Interfacial Mixing Research Articles

Thermally induced reaction and transient hardening of miscible spinodoid alloys

Spinodoid alloys prepared by dealloying and deposition exhibit a bicontinuous dual-phase nanostructure with (semi-)coherent interfaces, resembling some features of the structure formed in spinodal decompostion. Composition fluctuation in such material and its spinodal-like hardening may then be tuned via thermally induced interdiffusion, even in undecomposable alloys. This paper studied the annealing behavior of miscible Cu/Au and Ag/Au spinodoid alloys with semi-coherent and coherent interfaces respectively. While the interdiffusion-dominated interfacial mixing occurs in both alloys, this process is interrupted in the Cu/Au alloys by a recrystallization-like reaction due to the large lattice mismatch between Cu and Au. We also found that interdiffusion does not monotonically soften these materials; instead, hardening can be observed in both alloys at the early stage of annealing, though further annealing eventually leads to softening. Thermally induced transient hardening is attributed to the formation of a diffuse Cu/Au or Ag/Au interface whose barrier strength to dislocation transmission is enhanced comparing to the sharp interface before annealing. Localized solid solution hardening and the dissociation of misfit dislocations within the diffuse interface might have led to the increase of interfacial barrier strength.

Influence of Friction Stir Additive Manufacturing Parameters on Dry Friction and Wear Properties of Al-Mg-Si Alloy's Built Surfaces Fabricated by Sheet Lamination

Abstract In this article, friction-stir additive manufacturing, a solid-state process for rapid fabrication of large components, is employed to investigate laminated Al-Mg-Si alloy blocks. The study delves into microstructural changes, hardness distribution, and wear behavior on two distinct surfaces using various parameters such as rotational speed (800 and 1200 rpm), traverse speed (41 and 82 mm/min), and a 50% pin overlap for block fabrication. Macrographs demonstrate the influence of adjacent toolpath overlap on layer integrity through interfacial mixing and consolidation of plastically deformed material. Within the overall stirred zone, re-stirring effects lead to refined grain formation and the dissolution of Mg2Si precipitates, resulting in an uneven micro-hardness distribution due to varying thermal cycles. Notably, specimens with a traverse speed of 41 mm/min exhibit reduced wear loss, attributed to microstructural changes that enhance resistance to plastic deformation during sliding, thereby improving tribolayer stability. This enhancement is attributed to increased hardness arising from refined grains and the strain hardening effect. Interestingly, the study finds that the horizontal surface of the fabricated blocks displays superior wear resistance compared to the vertical surface, due to the more homogeneous microstructure in individual layers. Further analysis using FESEM and EDS unveils the presence of glaze layers, oxide films, galling surfaces, grooving, trimming impacts, ploughing marks, and the accumulation of wear debris within wide pits and on worn-out pin surfaces. Scar morphology reveals that both abrasive and adhesive wear mechanisms contribute to volumetric losses in the specimens.

Non-hydrostatic simulation of two-layer density stratified flows over a sill

The topography between the ocean and marginal sea basins is often complex with narrow channels and shallow sills. Two-layer exchange flows are usually observed in the channels with internal waves and small-scale instabilities at the interface. A high-resolution, non-hydrostatic model (NHWAVE) is used to simulate the interfacial mixing processes. Excellent agreement with the experiment data is obtained, especially for the simulation of vertical velocity and internal wave dispersion. In the mixing processes, turbulent coherent structures vary from spanwise uniform vortices to full 3D vortices with random shapes of spanwise and streamwise vortices. These vortices correspond to the surface velocity divergence with wave-like perturbations and the crests of the vortices associate with the down zero crossings of the divergence. The non-hydrostatic effect is also analyzed by an aspect ratio. The results show that the most obvious non-hydrostatic areas are located at the lee side of the sill, ranging from x = 0–1 m. And the effect of non-hydrostatic is more significant with larger values of the vertical velocity gradient.

High-amplitude effect on Richtmyer–Meshkov instability at a single-mode heavy–light interface

An experimental study is conducted to explore the high-amplitude effect on Richtmyer–Meshkov instability (RMI) at a single-mode heavy–light interface. A wide range of scaled initial amplitude (ka0, where k and a0 are perturbation wavenumber and initial amplitude, respectively) is considered. Qualitatively, nonstandard (standard) indirect phase inversion occurs in experiments with high (low and moderate) ka0. The nonstandard indirect phase inversion exhibits a complex process, and the interface mixing width does not reduce to near zero. Quantitatively, the linear model poorly (accurately) predicts the post-phase-inversion linear amplitude growth rate when ka0 is high (low and moderate). Additionally, a representative theoretical reduction factor fortuitously evaluates the high-amplitude effect on the post-phase-inversion linear amplitude growth rate well. The high-amplitude effect significantly alters the nonlinear evolution law, which differs from the case of RMI at a light–heavy interface. None of the considered nonlinear models can accurately predict the amplitude evolution under all ka0 conditions, regardless of whether their expressions are related to ka0 or not. Based on the current experimental results, an empirical nonlinear model is proposed to describe RMI at a single-mode heavy–light interface across a wide range of ka0 conditions.

