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A numerical study on the two-layer liquid sloshing with a free surface in a rectangular tank under horizontal sinusoidal excitation is investigated in this work. It is observed that the interface displacement is mainly influenced by the lower liquid depth, while the free surface displacement primarily depends on the total liquid depth. Using dimensional analysis of the numerical results, we obtained a fitting curve in the S-model expression, which relates the displacements of both liquids to the forcing amplitude, forcing frequency and liquid depth. Furthermore, distinct from the phenomena for a single-layer liquid, we find that the sum and difference frequencies play significant roles in the power spectral density curves. There are similar power spectral density curve shapes and energy concentration locations with a fixed type of excitation independent of the liquid filling depth and layer depths ratio. • The influence of liquid depths on interfaces' oscillation is studied. • Fitting curves are provided through dimensional analysis. • The significance of sum/difference frequencies in PSD curves is investigated. [ABSTRACT FROM AUTHOR]

Fluid flow through fractures is central to many engineering applications and geophysical processes. Although the intertwined effects of aperture heterogeneity and inertial forces on fluid flow have been interrogated in last few decades, it remains challenging to accurately predict fracture flow field at high pressure gradient conditions when inertial effects are significant. To address this challenge, we rigorously derived a depth-averaged nonlinear flow model by introducing a quadratic velocity term into the linear flow model (i.e., Local Cubic Law that describes a linear relationship between pressure gradient and fluid flux) at the mechanistic level. The supporting laboratory experiments and direct numerical simulations through six rough-walled fractures with varying roughness further confirmed the robustness of the proposed model. We found that the predictive model outperforms existing alternatives with acceptable relative errors in mean velocity (<7%) considering a broad range of Reynolds number (0.01–167), suggesting its superior performance of handling pronounced inertial effects. Lastly, we parameterized the new model by establishing an empirical function that related parameter (ω) in the model to measurable fracture properties (i.e., aperture); this makes the predictive model viable and straightforward for predicting local velocity fields in pressurized engineered environments. • We derived a nonlinear fracture flow model accounting for significant inertial effects. • The proposed model is validated via laboratory and numerical flow tests at high pressure conditions. • The proposed model can be possibly parameterized based on measurable fracture properties. [ABSTRACT FROM AUTHOR]

The influences of low growth temperatures (420–490 °C) on phase transition of Ga 2 O 3 films grown on Al 2 O 3 substrates by means of metal-organic chemical vapor deposition (MOCVD) are investigated here. The changes of crystal structure, phase composition, surface and cross-sectional morphologies are carried out by X-ray diffraction, atomic force microscope and field-emission scanning electron microscope to reveal the detail evolution from ε -phase to β -phase in Ga 2 O 3 films. The fluctuant Gibbs free energy change relying on growth temperature induces different growth mechanism of Ga 2 O 3 films. Furthermore, the ultraviolet photoresponse properties of different phase compositions for Ga 2 O 3 films are compared by constructing metal-semiconductor-metal photodetectors. It is found that mixture phase Ga 2 O 3 films express better photodetection performance than pure phase Ga 2 O 3 films due to the formation of built-in field within phase junction. This proposed regulation principle of Ga 2 O 3 phase transition provides a new route to high-performance photoelectric material. • Phase transition from ε -Ga 2 O 3 to β -Ga 2 O 3 was captured in a low growth temperature window of 420–490 °C by MOCVD. • Different Ga 2 O 3 phase compositions resulted in varying crystal structures, surface morphologies and UV sensing properties. • Ga 2 O 3 films with mixture phases demonstrated better photoresponse due to the formation of built-in field within phase junction. [ABSTRACT FROM AUTHOR]

