Alloy Foils Research Articles

Nb-doped VO2 single crystal microtube arrays

Nb-doped VO2 microtube arrays were fabricated by a thermal oxidation process of V–Nb alloy foils in air. The Nb-doped VO2 microtubes are featured with the rod-like, hollow, and rectangular cross-sectional single crystal, where arrays aligned nearly vertically on the surface of a Nb-doped V2O5 substrate. Phase transition examinations demonstrate that Nb doping can decrease the metal-insulator transition temperatures of VO2 by approximately 15 °C/at. % Nb, which reaches the highest decrease efficiency for metal-insulator transition temperatures of Nb-doped VO2. The phase transition route and mechanism of Nb-doped VO2 microtube arrays are revealed.

Development of a magnetic shield for 20-inch microchannel plate photomultiplier tubes

A newly developed 20-inch photomultiplier tube with good timing response and improved energy resolution uses a microchannel plate instead of traditional dynodes. Thin flexible sheets of high-permeability iron-based amorphous alloy foils encased in thin polyethylene terephthalate layers are used to shield the photomultiplier tube from the geomagnetic field. The work reported in this paper shows that the detection efficiency is increased by 87% on average with the help of this magnetic shield, and the number of secondary electrons is reduced by a factor of 2 for 20-inch MCP-PMT at LHAASO-WCDA.

Microstructural Changes and Hydrogen Permeability of Rolled and Annealed Nb<sub>30</sub>Ti<sub>35</sub>Co<sub>35</sub> Alloys

The relationship between the microstructural changes and hydrogen permeability of rolled and annealed Nb30Ti35Co35 alloys was investigated. The as-cast alloy had a lamellar structure that consisted of bcc-(Nb, Ti) and B2-TiCo phases. Hydrogen permeability decreased with increasing rolling reduction. The granule (Nb, Ti) phase formed in the TiCo matrix after annealing at temperatures of 1173 to 1373 K. The hydrogen permeability of the non-rolled alloys after annealing, which caused microstructural changes, was almost independent of annealing temperature. In contrast, the hydrogen permeability of the rolled alloys increased with increasing annealing temperature. It recovered to 90% of that for the as-cast alloy after annealing at 1373 K, which is higher than the value predicted by the mixing rule for the two phases. Therefore, rolling and annealing effectively increase the hydrogen flux for the industrial preparation of Nb–TiCo alloy foil for hydrogen production.

Defect character distribution regulation of alloy foil anode for high volumetric energy density lithium ion battery

Alloy foil anode exhibits an intriguing potential for high volumetric energy density (HVED) lithium ion batteries (LIBs). However, limited lithiation site and disproportionate lithiation rate of foil always induce sluggish lithiation kinetics, serious volume variation and stress concentration. Here, multiple length scaled defects of a Sn-Zn eutectic alloy foil including phase boundaries (PBs), grain boundaries (GBs), and dislocations (DLs) are synergistically densified as primary diffusion conduits to promote lithiation kinetics and uniform volume variation. Lithiation generated DLs can traverse cross the dense and strengthened PBs with semi-coherent lattice matching, delocalizing stress concentration and retarding crack initiation and propagation. Refined GBs also adsorb DLs for further stress relaxation. Over intrinsic DLs density aggravates stress concentration rather than relaxing due to immobile DLs accumulation. This defect character distribution dependent behavior endows LIBs with HVED (∼1000 Wh L−1) and good cycle performances, offering unprecedented options for intrinsically safe, low cost, and HVED LIBs.

Sacrificial Silver Recovery during Nanoporous Gold Formation by Electrolytic Dealloying of Gold-Silver Alloy

Electrolytic dealloying has proven to be a practical technique for fabricating nanoporous metals such as nanoporous Au (NP-Au). This widely studied material has novel properties that are useful in applications ranging from chemical sensing to energy storage. Building off the success of this field, issues concerning the sustainability of fabricating NP-Au through dealloying need to be further explored, such as the large amount of valuable sacrificial Ag material dissolved in solution after dealloying is complete. In this work, an electrolytic cell is created consisting of a Au–Ag alloy foil working electrode and a Ag foil counter and reference electrode immersed in a non-aqueous Ag+ ion electrolyte. When a small overpotential is applied, the working electrode is dealloyed to form NP-Au. Unique to this configuration, Ag removed from the working electrode is simultaneously plated on the counter electrode, resulting in high yield recovery of Ag sacrificial material, which can be used to create new Au–Ag parent alloys. This integrated process of simultaneous dealloying and recovery of the sacrificial material significantly improves the sustainability and economic viability of dealloying. From these results, a generalized electrolytic dealloying fabrication procedure is derived that can be extended to a wide range of nanoporous metals.

