Growth Interface Research Articles

Effect of GPa-level pressure on the microstructure and properties of Cu-8Ni-1.8Si alloy

Reducing or completely eliminating the reticular grain boundary phases in alloys is crucial for enhancing the mechanical and electrical properties of Cu-Ni-Si alloys with high nickel and silicon content (Ni + Si > 5wt.%). In this study, we investigated the microstructure, mechanical properties, and electrical conductivity of Cu-8Ni-1.8Si (wt.%) alloy prepared by high-pressure solidification (HPS) and subsequent aging treatment. The interfacial growth stabilizes as the pressure reduces the crystal growth rate, inhibits the diffusion of solute atoms, and increases the solute partition coefficient. The reticulated Ni31Si12 and granular Ni2Si phases disappear under 6GPa pressure, forming a complete Cu (Ni, Si) solid solution. After direct aging treatment, the precipitated phase of the HPS alloy is β-Ni3Si at the early stage of aging. At the peak aging state, β-Ni3Si and δ-Ni2Si phases coexist in the matrix. Additionally, the Avrami equations for the phase transition kinetics of HPS alloys at different aging temperatures were derived from the electrical conductivity data, and the strength contributions from solid solution strengthening and precipitation strengthening were calculated. The alloy aged at 450 °C exhibited the largest volume fraction and the smallest average size of precipitates, resulting in a more pronounced obstruction effect of nano precipitates on dislocation bypassing and demonstrating the best precipitation strengthening effect. At the peak aging states, the alloy's hardness reaches 367.5 HV, and the compressive yield strength reaches 788.2MPa. These results indicate that high pressure is an effective method to improve the solid solution degree of alloying elements and enhance the mechanical properties of Cu-Ni-Si alloys.

Popularity Bias in Correlation Graph-based API Recommendation for Mashup Creation

The explosive growth of the Application Programming Interfaces (APIs) economy in recent years has led to a dramatic increase in available APIs. Mashup development, a dominant approach for creating data-centric applications based on APIs, has experienced a surge in popularity. However, the vast array of choices poses a challenge for mashup developers when selecting appropriate API compositions to meet specific business requirements. Correlation graph-based recommendation approaches have been designed to assist developers in discovering related and compatible API compositions for mashup creation. Unfortunately, these approaches often suffer from popularity bias issues, leading to an inequality in API usage and potential disruptions to the entire API ecosystem. To address these challenges, our research begins with a theoretical analysis of the popularity bias introduced by correlation graph-based API recommendation approaches. Subsequently, we empirically validate the presence of popularity bias in API recommendations through a data-driven study. Finally, we introduce the p opularity b ias aware w eb A PI r ecommendation ( PB-WAR ) approach to mitigate popularity bias in correlation graph-based API recommendations. Experimental results over a real-world dataset demonstrate that PB-WAR offers the optimal tradeoff between accuracy and debiasing performance compared to other competitive methods.

An Eulerian-like interface-capturing approach for modeling the fouling process by crystallization

Calcium carbonate (CaCO3) is an inverse solubility salt commonly scaled in heat exchangers when the fouling mechanism by crystallization occurs. Several models have been proposed to predict the fouling behavior, considering the growth of fouling mass as the difference between deposition and removal rates. Despite the different alternatives suggested in the literature to approximate these rates, there has been limited discussion regarding the fouling layer growth interface capture within a continuous domain during the time-dependent crystallization process. Hence, in this work, we propose an Eulerian interface-capturing approach for modeling the fouling process by crystallization (EICAFC). This scheme will be implemented using the standard Galerkin Finite Element Method with linear interpolation polynomials. The EICAFC procedure will be outlined employing the Bohnet fouling model. Results about fouling thickness, mass accumulation, fouling resistance, and the EICAFC performance will be discussed.