• A β-Ga 2 O 3 /CuBiI 4 heterojunction deep-ultraviolet photodetector was constructed. • The fabricated device exhibited responsivity of 20.68 A/W and detectivity of 3.72 × 1015 Jones. • The detector could display self-powered operation. Herein, a β-Ga 2 O 3 /CuBiI 4 heterojunction deep-ultraviolet (DUV) photodetector was constructed based on metal-organic chemical vapor deposition grown β-Ga 2 O 3 film and spin-coated CuBiI 4 film. In which, we prepared the pure and well-crystallized CuBiI 4 film from environment-friendly materials under optimized experimental conditions. The fabricated device exhibited a large responsivity of 20.68 A/W, a high specific detectivity of 3.72 × 1015 Jones, a high photo-to-dark current ratio of 5.62 × 106, a low dark current of 0.385 pA, and an ultrahigh UV/visible rejection ratio (R 250 nm / R 400 nm) of 1.14 × 104 under 254 nm UV light illumination at 5 V. In all, the device can sensitively monitor a wide range of UV light (254 nm) intensities from 0.1 to 2000 μW/cm2. Moreover, the potential of the device operating under self-powered mode has been verified, and the intrinsic physical mechanism of the heterojunction photodetector was analyzed via energy-band alignment. Overall, this work would present a promising route to realize high-performance and cost-effective DUV photodetector. [ABSTRACT FROM AUTHOR]

• We develop a theoretical framework for estimating the effective pore volume of preferential fracture-porous media flow systems. • The proposed framework is validated by using two distinctive numerical examples with preferential flow paths at multiple length scales. • The theoretical framework is a promising approach with high accuracy that can account for subsurface heterogeneity found at multiple scales. Pores in the subsurface form during the Earth forming process, e.g., sedimentation and diagenesis which evolve over the geologic time scale. Pores serve as the needed 'room' for the storage of natural resources and for transporting various fluids. Therefore, quantifying the volume of pores, i.e., the pore volume, is central to many geophysical and engineering problems. However, an accurate determination of subsurface pore volume has remained a challenge, primarily related to the spatial heterogeneity found at multiple length scales. Here, we develop a theoretical framework to quantify the effective pore volume of a multiscale heterogeneous porous matrix and preferential fracture flow system by evaluating groundwater age or residence time of an inert tracer. The robustness of the proposed theoretical model is tested against numerical solutions from a typical fracture (network)-matrix flow system with heterogeneous pore space distribution. We find that, although there are some uncertainties for the application of theory by measuring groundwater age or solute breakthrough curves, our proposed theoretical model is overall robust and insensitive to the length scales with relative errors of less than 9% in estimated effective pore volume. In contrast, traditional methods remain either unrepresentative or lack resolution for determining subsurface pore volume in heterogeneous formations. [ABSTRACT FROM AUTHOR]

• Solution processed VOx films obtain changeable conductivities in 2 orders of magnitude range. • Regulable conductivity of VO x enables effective hole-transport engineering in VO x /Ga 2 O 3 heterojunction. • Optimized VO x /Ga 2 O 3 photodetector demonstrates enhanced self-powered ultraviolet photodetection performance. The self-powered photodetection performance of the VO x /Ga 2 O 3 heterojunction photodetector could be effectively and positively regulated via the VO x hole transport layer by charge-carrier engineering, inducing the record PDCR of 1.08 × 108 and superhigh on/off ratio of 1.23 × 106. [Display omitted] As the carrier behavior is crucial to the photoelectric conversion process, the charge-carrier engineering could provide feasible strategy for high-performance photodetector (PD). Herein, self-powered ultraviolet PDs were constructed on VO x /Ga 2 O 3 (VGO) heterojunctions by adopting the solution processed VO x films as hole transport layer (HTL). Treated with different annealing ambients, the HTL demonstrated changeable conductivities due to the regulated crystallinities, phase structures and chemical valences, which further exerted influences on the VGO PDs inducing controllable photodetection properties. With effective hole transportation, low valence band barrier and large built-in field, the modulated VGO PDs achieved enhanced self-powered photodetection performance with photo-to-dark current ratio of 1.08 × 108, on/off ratio of 1.23 × 106, rejection ration (R 245 / R 400) of 3.12 × 104, responsivity of 28.9 mA/W and detectivity of 1.13 × 1014 Jones as well as rise/decay time of 57/74 ms. In consideration of the carrier-transport problems are commonly ubiquitous and particularly vital, our proposed HTL engineering method could open the high-performance route for self-powered ultraviolet PDs. [ABSTRACT FROM AUTHOR]