Исследование структуры и свойств быстрозатвердевших оловянно-цинковых эвтектических сплавов, легированных сурьмой

The study results of the phase composition, microstructure, and mechanical properties of rapidly solidified foils of Sn—Zn eutectic alloys doped with antimony are presented. Alloy foils are characterized by uniform distribution of components. The rapidly solidified eutectic alloy consists of dispersed separations of the zinc phase, distributed in a tin matrix; antimony forms an intermetallic compound with zinc. The rapidly solidified eutectic alloy doped with antimony has a microcrystalline structure, no texture is observed. At small grain sizes, twins are formed in eutectic alloys with antimony. The microhardness of the foils increases with increasing antimony concentration. At room temperature, during storage of rapidly solidified foils, decomposition of the supersaturated solid solution is observed. Annealing the foils leads to a decrease in microhardness and coarsening of the microstructure.

Microstructure and properties of pressure-less joining of SiCf/SiC composites by Ti–Si alloys

Prepared with pure Ti and Si powders as raw materials, the Ti16Si84 alloy (at. %) was obtained through refining in an intermediate frequency magnetic induction furnace. In this study, a novel method to join SiC fiber-reinforced SiC matrix composites (SiCf/SiC composites) under non-pressurized conditions is proposed using Ti16Si84 alloy foil as the joining material. The joining process was optimized, and the wettability, microscopic morphology, and bonding reaction of the joint were studied, along with the fracture characteristics and the bonding mechanism. Additionally, the corrosion resistance of the joints was examined in pure static water with high-dissolved oxygen (246 ppm) at 360 °C and 18.6 MPa. The results showed that Ti16Si84 alloy has good wettability with SiCf/SiC, enabling it to join SiCf/SiC successfully. The joint was composed of SiC, TiSi2, and Si, and there was no intermediate between them. When the brazing temperature was 1410 °C, the shear strength of the joint reached 42.5 MPa, and the joint integrity was favorable. After the shear test, numerous SiCf/SiC composites were torn by the solder, indicating their advantageous shear properties and high joint strength. After three days of corrosion, the joint samples' weight showed almost no changes. The corrosion depth was less than 20 μm and the residual shear strength of the corroded joined samples was 38.37 MPa, indicating excellent hydrothermal corrosion resistance of the joint material.

Thickness dependence of high volumetric energy density lithium ion battery based on Sn–Zn eutectic alloy foil anode

Thickness dependence of high volumetric energy density lithium ion battery based on Sn–Zn eutectic alloy foil anode

Hierarchical Co(OH)2 Dendrite Enriched with Oxygen Vacancies for Promoted Electrocatalytic Oxygen Evolution Reaction.

It is critical to develop efficient oxygen evolution reaction (OER) catalysts with high catalytic properties for overall water splitting. Electrocatalysts with enriched vacancies are crucial for enhancing the catalytic activity of OER through defect engineering. We demonstrated the dealloying method in a reducing alkaline solution using the Co5Al95 alloy foil as a precursor to produce a new oxygen-vacancy-rich cobalt hydroxide (OV−Co(OH)2) hierarchical dendrite. The as-synthesised OV−Co(OH)2 showed superior electrocatalytic activities toward OER when compared to pristine cobalt hydroxide (p–Co(OH)2), which had a low onset overpotential of only 242 mV and a small Tafel slope of 64.9 mV dec−1. Additionally, for the high surface area provided by the hierarchical dendrite, both p–Co(OH)2 and OV−Co(OH)2 showed a superior activity as compared to commercial catalysts. Furthermore, they retained good catalytic properties without remarkably decaying at an overpotential of 350 mV for 12 h. The as-made OV−Co(OH)2 has prospective applications as an anode electrocatalyst in electrochemical water-splitting technologies with the advantages of superior OER performances, large surface area and ease of preparation.