Electro-assisted interfacial growth of biomimetic KFUPM-100 MOF membrane for ultrafast oil-water separation with breakthrough stability

Electro-assisted interfacial growth of biomimetic KFUPM-100 MOF membrane for ultrafast oil-water separation with breakthrough stability

Effects of the grain size and orientation of Cu on the formation and growth behavior of intermetallic compounds in Sn-Ag-Cu solder joints

The rapid development of semiconductor packaging technology has accelerated the applications of flip-chip bonding technology using fine-pitch micro bumps and Cu pillar bumps. These micro-bump systems are composed of metallic Cu and Sn. The properties of the Cu- and Sn-based bonding materials applied in these technologies have a significant effect on the mechanical properties and long-term reliability of micro-joints. This study focuses on the effects of the grain size and orientation of the Cu substrate on the formation and growth of intermetallic compounds (IMCs) at the Sn/Cu interface. The Cu substrate was annealed from 200 to 1000 °C to alter its grain size, which was measured via electron backscatter diffraction analysis. Sn-3.0Ag-0.5Cu (SAC) solder paste was printed onto the Cu substrate, and the Sn/Cu interfacial microstructure was observed by scanning electron microscopy and energy-dispersive X-ray spectroscopy after the reflow soldering process. A thin IMC formed on substrates with small grain sizes, whereas larger grain sizes resulted in the formation of thick and elongated IMCs. In addition, the IMC growth exhibited a specific directional preference in the (21̅1̅0) direction on substrates annealed at 1000 ℃. The effects of the Cu grain size and orientation on the interfacial reactions and growth of IMCs were compared and analyzed by observing IMCs formed at the SAC/Cu interface. Microstructural analysis revealed that controlling the Cu grain size and orientation significantly impacts the reliability of the solder joints. This study shows that the effect of grain size and orientation can be utilized to micro-solder joints, which can significantly enhance their mechanical strength and reliability.

(Invited) In-Situ Observation of SiC Solution Growth: Observation Principle and Effect of Al Addition to Si-Cr Solvent

BackgroundsSolution growth of SiC bulk single crystals has been studied as a potential method for growing high-quality crystals with keeping high growth rate. The use of Si-Cr alloy solvent has led to rapid growth rates, and reduction of dislocations using macrosteps has been reported. On the other hand, when the degree of supersaturation is increased to achieve high-speed growth, the distribution of supersaturation causes step bunching, which leads to solvent and polytype inclusions. Therefore, we have established an in-situ observation method at temperatures above 1300 °C to clarify various phenomena at the growth interface. This observation method is based on the transmission property of SiC against visible light. Bright-field observation using a white LED light enables us to obtain the step distributions at the interface, and internal interference observation using a He-Ne laser (632.8 nm) enables to measure the step height and growth rate. In this study, we evaluated temperature dependence of the optical absorption properties of the major SiC polytypes with the aim of enabling the identification of the polytypes during the in-situ observation method. We also focused on Al, which is known to suppress bunching when added in small amounts to the solvent, and investigated the effect of Al on the SiC solution growth interface by in-situ observation.Polytype identification during in-situ observationThe polytypes that easily occur at 1300-2000 °C are 3C, 4H, and 6H-SiC, each of which has its own band gap. Therefore, if the temperature dependence of the optical absorption property of each polytype is known, it is possible to determine the polytype from the observed image. Based on this, we measured the temperature dependence of the optical absorption properties of each polytype and evaluated the band gap. As a result, the band gap of each polytype decreased linearly with temperature, and was found to be larger in the order of 3C, 6H, and 4H-SiC in any temperature range. By referring to the optical absorption properties, it became possible to capture the distribution of different polytypes by using the difference in transmittance when they have a thickness of ~1 μm or more.Effect of Al addition to Si-Cr solvent on SiC growth interfaceIt is known that the solvent system has a significant effect on the step structure of the growth interface in terms of polytype inclusions and step bunching formation. Especially, addition of a small amount of Al is considered to have advantage in improving crystal quality. Therefore, in-situ observation of the growth interface on an on-axis 4H-SiC(000-1) at 1600 °C was performed using Si-40 mol%Cr and Si-40 mol%Cr-2 mol%Al solvents. Without Al, formation of step bunching was observed during the progress of step flow growth, which was induced by the small off-angle of the seed crystal. Eventually, the terrace expanded and bunching of the surrounding steps progressed, resulting in significant roughening of the interface. In contrast, with Al, the growth interface was covered by aligned steps, and step flow growth continued with steps of 10–20 nm in height. Therefore, it was found that Al prevents the formation of step bunching, leading to the suppression of macrostep formation.ConclusionsWe have established in-situ observation method of SiC solution growth interface for clarifying various phenomena at the growth interface. Polytype identification during the in-situ observation was proposed as a further technique, and the temperature dependence of the optical absorption properties of SiC polytypes were summarized as fundamental data. It was also revealed that the addition of Al to the Si-Cr solvent has an effect to suppress the formation of step bunching at the SiC growth interface.