• Co 3 O 4 nanowire networks were synthesized by a solvothermal following heat treatment. • The amorphization and porous structure of Co 3 O 4 was induced by electrochemical lithiation. • The 5-cycle Co 3 O 4 catalyst exhibits prominent OER property in alkaline system. Description: A green and economical electrochemical method is used to obtain an amorphous 3D porous Co3O4 nanowire network with excellent OER performance. [Display omitted] Co 3 O 4 has been proven to be a potential catalyst for oxygen evolution reaction (OER) because of its low cost and abundant resources. However, pure Co 3 O 4 has the disadvantages of poor conductivity and low catalytic activity. Here, we successfully synthesized three-dimensional (3D) network Co 3 O 4 composed of nanowires grown on nickel foam (NF). Using a lithium-ion rocking chair transport mechanism, Co 3 O 4 nanowires were transformed into porous amorphous Co 3 O 4 , which greatly reduces the resistance in the OER process and enhances active site exposure. Meanwhile, the increase of Co2+ greatly improved the OER performance. However, excessive cycling of lithium-ion batteries can form a thick solid electrolyte interface (SEI) on the surface, which has a negative impact on OER. Specifically, we found that 5-cycle Co 3 O 4 has the best OER performance, showing an initial potential of 1.42 V vs RHE, a reduced overpotential of 311 mV at 50 mA cm−2 and a low Tafel slope of 76 mV decade−1, which is better than commercial RuO 2. [ABSTRACT FROM AUTHOR]

Herein, a CuSCN/Ga 2 O 3 heterojunction device was fabricated by spin-coating and metal-organic chemical vapor deposition (MOCVD) methods. Under the irradiation of 254 nm deep ultraviolet (DUV) light with an intensity of 1000 μ W/cm 2 , the device shown high sensitivity and favorable self-powered performances with photo-to-dark current ratio (PDCR) of 1.29 × 10 4 , photo responsivity (R) of 5.5 mA/W, rejection ratio (R 270nm / R 600nm) of 4.33 × 10 3 , and specific detectivity (D ∗) of 3.8 × 10 11 cm Hz 1/2 W − 1 (Jones) at − 5 V. In addition, the device has a rise time of 0.45 s and 3.80 s, and a decay time of 0.26 s and 0.26 s. In general, the CuSCN/Ga 2 O 3 heterojunction prepared in this work may well be a potential candidate for achieving a self-powered and high-performance DUV photodetector. • A p-CuSCN/n-Ga 2 O 3 thin film heterojunction is constructed for performing DUV detection. • Under the irradiation of 254 nm DUV light with an intensity of 1000 μ W/cm2, at bias of -5 V, the device shown good performances. • The heterojunction photodetector could operate at zero bias. [ABSTRACT FROM AUTHOR]

[Display omitted] • WEGN improved learning and memory, and reversed histological alterations in rat. • WEGN exhibited obvious antioxidant activity. • WEGN contributed to the stability of the central cholinergic system. • WEGN significantly increased Ach content and ChAT activity, but suppressed AChE activity, and contributed to the stability of the central cholinergic system. Wheat embryo globulin nutrient (WEGN), with wheat embryo globulin (WEG) as the main functional component, is a nutritional combination that specifically targets memory impairment. In this study, we explored the protective role of WEGN on Alzheimer's disease (AD)-triggered cognitive impairment, neuronal injury, oxidative stress, and acetylcholine system disorder. Specifically, we established an AD model via administration of d -galactose (d -gal) and Aluminum chloride (AlCl 3) for 70 days, then on the 36th day, administered animals in the donepezil and WEGN (300, 600, and 900 mg/kg) groups with drugs by gavage for 35 days. Learning and memory ability of the treated rats was tested using the Morris water maze (MWM) and novel object recognition (NOR) test, while pathological changes and neuronal death in their hippocampus CA1 were detected via HE staining and Nissl staining. Moreover, we determined antioxidant enzymes by measuring levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in serum, cortex, and hippocampus, whereas changes in the acetylcholine system were determined by evaluating choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) activities, as well as choline acetylcholine (Ach) content. Results revealed that rats in the WEGN group exhibited significantly lower escape latency, as well as a significantly higher number of targeted crossings and longer residence times in the target quadrant, relative to those in the model group. Notably, rats in the WEGN group spent more time exploring new objects and exhibited lower damage to their hippocampus neuron, had improved learning and memory activity, as well as reversed histological alterations, relative to those in the model group. Meanwhile, biochemical examinations revealed that rats in the WEGN group had significantly lower MDA levels and AChE activities, but significantly higher GSH, SOD, and ChAT activities, as well as Ach content, relative to those in the model group. Overall, these findings indicate that WEGN exerts protective effects on cognitive impairment, neuronal damage, oxidative stress, and choline function in AD rats treated by d -gal/AlCl 3. [ABSTRACT FROM AUTHOR]