Neutron radial collimator using Zr–Gd alloy foil as collimating blade for engineering material diffractometer

In this study, 50-μm-thick Zr–Gd alloy foil was used as the collimating blade for a neutron radial collimator. Very thin Zr–Gd alloy foil presents excellent mechanical properties and low neutron transmission compared with a Mylar foil blade coated with gadolinium oxide (Gd2O3). The tensile strength of the 50-μm Zr–80Gd alloy foil is 135 MPa with a 4% thick tolerance, whereas the tensile strength for the 100-μm Mylar foil blade is 50 MPa with a 10% thick tolerance. The neutron transmission for 50-μm-thick Zr–80Gd alloy foil is 35.352% (1-Å neutron), which performs better than the Mylar foil blade because of the high content of gadolinium. Considering the blade thickness, the gauge volume width for different blade thicknesses was calculated analytically and optimized using McStas. The neutronic properties of a 2-mm gauge volume radial collimator with 240 blades of 50-μm Zr–80Gd alloy foils were simulated using MCNPX. The neutron-to-gamma ratio at the detector surface of the Zr–Gd alloy was higher than that of the Mylar foil blade. The transmission of the radial collimator was 93.6%, and a 2-mm gauge volume was simulated. The construction of a radial collimator using the Zr–Gd alloy blades is in progress. This shows that the Zr–Gd alloy foil provides a new type of high-quality neutron radial collimator blade.

Investigation on Thermomechanical Field Distribution by Various Electrothermal Modes for Wide Magnesium Alloy Foil

Investigation on Thermomechanical Field Distribution by Various Electrothermal Modes for Wide Magnesium Alloy Foil

Efficient drilling of amorphous alloy foils using low-energy long pulses of a Nd:YAG laser

Laser drilling of amorphous alloy foils was conducted using low-energy long pulses (LP) generated using a Nd:YAG laser. Results showed that LP can drill an amorphous alloy foil more efficiently than a nanosecond pulse (NSP) can: An LP at 1 mJ can open a through-hole on an amorphous alloy foil with 25 µm thickness although a single-shot NSP at 20 mJ formed a crater with ca. 3 µm depth. From these findings, we infer that the markedly higher drilling efficiency of a low-energy LP than that of NSP is attributable to 1) lower plasma generation by LP than by NSP, and 2) continuous heating of the target material by multiple sub-pulses in an LP. Results also demonstrate that low-energy LP drilling is applicable to various metal foils and that the drilling efficiency depends on the metal species. The results of the analysis of the relation between some physical properties of the metals and the drilling efficiency suggested that the drilling would proceed via melting of materials.

Novel Fabrication Routes of Metallic Micromembranes for In Situ Mechanical Testing

A methodology to miniaturize mechanical tests of metal alloys based on membrane deformation was developed in this investigation. The buildup of this new path for miniaturization tests requires small amounts of material for testing. This is of particular interest for irradiated structural nuclear materials. Micrometric metallic circular membranes were fabricated starting from thin alloy foils and using two different paths. Serial fabrication of microspecimens was performed by means of successive focused ion beam (FIB) steps. On the other hand, high-throughput parallel fabrication was achieved by differential sputtering (DS) based on reactive ion etching followed by a final fine FIB polishing to flatten the membranes and straighten the mechanical response. Micro-punch tests were performed using spherical tips and the in situ load–displacement curves were recorded while monitoring the test in a scanning electron microscope. The values reached after testing of the DS membranes were more reliable than those of FIB samples, showing a large stretching section and higher values of maximum force (64 mN) and displacement (22.2 μm). The micro-punch testing methodology developed in this work combines the advantage of facilitating the interpretation of the mechanical response, by producing a bi-axial stress distribution during membrane stretching, while being amenable to high-throughput microspecimen fabrication.

Cryogenic Mechanical Prelithiation Reduces Porosity and Improves Battery Performance of an Alloy Foil Anode.

Anode prelithiation could dramatically improve the initial Coulombic efficiency and battery life. Roll-to-roll mechanical prelithiation (MP) is an attractive option for achieving prelithiation in minutes. While our previous work on metallic-foil prelithiation revealed that an external pressure is necessary to achieve MP in a timely fashion, too high an applied pressure will cause severe damages in the form of porosity and cracking. Thus, gentler MP under smaller pressure, and surprisingly, cryogenic temperatures, while prepositioning prolific grain boundaries as lithium diffusion paths is critical. To this end, first, we developed an accumulative roll bonding (ARB) method to refine the grain size of Sn-5Sb foil for denser grain boundaries. After ARB of 12 cycles (ARB-12), the grain size of Sn-5Sb foil decreased from 20-50 to 0.5-1.5 μm. Then, MP was performed under a mild condition of 0.5 MPa and -20 °C. Thereby, the porosity of prelithiated ARB-12 was reduced to 1.8% from thickness measurement, significantly minimizing the prelithiation damage. As a result, due to grain refinement, we achieved lower interface impedance and better rate performance. The ARB-12 Sn-5Sb foil with a proper prelithiation design exhibited 180 and 110 stable cycles when pairing with commercial LFP and NCM811 cathodes. Furthermore, it also depletes less electrolyte and keeps higher capacity retention under -10 °C than that of the graphite anode.

