Nd-3Gd (EV33) and Mg-3Nd-4Y (WE43A)) are selected. Their surface oxide layers formed during the solidification are characterized in detail, and the corresponding oxidation mechanisms are discussed. The results reveal that RE elements obviously influence the characteristics of surface oxide layers, which depends on their ability to purify the formed MgO in the melt via the reaction (2RE + 3MgO = 3Mg + RE2O3). On the one hand, as Nd and Gd do not easily displace MgO already formed in the melt, the loose oxide layers in NZ30K and EV33 alloys are mainly composed of MgO matrix with embedded RE-rich oxide particles. On the other hand, due to the strong ability of Y to purify MgO in the melt, the oxide layer of WE43A alloy becomes a denser and thinner Y2O3 oxide layer. Note that the differences in surface oxide layers well explain the different secondary inclusions that occur in three typical Mg-RE alloys during the casting process.

A simulation study on the influence of aircraft panel thickness on the cabin sound quality

Currently, noise control aims to optimise the psychoacoustic characteristics of aircraft interior noise to improve comfort and security during a flight. This study investigates the influence of transmission loss of aircraft panels on the sound quality of the cabin. We established an aircraft cabin acoustic model based on the statistical energy analysis method. The psychoacoustic parameters (i.e., loudness, sharpness, roughness, psychoacoustic annoyance, and articulation index) were simulated with the varying thickness of the aluminium alloy layer. Results showed that loudness and roughness significantly reduced, whereas sharpness increased with increasing thickness. The noise annoyance also declined as the thickness increased. However, the articulation index appeared a sudden drop when the thickness increased.