Biomimetic superhydrophobic surfaces have attracted considerable attention and are gradually being used in real-life applications. To fabricate such surfaces, a fluorination-based strategy has shown excellent superhydrophobicity and liquid repellency. However, its usage is limited by weak mechanical stability and potential dangers to natural environments and humans. Here, the naturally occurring superhydrophobicity of purple orchid leaves is reported in detail. Inspired by the purple orchid leaves, this study presents an eco-friendly strategy to fabricate biomimetic superhydrophobic surfaces by electrodepositing nanoscale organometallic coatings on laser-patterned microstructures, which aim to enhance the mechanical stability and to approximate biological samples in terms of morphology and composition. Such a biomimetic surface has the same wettability as purple orchid leaves (with a water contact angle of 163.54 ± 1.59°). Experiments indicate that the biomimetic surface has a low roll-off angle (minimum to 4.23 ± 0.39°) and can repel a variety of liquids. The impacting droplets can bounce off the biomimetic surface 6 times within 300 ms, and the stationary droplets can be ejected between two squeezed biomimetic surfaces. These phenomena demonstrate that the biomimetic surface has low adhesion and excellent liquid repellency. Remarkably, the synergistic effect of the nanoscale organometallic coatings and the laser-patterned microstructures greatly enhances the mechanical stability of the biomimetic surfaces, which remains superhydrophobic even after 100 abrasion cycles. [Display omitted] • The naturally occurring superhydrophobicity of purple orchid leaves was reported in detail. • Electrodepositing organometallic nano-coatings on laser-patterned microstructures to obtain biomimetic superhydrophobicity. • The obtained superhydrophobic surface approximate biological samples in terms of morphology and composition. • The synergistic effect of organometallic coatings and laser-patterned microstructures improve the mechanical stability. [ABSTRACT FROM AUTHOR]

Normally, the synthesis of the BaTiO 3 nanowires is via the ion exchange of K 2 Ti 8 O 17 nanowires with Ba2+ under hydrothermal conditions. The concentration of the Ba2+ should be maintained at a low concentration to slow the ion exchange for preventing the crush of templates, thus reducing the quality and yield of the nanowires. In this paper, insoluble barium salt, that is, barium carbonate (BaCO 3) powder was used as a Ba2+ sustained release agent, which can release a sufficient amount of Ba2+ and keep the low concentration of Ba2+ for ion exchange. The BaTiO 3 nanowires with an ultra-high aspect ratio were prepared by this strategy. Thereafter, XRD, SEM, etc. Were used to characterize the as-obtained samples. Results showed that the obtained nanowires possess an average diameter of 11.6 nm and length up to several microns. Compared with other easily soluble barium salts, BaCO 3 can reduce the cation exchange rate and increase the nucleation and growth of BaTiO 3 nanowires. Additionally, reliable and reproducible experimental phenomenon showed that the above method has obvious advantages in large-scale production and high consistency, which provides an essential strategy for the application of BaTiO 3 nanowires in flexible electronic devices, especially in capacitive sensors, film-type capacitors, and energy-storage devices. • The synthesized BaTiO 3 nanowires are with an ultra-high aspect ratio (>500). • Insoluble barium salt was used as a Ba2+ sustained release agent. • This work provides an essential strategy for BaTiO 3 nanowires synthesis. [ABSTRACT FROM AUTHOR]