Periodic ultrasound-assisted electrodeposition of Fe–Ni alloy foil

Periodic ultrasound was introduced into the electroforming process to electrodeposit Fe–Ni foil layers with high properties and low coefficient of thermal expansion that satisfied the requirements for avionics packaging. Electrochemical analysis and morphological testing indicated that periodic ultrasound can sufficiently weaken the stripping effect caused by continuous high-power ultrasonic treatment. Under periodic ultrasonic treatment, applying both high current density and high ultrasonic power in the electroforming system is possible. By adjusting the current density and the duty cycle, Fe–Ni deposits with coefficients of thermal expansion (CTEs) ranging from 2.96 to 6.71 × 10−6/ °C were obtained. Compared to Fe–Ni alloys prepared via traditional electrodeposition methods, the Fe–Ni layers obtained in this study exhibit a larger range of CTE values and great improvements in other physical and mechanical properties. The Fe–Ni alloy foil obtained at a duty cycle of 0.57 and current density of 1 A/dm2 possessed a low surface roughness of 0.95 μm, the iron content of 63 wt.%, micro-hardness of 373.1 HV, Young's modulus of 133.7 MPa, and CTE of 5.39 × 10−6/ °C.

Influence of Interfacial Stress Produced by MAO on Electrochemical Corrosion and Stress Corrosion Cracking Behavior in 7075 Aluminum Alloy

The interfacial stresses of micro arc oxidation (MAO) coated 7075 Al alloy foil samples were measured by a deflection method. The results showed that compressive stresses were generated on the substrate-coating interface of the samples coated for different oxidation times. Electrochemical tests and slow strain rate tensile tests in a 3.5 wt% sodium chloride solution indicated that the compressive stress played a positive role in corrosion and stress corrosion cracking (SCC) resistance. The findings of this work indicated that the MAO coating can not only act as a protective layer to hinder corrosive solution, but also the compressive stress generated during MAO process can offset part of the external stress and reduce the hydrogen penetration during SCC.

A freestanding nanoporous NiCoFeMoMn high-entropy alloy as an efficient electrocatalyst for rapid water splitting

The development of low-cost non-noble-metal-based electrocatalysts that can work stably at high current densities is crucial to apply a hydrogen evolution reaction (HER) and an oxygen evolution reaction (OER) in electrolyzed water. This study developed a freestanding nanoporous high-entropy alloy foil as a dual-functional electrocatalyst. The proposed electrocatalyst combines dealloying and polarization and shows excellent electrocatalytic activity in an alkaline electrolyte. It has an extremely small overpotential of 150 mV at 1,000 mA cm−2 for the HER and a low Tafel slope of 29 mV dec−1. At the same current density, the overpotential of the OER is only 350 mV. The alkaline electrolyzer using the electrocatalyst as both anode and cathode requires a cell voltage of only 1.47 V to output a stable current density of 10 mA cm−2. This enables it to be an efficient bifunctional electrocatalyst for alkaline overall water splitting and better stability for more than 375 h of continuous hydrogen production while providing substantial material cost savings relative to platinum. Density functional theory calculations indicate that the ultrahigh HER activity of the catalyst originates from the synergetic effect of optimized hydrogen adsorption in the segregation area and enhanced H2O adsorption in the un-segregation area produced by spinodal decomposition.

Synergistic Manipulation of Na+ Flux and Surface-Preferred Effect Enabling High-Areal-Capacity and Dendrite-Free Sodium Metal Battery.

The propensity of sodium anode to form uniform electrodeposit is bound up with the nature of electrode surface and regulation of Na‐ion flux, as well as distribution of electronic field, which is quite crucial for high‐areal‐capacity sodium metal batteries (SMBs). Herein, a novel metallic sodium/sodium–tin alloy foil anode (Na/NaSn) with 3D interpenetrated network and porous structure is prepared through facile alloy reaction. The strong sodiophilic properties of sodium–tin alloy can lower the nucleation energy, resulting in smaller depositing potential and strong adsorption of Na+, while synergistic effect of porous skeleton and additional potential difference (≈0.1 V) between Na and Na–Sn alloy (Na15Sn4) can alleviate volume expansion, redistribute the Na‐ion flux and regulate electronic field, which favors and improves homogeneous Na deposition. The as‐fabricated Na/NaSn electrode can endow excellent plating/stripping reversibility at high areal capacity (over 1600 h for 4 mAh cm−2 at 1 mA cm−2 and 2 mAh cm−2 at 2 mA cm−2), fast electrochemical kinetics (500 h under 4 mAh cm−2 at 4 mA cm−2) and superior rate performances. A novel strategy in the design of high‐performance Na anodes for large‐scale energy storage is provided.