(Invited) Advanced Virtual Sigesn Substrates for the Monolithic Integration of Novel Opto- and Nanoelectronics

In the past three decades, the ternary alloy semiconductor SiGeSn has evolved from a predicted direct semiconductor to a serious candidate for the realization of a myriad of interesting applications. The fields of application vary from novel transistor concepts 1–4 for up-coming processor generations to the already reported electrically pumped heterostructure laser diode 5–7, the last missing key component for the monolithically integrated optical on-chip communication on Si.This rise of SiGeSn originates mainly due to its ability of decoupling its bandgap from its lattice-constant by what it is predestined for the epitaxy of strain-reduced heterostructures and thus their monolithic integration on Si using the well-established Ge virtual substrate technology 8.However, utilizing the lattice-matching on Ge limits the epitaxy of strain-reduced heterostructures to an extremely narrow composition range of SiGeSn, for which a constant concentration ratio of Si to Sn of 3.67 needs to be fulfilled. In addition, the composition ranges of the more desirable direct bandgap SiGeSn require lattice-constants which are much larger than that of Ge, and thus a GeSn virtual substrate. Therefore, unlocking an even larger composition range necessitates a reliable technology for complete strain-relaxation of GeSn.However, up to this day, the complete strain-relaxation of GeSn proves itself quite challenging due to its limited thermal budget. In the case of chemical vapour deposition (CVD) based epitaxy, only partial relaxation occurs during growth, while the complete strain-relaxation is limited to post-growth methods like clearance etching for the strain relief of the resulting free-standing structures. Besides that, during the low-temperature molecular beam epitaxy (MBE) of GeSn, there is insufficient thermal energy for the formation of misfit dislocations. Therefore, MBE grown GeSn structures are typically pseudomorphic or show a very small degree of strain-relaxation. Nevertheless, various approaches, like post-growth annealing (PGA) have been investigated and reported to achieve partial relaxation up to 89 % 9. On top of that, partially relaxed GeSn buffers typically exhibit a surface roughness in the range of a few nanometres which is disadvantageous for high-performance heterostructures with individual layer thicknesses of a few tens of nanometres. A possible approach to counteract this problem is the introduction of surface smoothening steps such as using chemical mechanical polishing (CMP).In this work, we report the development of a combined fabrication scheme of MBE, PGA and CMP to achieve a GeSn double layer buffer stack with a final Sn concentration of 10 %, almost complete strain-relaxation and a surface roughness of ≈ 1.7 nm. A schematic overview of the process and the involved corresponding layer stacks is shown in Fig. 1a.All shown epitaxy experiments were performed in a 6” MBE system, where Si, Ge and Sn are used as matrix materials and B and Sb as dopants, respectively. In order to stabilize the Sn segregation in the low-temperature growth regime of SiGeSn at TS ≤ 200 °C, the substrate temperature is precisely measured and controlled in-situ using mid-infrared pyrometry 10.The development of the GeSn virtual substrates is based on the well-reported Ge virtual substrate on Si(001) 8, followed by an additional 100 nm thick Ge buffer layer. For the actual GeSn virtual substrate, a 400 nm thick GeSn layer with 6% Sn underwent PGA in a rapid thermal annealing system, subsequent to its growth. To achieve a best possible growth interface, a CMP step was used afterwards to smoothen the surface. Atomic force microscopy images of a final strain-relaxed GeSn virtual substrate with and without CMP are compared in Fig. 1b, where a nice cross-hatch pattern can be seen for the sample with CMP. The crucial step is then the growth continuation, which necessitates the effective removal of the native GeSn oxide. For this, a combination of wet etching via hydrogen chloride and a following in-situ soft thermal desorption at TS = 300 °C has proven itself as best solution 11. A final 400 nm thick GeSn layer with 10 % Sn completes the GeSn virtual substrate. This virtual substrate forms then the basis for the subsequent device growth, with the layer stack shown in Fig. 1c, and their fabrication using standard cleanroom processes, as described in an earlier report 11. The current voltage characteristics of an exemplary device with a diameter of 4 µm in Fig. 1d proves a good device functionality.Alongside to the latest results on the current development of GeSn virtual substrates using MBE, we provide an overview of past and future approaches for the realization of virtual SiGeSn substrates and their suitability for monolithically integrated SiGeSn heterostructures on Si. Figure 1

The Impact of Lithium Anode Interface on Capacity Fade in Polymer Electrolyte-Based Solid-State Batteries