• We rationally design and construct a novel Co 0.6 Fe 0.4 S 2 @N-CNTs/rGO nanohybrid. • Co 0.6 Fe 0.4 S 2 @N-CNTs/rGO demostrates excellent electrocatalytic performance for OER. • Co 0.6 Fe 0.4 S 2 @N-CNTs/rGO outperforms commercial RuO 2 and most Co/Fe-based catalysts. • The superb catalytic performance owes to rational composition and structure design. [Display omitted] We rationally design and construct a heterostructured hybrid with reduced graphene oxide served as a platform to in-situ grow N-doped bamboo-like carbon nanotubes encapsulating bimetallic Co–Fe sulfide nanoparticles through a two-stage pyrolysis succeeded by an evaporating sulfurization process (denoted as Co x Fe 1- x S 2 @N-CNTs/rGO). By tuning the Co/Fe ratio, the optimal Co 0.6 Fe 0.4 S 2 @N-CNTs/rGO exhibits a remarkable oxygen evolution reaction (OER) performance in 1.0 M KOH, in which the overpotential at 10 mA cm−2 and Tafel slope are recorded as 248 mV (vs. RHE) and 58.3 mV dec−1, respectively, outmaneuvring commercial RuO 2 and most Co/Fe sulfide-based catalysts in recent peer reports. Comprehensive experiment results unravel that the outstanding OER electrocatalytic performance owes to the reinforced synergy between CoS 2 and FeS 2 , the heterostructures constituted by partial CoS 2 and FeS 2 , the confining effect of N-CNTs/rGO for CoS 2 and FeS 2 nanoparticles, and the high conductivity and large surface of N-CNTs/rGO. [ABSTRACT FROM AUTHOR]

Gas tungsten arc (GTA) cladding has the advantages of flexibility, low cost, and high quality. AlCoCrFe x Ni (x = 1.0, 1.4, 2.1, 3.0, denoted as S-150, S-160, S-170, S-180, respectively) HEA coatings are prepared by GTA cladding on a low carbon steel substrate using different specific heat input (cladding current). The microstructure and phase structure are investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), electron backscattered diffraction (EBSD). The mechanical properties are investigated by microhardness, nanoindentation. The corrosion properties are investigated by open circuit potential (OCP), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results show that the coating alloys mainly contain an A2 + B2 structure, and the grain boundaries of S-150 are Cr-rich σ phase. With the increase of specific heat input, the grain size becomes larger and the morphology changes from equiaxed to columnar. S-180 displays lower hardness and more active room-temperature creep deformation than S-150, which is attributed to the reduction in grain boundary strengthening, solid solution strengthening, and precipitate strengthening. S-180 displays better corrosion resistance than S-150. The typical corrosion type of S-150 and S-180 is pitting corrosion and intergranular corrosion, respectively This research contributes to the fabrication of large-thickness and large-area corrosion-resistant and wear-resistant HEA coatings. [Display omitted] • AlCoCrFe x Ni (x = 1.0, 1.4, 2.1, 3.0) HEA coatings are prepared by gas tungsten arc cladding. • AlCoCrFeNi HEA coatings have equiaxed and columnar grains with A2 + B2 + σ structure. • The mechanical properties deteriorate as cladding specific heat input increases. • The corrosion types of coatings are pitting corrosion and intergranular corrosion. [ABSTRACT FROM AUTHOR]

• We demonstrate a facile route to fabricate a novel CoO–CoSe 2 @N-CNTs/rGO nanohybrid. • CoO–CoSe 2 @N-CNTs/rGO shows excellent electrocatalytic performance for OER. • CoO–CoSe 2 @N-CNTs/rGO outperforms commercial RuO 2 and most Co-based electrocatalysts. • The superb catalytic performance owes to rational composition and structure design. Constructing CoO–CoSe 2 heterostructures through partial selenization of CoO is proposed to ameliorate the electrocatalytic performance of Co-based compounds toward oxygen evolution reaction (OER). Moreover, with reduced graphene oxide as a platform to in-situ grow N-doped bamboo-like carbon nanotubes encapsulating part of CoO and CoSe 2 nanoparticles, we fabricated a novel hybrid (denoted as CoO–CoSe 2 @N-CNTs/rGO) via a combination of two-stage calcination and subsequent selenization treatment. As an OER electrocatalyst in 1.0 M KOH, CoO–CoSe 2 @N-CNTs/rGO affords low overpotentials (250 mV@10 mA cm−2 and 322 mV@100 mA cm−2), favorable kinetics (a Tafel slope of 68 mV dec−1), and excellent durability, outperforming commercial RuO 2 and most Co-based electrocatalysts reported till date. Comprehensive experiment results uncover that the exceptional electrocatalytic performance mainly emanates from the synergistic effect between CoSe 2 and CoO in heterostructure, N doping effect in CNT and rGO, and the confining effect of N-CNTs and rGO for CoO–CoSe 2 , resulting in more active sites and enhance conductivity. More importantly, density functional theory calculations disclose that the concurrent N doping and desirable encapsulation of the CoO–CoSe 2 nanoparticle in N-CNT can optimize the adsorption energies of OER intermediates and increase the electric conductivity, thereby expediting the OER. This work is helpful to foster understanding on the structure–performance correlations of electrocatalysts with multi-active sites and multi-components for diverse applications. [ABSTRACT FROM AUTHOR]