Ionomer Interfacial Behavior from Molecular Dynamics Simulations: Impact of Ion Content on Interfacial Structure and Mixing

Ionomer Interfacial Behavior from Molecular Dynamics Simulations: Impact of Ion Content on Interfacial Structure and Mixing

Simultaneous measurements of kinetic and scalar energy spectrum time evolution in the Richtmyer–Meshkov instability upon reshock

The Richtmyer–Meshkov instability (Richtmyer, Commun. Pure Appl. Maths, vol. 13, issue 2, 1960, pp. 297–319; Meshkov, Fluid Dyn., vol. 4, issue 5, 1972, pp. 101–104) of a twice-shocked gas interface is studied using both high spatial resolution single-shot (SS) and lower spatial resolution, time-resolved, high-speed (HS) simultaneous planar laser-induced fluorescence and particle image velocimetry in the Wisconsin Shock Tube Laboratory's vertical shock tube. The initial condition (IC) is a shear layer with broadband diffuse perturbations at the interface between a helium–acetone mixture and argon. This IC is accelerated by a shock of nominal strength Mach number $M = 1.75$ , and then accelerated again by the transmitted shock that reflects off the end wall of the tube. An ensemble of experiments is analysed after reshock while the interface mixing width grows linearly with time. The kinetic and scalar energy spectra and the terms of their evolution equation are calculated and compared between SS and HS experiments. The inertial range scaling of the scalar power spectrum is found to follow Gibson's relation (Gibson, Phys. Fluids, vol. 11, issue 11, 1968, pp. 2316–2327) as a function of Schmidt number when the effective turbulent Schmidt number is used in place of the material Schmidt number that controls equilibrium scaling. Further, the spatially integrated scalar flux follows similar behaviour observed for the kinetic energy in large eddy simulation studies by Zeng et al. (Phys. Fluids, vol. 30, issue 6, 2018, 064106) while the spatially varying scalar flux exhibits back scatter along the centre of the mixing layer and forward energy transfer in the spike and bubble regions.

Deposition of TiNi thin films on Ni(001) substrate using molecular dynamics simulation

This paper investigates the effect of incident energy and substrate temperature on the morphological and microstructural properties of TiNi thin films deposited on Ni substrate. The detailed analysis of surface morphology, the interface intermixing, density, and the voids in TiNi thin films was performed by molecular dynamics simulation combined with the second nearest-neighbor modified embedded-atom method interatomic potential (2 NN MEAM). The results indicate that higher incident energy and substrate temperature affect morphological properties of TiNi thin film. When the incident energy ranges from 0.1 to 10 eV, the surface roughness initially increases before eventually decreasing. Regarding the substrate temperature, the roughness decreases initially from 300 K to 700 K, but beyond 700 K, it begins to increase again. In addition, the interface mixing analysis was also affected by incident energy. It is found that, the thickness of the mixing interface was increased as the incident energy increase. This suggests that the growth mode changes from epitaxial to mixing. When the incident energy is higher than 10 eV, the diffusion rate of Ti atoms in the substrate layers is higher than that of Ni atoms. Conversely, at the surface of thin film, the concentration of Ni atoms is higher than that of Ti atoms. However, the substrate temperature has no significant effect on the change in interface thickness. The density of the TiNi thin films shows a significant dependence on the incident energy, but not affected by the substrate temperature. In addition, the result reveal that the increasing both the incident energy and the thickness of thin films reduces the concentration of voids and vacancies.