This study investigates the Li stripping/plating morphology and failure mechanisms in full cells consisting of a solid polymer electrolyte (SPE) with two commercial Li anodes, Li chip and Li foil. The primary identified failure mechanism in the SPE is capacity fade, regardless of Li manufacturer or polymer thickness. While the cathode's role in capacity fade is evident, the Li anode significantly influences cycling performance, with Li foil cells cycling 50% longer than Li chip cells, a statistical difference. Postmortem scanning electron microscopy and X-ray photoelectron microscopy results attribute the Li Chip's faster capacity fade to a loss of contact and continuous growth of the solid electrolyte interface (SEI). Conversely, Li foil maintains consistent contact with the solid polymer, displaying a thin and stable SEI. Additionally, failure mechanisms between a gel electrolyte in previous work and the dry solid polymer electrolyte is compared.

Simulation of the Solid Electrolyte Interphase Layer in Lithium Metal Batteries – a Systematic Study

Instability of the anode-electrolyte interface and uncontrolled lithium (Li) dendrite growth pose serious safety concerns hindering the commercialization of high energy density Li metal batteries (LMBs). In particular, the Solid Electrolyte Interphase (SEI) layer is a key factor causing instability at the interface. The SEI layer is formed due to side reactions between Li, electrons, and electrolyte. When stable, this layer acts as a passivation layer that allows for transport of Li ions (Li+) to the anode while keeping the electrolyte and anode separated reducing the side reactions along the anode surface. However, following the initial growth of the SEI layer, the diffusion and reaction kinetics initiate dendrite growth, leading to the rupture of the SEI layer and exposure of fresh metallic Li. The high reactivity of Li metal results in continuous and rapid growth due to high reaction rates and fast kinetics. Finally, the SEI layer will reform over the exposed Li leading to excess electrolyte consumption causing permanent capacity loss and reduced coulombic efficiency.We present a systematic computational study of the various methods that are used to simulate the impact of the SEI layer, with varying level of complexity. Methods that were studied include varying reaction rates based on thinning and fracture of the SEI layer, a fixed SEI layer that possesses effective transport properties based on the porosity and tortuosity of the compact layer, the consideration of surface energy, and a competing current system that accounts for the ions consumed due to the parasitic SEI formation reaction.

Compact Modeling of Base Current High Injection Effect in SiGe HBTs

In bipolar transistor compact modeling, the forward mode base current typically consists of three components: space-charge recombination, back injection into the emitter, and neutral-base-recombination (NBR). At medium and high base-emitter voltages (VBE), the emitter back injection and NBR components dominate, and both increase exponentially with VBE. Deviation from the ideal behavior occurs at high VBE due to parasitic base and emitter resistance or self-heating.However, in many SiGe HBTs, standard compact models fail to capture experimentally observed IB-VBE characteristics, where the base current (IB) exhibits a high injection behavior that is more evident at lower collector-base voltages (VCB), as shown in Fig. 1. The simulation is done with Mextram 505.2 with resistance and self-heating parameters already calibrated. At a relatively low VBE of 0.72 V, the measured IB starts to bend downward compared to its typical behavior shown by the model, causing the increase of beta with VBE from 0.72 to 0.82 V. Parameter optimization cannot possibly fit silicon data and a new base current model is called for.Similar behavior has been observed by other groups and attributed to carbon-induced NBR [1]-[3]. Interestingly, the onset of this IB high injection occurs at a lower VBE than the onset of collector current (IC) high injection, which is typically due to Kirk's effect or quasi-saturation effect. Such IB high injection behavior also exhibits a complex VCB dependence. The change of IB-VBE slope is less visible at higher VCB due to self-heating, which increases IB.We present a recently developed compact model of base current that models this high-injection effect. The foundation of the high-injection effect model is an analytical expression of the neutral base recombination rate applicable to all injection levels derived from SiGe HBT NBR physics. Based on experimental data measured on devices with different geometries, we model both the area component and peripheral component with separate temperature coefficients. The area component is subject to neutral base width modulation modeled by the same parameters used for the Early effect. A quasi-saturation-induced component is included to model the NBR after the electrical neutral base pushes out at high current densities. The quasi-saturation component has its dedicated parameters to account for the NBR at the SiGe-base/Si-substrate epitaxial growth interface discussed in [4] and [5]. This component comes into play at higher VBE.Fig. 2 demonstrates the new model's capability in capturing the measured IB high injection behavior and its complex VCB dependence, as well as the much-improved fitting of the beta vs. VBE characteristics. The inclusion of the NBR high-injection effect in the base current model enables more accurate modeling of SiGe HBTs. The model has been implemented in Mextram 505.3 and later versions [6].