With existing power prediction algorithms, it is difficult to satisfy the requirements for prediction accuracy and time when PV output power fluctuates sharply within seconds, so this paper proposes a high-precision and ultra-fast PV power prediction algorithm. Firstly, in order to shorten the optimization time and improve the optimization accuracy, the single-iteration Gray Wolf Optimization (SiGWO) method is used to simplify the iteration process of the hyperparameters of Least Squares Support Vector Machine (LSSVM), and then the hybrid local search algorithm composed of Iterative Local Search (ILS) and Self-adaptive Differential Evolution (SaDE) is used to improve the accuracy of hyperparameters, so as to achieve high-precision and ultra-fast PV power prediction. The power prediction model is established, and the proposed algorithm is applied in a test experiment which can complete the power prediction within 3 s, and the RMSE is only 0.44%. Finally, combined with the PV-storage advanced smoothing control strategy, it is verified that the performance of the proposed algorithm can satisfy the system's requirements for prediction accuracy and time under the condition of power mutation in a PV power generation system. [ABSTRACT FROM AUTHOR]

Earthquake gates are fault geometric complexities, common in natural fault systems, that conditionally impede earthquake ruptures. This study centers on modeling of multicycle dynamics of the Pingding Shan earthquake gate along the central Altyn Tagh Fault in northwest China. The earthquake gate includes three geometric complexities: a prominent restraining bend, a 4-km wide stepover to the east, and a releasing bend to the west. We use a 2D finite element method to simulate coseismic spontaneous ruptures with interseismic fault stress evolutions computed by an analytic viscoelastic solution. Paleoseismic records and long-term slip-rates are used to constrain the models. We find that fault-geometry-related heterogenous stresses accumulated over earthquake cycles yield complex rupture patterns and help explain earthquake recurrence intervals revealed by paleoseismic records. The three most important contributions to the heterogeneous stresses come from dynamic ruptures passing fault geometric complexities, fault-strike-dependent tectonic loading and relaxation, and stress history from past earthquakes. In the Pingding Shan earthquake gate, the releasing stepover appears to impede ruptures more effectively than the restraining bend. The combined impact of the restraining bend and the releasing stepover makes the Pingding Shan earthquake gate a very effective barrier to 350-km model-spanning ruptures. The best-fit model yields a low recurrence interval of 4.6 kyrs for 350-km-long ruptures, interspersed with more frequent ruptures limited to individual fault segments. A lower static friction tends to reduce the effectiveness of the earthquake gate to impede ruptures. Local fault geometric complexities together with rapid energy release and restrengthening of friction during dynamic ruptures help explain the 0.66 recurrence interval coefficient of variation (COV) recorded at the Copper Mine paleoseismic trench site on the Xorxoli segment. This study provides a method for applying heterogenous initial stresses for single-event dynamic rupture simulations that consider the effect of past earthquakes and fault geometry. • Multicycle dynamics of Pingdingshan earthquake gate on Altyn Tagh fault is modeled. • The model is observation-constrained and predicts an effective Pingdingshan gate. • Dynamic ruptures on realistic fault geometry over cycles yield stress heterogeneity. • The heterogeneity is geometry-related and explains 0.66 COV in paleoseismic record. • The study demonstrates the critical role of fault geometry in earthquake dynamics. [ABSTRACT FROM AUTHOR]