Структура и свойства быстрозатвердевших фольг тройного сплава Bi – In – Sn и спаянного соединения на его основе

The alloy Bi32In41Sn27 was produced by fusing the components in quarts ampoules. A piece of alloy of 0.2 g was heated and injected onto the inner polished surface of rapidly rotating copper cylinder with a diameter 20 cm. The alloy was solidified in the form of a foil up10 cm long and up to10 mm wide. Foils with a thickness of 30 – 100 micrometers were used for the study. The chemical compositions of the foil in the layers in contact with surface of the mold and the atmosphere are coincided within the measurement error. A rapidly solidified alloy Bi32In41Sn27 consists of ε-phase (BiIn) and γ-phase (Sn4In) having a dispersed structure. The average value of the chords dγ of random secants located on the sections of γ-phase and average value of the specific surface area of the interphase boundary Sε – γ, formed by ε- and γ-phases, depend on the expose time t at room temperature; their properties are described by equations d = 0,58 + 0,29lnt and Sε – γ = 2,9 − 0,43lnt, correspondly. The alloy foils have a microcrystalline structure and well-defined texture (0001) of the γ-phase and poorly expressed double (211) + (112) of the ε-phase. Texture are persist during annealing 60 °С for 2 hours. The microhardness of the alloy Bi32In41Sn27 foils monotonically increases with increasing expose time at room temperature and reaches saturation. Subsequent isothermal annealing at 60 °С leads to a microhardness value equal to it of massive sample. The distribution of components in the solder joint between copper plates was investigated. Indium and tin diffuse into the copper plates. The depth of penetration of copper into the joint reaches 3 micrometers. When the soldered copper plates are strained, the breakdown on the junction occurs at 790 N and absolute value of the deformation is 0.8 mm. The conducted investigations of copper solder joints indicate the possible practical use of the alloy Bi32In41Sn27 foil as a solder.

Vancomycin is effective in preventing Cutibacterium acnes growth in a mimetic shoulder arthroplasty

Intra-incisional deposition of vancomycin powder is a strategy to limit Cutibacterium acnes infection after shoulder surgery. Unfortunately, limited research exists examining the effectiveness of vancomycin in a clinically relevant joint infection model. This basic science study investigated the efficacy of vancomycin administration as prophylaxis for C acnes growth invitro using a mimetic shoulder arthroplasty. A new bioartificial shoulder joint mimetic implant (S-JIM) was used to investigate the effect of vancomycin powder on Cacnes growth within the first 48 hours after surgery. The impact of vancomycin was assessed on a skin-derived (ATCC 11827) Cacnes strain and a periprosthetic joint infection-derived strain. C acnes strains were applied to titanium alloy foil and embedded beneath multiple layers of collagen-impregnated cellulose scaffold strips containing human shoulder joint capsular fibroblasts, facilitating the development of an oxygen gradient with an anaerobic environment around the foil and inner layers. Ten milligrams of vancomycin powder was applied between the C acnes layer and the human cell-containing scaffold strips to model direct antibiotic application, and intravenous vancomycin prophylaxis was modeled by adding vancomycin in media at 5 or 20 μg/mL. After 48 hours, the Cacnes inoculum layer was subcultured from each S-JIM onto agar plates to assess the formation of viable C acnes colonies. Primary human shoulder capsule cells were assessed microscopically to detect any detrimental effects of vancomycin on cellular integrity. Agar plates inoculated with extracts from untreated S-JIMs consistently resulted in the growth of large numbers of C acnes colonies, whereas treatments with vancomycin powder or vancomycin in media at 20-μg/mL dilution effectively prevented the recovery of any C acnes colonies. The lowest vancomycin dilution tested (5 μg/mL) was insufficient to prevent the recovery of C acnes colonies. Vancomycin powder had no discernible short-term impact on shoulder capsule cell morphology, and the presence of these cells had no discernible impact on vancomycin degradation over time. Vancomycin administration effectively prevented C acnes growth in a bioartificial S-JIM. These results support the hypothesis that intra-incisional vancomycin application may limit C acnes prosthetic joint infections.