The snowball effect in electrochemical degradation and safety evolution of lithium-ion batteries during long-term cycling

Lifespan and safety are the most critical issues for the application of lithium-ion batteries (LIBs). During long-term service, the degradation mechanisms and safety evolution of LIBs remain unclear, posing significant obstacles to battery design and management. This study analyzes the electrochemical degradation mechanisms of LIBs under normal temperature cycling (NTC) and high-temperature cycling (HTC) conditions, linking these mechanisms to the evolution of battery safety. The findings reveal that during NTC, there is a “snowball effect” in performance degradation and safety evolution, leading to sudden death of battery and posing serious safety risks. The degradation pattern of LIBs during NTC and HTC is consistently dominated by the increase of internal resistance and the loss of lithium inventory (LLI). In the aging process, electrolyte consumption and the growth of the solid electrolyte interface (SEI) cause localized lithium plating on the anode, resulting in accelerated capacity decay. However, in batteries subjected to NTC, rapid accumulation of localized lithium plating can trigger a snowball effect, causing electrode deformation, internal short-circuit (ISC) and separator melting. These interacting catastrophic events form a vicious cycle, ultimately leading to battery sudden death and pose significant safety hazards. Additionally, thermal safety analysis reveals the correlation between thermal safety parameters and state of health (SOH), quantifying the thermal safety degradation caused by sudden death. Sudden death directly alters the evolution pattern of battery safety, leading to a severe decline in battery safety. These findings offer new insights into potential safety hazards associated with long-term use of LIBs.

SnPbInBiSb high-entropy solder joints with inhibited interfacial IMC growth and high shear strength

The rapid advancements in microelectronic devices towards miniaturization and multifunctionality have led to an increasing demand for solder joints that exhibit enhanced mechanical properties and reliability. This study focuses on investigating the high-shear strength of SnPbInBiSb/Cu high-entropy solder joints. The analysis encompasses the microstructure evolution, interfacial reactions, and shear behavior of these solder joints after reflowing at 180 °C. The study reveals the formation of very thin intermetallic compound (IMC) layers, specifically Cu6Sn5 and Cu3Sn, at the SnPbInBiSb/Cu interface with an average thickness of about 1.04 μm following a 10min reflow. Transmission electron microscopy (TEM) analysis illustrates the presence of nanoscale precipitates of InSn3 or Sn3Sb phases dispersed within the Cu6Sn5 IMC. The high mixing entropy of the SnPbInBiSb solder contributes to the suppression of the interfacial IMC growth rate during the reflow process. Notably, the shear strength and fracture behavior of the SnPbInBiSb high-entropy solder joints are significantly influenced by the thickness of the interfacial IMC. In particular, solder joints reflowed at 180 °C for 10 min exhibit a high shear strength of 102.4 MPa with a ductile fracture mode.

Effect of Soret diffusion on the growth of spherical crystals in supercooled alloy melts under oscillatory flow.

The growth of spherical crystals in binary alloy melts with thermal diffusion effects under oscillatory flow is investigated analytically. Using the multiple scale method, we derive approximate analytical solutions for both the crystal interface growth rate and the solute concentration. Our results demonstrate that the Soret effect significantly influences both the solute concentration near the crystal interface and the crystal growth rate. Specifically, with a positive Soret coefficient, the growth rate of spherical crystals in a binary dilute alloy melt decreases as the coefficient increases, while the solute concentration near the interface increases. In contrast, with a negative Soret coefficient, the growth rate of the spherical crystals increases as the coefficient decreases, and the solute concentration near the interface decreases. Additionally, the presence of oscillatory flow markedly promotes the grain refinement induced by the Soret effect.