The excellent mechanical and corrosion properties make high-entropy alloys (HEA) be promising structural and coating materials. However, problems like element segregation hinder the fabrication and application of HEA. Ultrasonic melt treatment (USMT) generally has the effect of segregation suppression. In the present study, the impact of ultrasonic treatment on the microstructure, segregation, mechanical properties, and corrosion properties of AlCoCuFeNi HEA coatings prepared by gas tungsten arc (GTA) cladding on low-carbon substrates are examined and discussed. It was found that the coatings with and without ultrasonic treatment both have BCC dendrites and FCC interdendrites. Ultrasonic treatment increases phase fraction of BCC and narrow secondary dendrite arm spacing (SDAS), thereby increasing hardness, elastic modulus, and room-temperature creep resistance. Ultrasonic treatment suppresses dendritic segregation, thereby improving corrosion properties in 3.5 wt% NaCl solution. According to analysis, acoustic streaming has a greater impact compared with cavitation, which accelerates flow velocity and increases the cooling rate. This study preliminarily examines the effectiveness of ultrasonic treatment in suppressing segregation in HEA. [Display omitted] • AlCoCuFeNi high-entropy alloy coatings are prepared by ultrasonic assisted gas tungsten arc cladding. • Ultrasonic increases the phase fraction of BCC and refines microstructure. • Ultrasonic increase microhardness and improve corrosion performance. [ABSTRACT FROM AUTHOR]

Arc cladding high-entropy alloy (HEA) coatings have the advantages of low cost and flexibility. It exhibits economic value to increase the proportion of Fe element in HEA systems. As a result, low-cost AlCoCrFeNi (Fe content of 42.5 at.%, 44.9 at.%, 47.5 at.%, 50.4 at.%) HEA coatings are prepared by gas tungsten arc (GTA) cladding and their microstructure, mechanical properties, and corrosion properties are investigated by XRD, SEM, EBSD, microhardness, nanoindentation, OCP, potentiodynamic polarization, and EIS. The valence electron concentration (VEC) plays an important role in the formation of phase structure. With the increase of Fe content, the phase structure of coating alloys changes from BCC to BCC + FCC, and the morphology changes from equiaxed grains to a dendritic structure. Coating alloy with higher Fe content displays lower microhardness and more active creep deformation due to the higher FCC fraction. The dual-phase (BCC + FCC) structure induces galvanic corrosion and deteriorates the corrosion properties. This work contributes to the fabrication of large-thickness and large-area HEA coatings at a low cost and provides an experimental basis for Fe-rich HEA design. [Display omitted] • AlCoCrFeNi HEA coatings of high Fe content (42.5 at.% ~ 50.4 at.%) are prepared by gas tungsten arc cladding. • As Fe content increases, phases change from BCC to BCC + FCC, morphology changes from granular to dendritic. • As Fe content increase, hardness decrease and corrosion resistance deteriorate. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEA) are promising coating and structural materials for their excellent mechanical and corrosion properties, but the problems like coarse grain hinder the application. Ultrasonic treatment generally has the effect of grain refinement. Therefore, ultrasonic treatment is introduced to the process of gas tungsten arc (GTA) cladding AlCoCrFeNi HEA coatings. It was found that under ultrasonic treatment, the average grain diameter is refined by 70% (from 285 μm to 78 μm). The microhardness is increased by 20% (from 441 HV 1 to 532 HV 1), which is mainly attributed to the Hall-Petch relation. The corrosion performance in 3.5 wt% NaCl solution is also improved and the corrosion type changed from intergranular corrosion to uniform corrosion, which is mainly attributed to the increased segregation of Cr at grain boundaries. The mechanism of the impact of ultrasonic treatment on HEA coatings is discussed based on numerical simulation. Cavitation effect and acoustic streaming play a significant role in the dendritic fragmentation and consequent grain refinement. [Display omitted] • AlCoCrFeNi high-entropy alloy coatings are prepared by ultrasonic assisted gas tungsten arc cladding. • Ultrasonic treatment refined grain diameter by 70%, thereby increasing microhardness by 20%. • Ultrasonic treatment increases segregation of Cr in grain boundaries, thereby improving corrosion performance. • Cavitation effect and acoustic streaming both play a significant role in grain refinement. [ABSTRACT FROM AUTHOR]