Influence of substrate polarity on thermal stability, grain growth and atomic interface structure of Au thin films on ZnO surfaces

The influence of the polarity of ceramic substrates on the structural evolution of thin metal films during annealing at elevated temperatures is investigated, including the competing processes of solid state dewetting (SSD) and grain growth, as well as the atomic structure of the epitaxial interface. For this purpose, Au thin films on polar O-ZnO(0001‾) and Zn-ZnO(0001) surfaces are annealed at elevated temperatures and times. Whereas SSD dominates on the O-terminated surface, pronounced grain growth is observed on the Zn-terminated surface. The texture analysis revealed that up to 600 °C, both samples exhibit a fiber texture with slightly dominating Au(111)[110] || ZnO(0001)[112¯0] orientation relation (OR 2). At 800 °C, Au on Zn-ZnO exhibits a transformation to a mazed bicrystal structure with Au(111)[110] || ZnO(0001)[101¯0] orientation relation (OR 1). Comparison of various interface structures in density-functional theory (DFT) indicates that atomically sharp interfaces between the Au(111) films and the ideal bulk-truncated polar ZnO surfaces are energetically favored for both substrate polarities in excellent agreement with atomically resolved electron microscopy. Due to the larger period of the coincidence site lattice in OR 2, the corresponding interface can be described as semi-coherent with clearly separated misfit dislocations. In contrast, the much smaller period of the (approximate) coincidence site lattice in OR 1 leads to a largely incoherent interface with local reconstructions. However, in the experimental situation, even a small rotational deviation from the perfect OR 1 can introduce an interfacial screw dislocation network superimposed on the incoherent interface structure, effectively making the interface semi-coherent.

Improvement of mid-wavelength InAs/InAsSb nBn infrared detectors performance through interface control

We report our study to optimize the growth of mid-wavelength InAs/InAsSb nBn infrared detectors through interface control method with AlSb/AlAs superlattices as electron barrier. The dark current model was employed to investigate the dominant dark current mechanism at various operating temperatures. We extracted the minority carrier lifetime of InAs/InAsSb material grown by different interface growth methods. Electrical and optical characterizations indicated superior performance of the device grown by migration-enhanced epitaxy (MEE) with a 3 s As and Sb soak time. With −0.3 V applied bias and 150 K operating temperature, the optimal device shown a dark current density of 8.95 × 10−6 A/cm2 and peak specific detectivity of 7.12 × 1011 cm Hz1/2/W at 3.8 µm.

Dendrite-Free Lithium Batteries Enabled by an Artificial High-Dielectric Biopolymer Interface Layer.

Lithium (Li) metal batteries face challenges, such as dendrite growth and electrolyte interface instability. Artificial interface layers alleviate these issues. Here, cellulose nanocrystal (CNC) nanomembranes, with excellent mechanical properties and high specific surface areas, combine with polyvinylidene-hexafluoropropylene (PVDF-HFP) porous membranes to form an artificial solid electrolyte interphase (SEI) layer. The porous structure of PVDF-HFP equalizes the electric field near metallic lithium surfaces. The high mechanical modulus of CNC (6.2 GPa) effectively inhibits dendrite growth, ensures the uniform flow of lithium ions to the lithium metal electrode, and inhibits the growth of lithium dendrites during cycling. The synergy of high polarity β-phase poly(vinylidene fluoride) (PVDF) and CNC provides over 1000 h of stability for Li//Li batteries. Moreover, Li//LiFePO4 (LFP) full cells with this artificial protective layer perform well at 5 C, showcasing the potential of this film in lithium metal batteries.

Tailored micro-arc oxidation coatings to match with parylene for enhanced tribological performance of Ta-12W alloys

To improve the tribological properties of tantalum-tungsten alloys, dual-layer composite coatings are designed using micro-arc oxidation (MAO) and chemical vapor deposition (CVD) techniques. By adjusting the concentrations of NaOH and NaF additives as well as the oxidation mode (constant current/voltage) of MAO process, the microstructure and properties of underlying MAO layers are tailored for better matching with the top parylene layer, aiming to develop composite coatings capable of service under heavy loads. A comprehensive study is conducted to evaluate the effect of these parameters on the growth, microstructure, bond strength, and mechanical properties of MAO coatings, along with their subsequent impact on the friction and wear behavior under various loads for composite coatings. The findings reveal that increasing the concentration of either NaOH or NaF significantly increases the coating thickness, surface porosity, crystallinity, and hardness of MAO coatings, by promoting the spark discharge activities. However, distinct interfacial growth behavior is observed due to anionic effects caused by OH− and F−. The oxidation mode plays a crucial role in determining the mechanical quality of coatings; the constant voltage mode facilitates dense coatings with high adhesion due to its self-repairing mechanism. Furthermore, wear tests confirm that the enhanced mechanical properties and open-porosity of the MAO coatings markedly improve the tribological performance of composite coatings. This improvement is attributed to the excellent load-bearing capacity provided by hard MAO layers, as well as the anchoring and storage capabilities of the textural porous surfaces. The optimized composite coating demonstrates long-lasting low friction even under heavy loads up to 80 N.

Microstructure of ternary Sn-Bi-xCu alloy on mechanical properties, current endurance and corrosion morphology via cycling corrosion test

Low melting temperature of Sn-58 wt% Bi (SB) solders adding 0.5 wt% Cu (SB05C) and 1.7 wt% Cu (SB17C) concentrations were evaluated for the signal transmission in the 3D IC package. Microstructure combined with phase analysis and Pandat simulation were together with to explain the relationship among the mechanical property, electrical endurance and corrosion resistance. By Cu decoration, the presence Cu6Sn5 intermetallic compound (IMC) acts as heterogeneous nucleation sites to reduce surface free energy and generate fine Bi grain that resulted in higher hardness value. The power-law was used to explain the mechanism of interfacial IMC growth, both Cu6Sn5 and Cu3Sn formation were speculated to be volume diffusion control and surface reaction domination, respectively. The fracture morphology by shear testing indicates that earliest plastic deformation accompanied with brittle rupture were major factors due to the intergranular fracture and Cu6Sn5 compound induced bulk fracture. By cycling corrosion test (CCT), the lump shape of SnO2 by-product was found among solders at three cycling. After seven cycling, Sn phase has been completely corroded and Cu6Sn5 IMC began to be corroded forming circle shape of Cu2O but Bi phase still not be corroded among solders. In the electrical endurance, dense Cu6Sn5 dispersed in solder bulk and fine grain size were feasible to induce current crowding and joule heating, thus Cu deteriorated SB solders is easily failed.

Growth mechanism and SERS effect of Ag nanowire arrays prepared by solid-state ionics method

Solid-state ionic method has attracted more and more attention due to its simple operation and controllable preparation, but its growth mechanism is still uncertain. In this work, Ag nanowire (Ag NW) arrays prepared by solid-state ionics method at 5 μA impressed currents using fast ionic conductor RbAg4I5 films and different metal electrodes were reported. The conduction mode of Ag+ in RbAg4I5 films, the growth mechanism of Ag NW arrays prepared by solid-state ionics method and the effect of microscopic morphology on surface-enhance Raman scattering (SERS) performance were investigated. The results show that Ag nanoparticles (Ag NPs) with diameters from 40 nm to 70 nm were attached to the surface of Ag NW arrays with diameters of 80–150 nm prepared with different metal electrodes, which lead to Ag NW arrays have high surface roughness. The conduction velocity and stability of Ag+ in RbAg4I5 films are closely related to the morphology of Ag NW arrays. The irregular electrode interface and apical growth advantage resulted in the fractal dimension of Ag NW arrays prepared with Ag electrodes is 1.69 due to macroscopic dendritic structure. Ag NW arrays have excellent SERS performance due to the many Ag NPs attached to the surface of the closely aligned Ag NWs, the limit of detection (LOD) for Basic Fuchsin (BF) and Crystal Violet (CV) detected by Ag NW arrays SERS substrates prepared with Ag electrodes are as low as 10−11and 10−14mol/L, respectively. This paper provides a reference for the preparation method of metal nanostructures, Ag NW arrays have good potential for application in the field of trace analysis.

Numerical model for the solidification of a chondrule melt

In this study, we propose a novel numerical method to simulate the growth dynamics of an olivine single crystal within an isolated, multicomponent silicate droplet. We aimed to theoretically replicate the solidification textures observed in chondrules. The method leverages the phase-field model, a well-established framework for simulating alloy solidification. This approach enables the calculation of the solidification process within the ternary MgO–FeO–SiO2 system. Furthermore, the model incorporates the anisotropic characteristics of interface free energy and growth kinetics inherent to the crystal structure. Here we investigated an anisotropy model capable of reproducing the experimentally observed dependence of the growth patterns of the olivine single crystal on the degree of supercooling under the constraints of two-dimensional modeling. By independently adjusting the degree of anisotropies of interface free energy and growth kinetics, we successfully achieved the qualitative replication of diverse olivine crystal morphologies, ranging from polyhedral shapes at low supercooling to elongated, needle-like structures at high supercooling. This computationally driven method offers a unique and groundbreaking approach for theoretically reproducing the solidification textures of chondrules.