Friction surfacing of aluminum to steel: Influence of different substrate surface topographies

In the present study, AA6082 aluminium is deposited onto AISI 4140 steel substrates via friction surfacing (FS). Aiming to understand the influence of substrate surface for the bonding mechanism during the plasticising as well as the deposition phase, three different surface topographies have been manufactured via grinding and machining. Subsequently, FS process parameter dependencies on the deposits have been investigated. The resulting optical appearance, geometry and microstructure of the deposits have been studied. A deeper surface topography was found to facilitate plasticising and therefore FS layer deposition. Defect-free layer-to-substrate (LTS) joints have been generated for all topographies showing a fine-grained recrystallized microstructure as well as flow lines in the AA6082 deposits following closely the substrate surface topography, whereas no metallurgical changes in the AISI4140 substrates have been detected. At the LTS interfaces, a correlation of flow lines to an increased occurrence of high angle grain boundaries is identified. Appearance, geometries and grain size ratios of the AA6082 deposits show a dependency on substrate surface topography. Although complete bonding was achieved in the LTS joints, no distinct diffusion zone or interfacial mixing was observed. Mechanical interlocking on the micro scale was detected only for the samples with ground substrate surfaces.

Tuning in linear and nonlinear optical parameters by interfacial mixing of Sb/Ag2Se bilayer thin films under annealing at different temperatures for optoelectronic applications

Semiconducting materials have found enormous interest due to their immense applicability in various optoelectronics fields. In the current report, Sb/Ag2Se bilayer thin film was prepared through thermal evaporation techniques. The thickness of the thin film was 636 nm, where Sb layer of 20 nm was deposited over 616 nm layer of Ag2Se. Bilayer film was annealed at various temperatures for 2hr. The structural study of the material shows the presence of Ag2Se orthorhombic phase. The crystallinity of the material gradually increased with the annealing process. The surface morphology of the material reveals the enhancement in the porosity of the material after annealing. Transmission spectra show a decreased pattern after the annealing process. The optical study showed a red shift in absorption edge and reduced optical bandgap. This may be for the increase in the width of the localised states. Other linear parameters such as skin depth, extinction coefficient and optical density were also estimated from the observed data. The high-frequency dielectric constant and static refractive index increased with annealing temperature, satisfying the Moss rule. 1st and 3rd order non-linear susceptibilities were increased from 0.587 esu to 0.633 esu and 2.02 × 10−11 esu to 2.02 × 10−11 esu, respectively. The surface wettability study of the material shows a transition from hydrophobic to hydrophilic nature. Thiese properties made the sample possible application for self -cleaning material for solar panels or other devices. The observed optical properties of the material prove its applicability to other optoelectronic devices.

Surface growth, inner defects and interface mixing of Cr coating on Zr alloy irradiated by 5 MeV protons at 400°C

Surface, inner and interface damages of Cr coatings irradiated by 5 MeV protons were characterized by XRD, SEM, TEM and nanoindentation in this work. After irradiation, a Cr7C3 growth layer with refined grains was formed on the surface due to the separation and redeposition of diffused Cr atoms. Irradiation-induced defects in the Cr coatings were voids, dislocations, and bubble-vacancies complexes. Importantly, irradiation softening was found for the arc-ion plated Cr coating, which should be due to the deformation recovery and recombination of inherent sinks and irradiation defects. At the coating-substrate interface, the ZrCr2 C14 phase, a multilayered interface and the preferential diffusion were found, meaning chained or layered Cr atoms may dominate the interface diffusion. In mechanism, formation mechanisms of irradiation defects are analyzed and the irradiation-enhanced diffusion, ballistic collision and the sharpening effect are employed to explain the interface mixing. A correlation coefficient of the anisotropic diffusion is proposed in the Cr flux equation for explaining the (110)-dominated diffusion. The results show that irradiation effects of coatings depend on the inherent defects and preferred orientation produced in the preparation process of coatings.

Current-carrying wear behavior and the interface evolution of the Cu/Al tribological pair

Cu/Al tribological pairs play a crucial role in maintaining the efficient operation of a wide range of engineering components. However, their durability is often compromised by wear-induced damage, which involves the accumulation of material at the Cu/Al friction interface. This study investigates the intricate wear behavior of Cu/Al tribological pairs under electrical current, with a specific emphasis on material transfer events occurring at the interface. Our findings reveal that the applied electric current exerts a lubricating effect on the sliding contact friction, resulting in reduced adhesive wear. However, it concurrently exacerbates fatigue-induced delamination, abrasive wear, and electrical wear. Through detailed analysis of interface temperatures and microstructure characterizations, we demonstrate that Al deposit adhesion occurs through interfacial metal mixing and nanoscale diffusion in the presence of only mechanical friction. Conversely, at high electrical currents, interfacial melting transpires, resulting in robust adhesion facilitated by the formation of an intermetallic compound. Our findings offer valuable insights into the microscopic adhesion events occurring in Cu/Al tribological pairs and provide guidance for developing innovative coating systems aimed at reducing material deposition in Cu/Al current-carrying friction interfaces.

Velocity Fluctuations Spectra in Experimental Data on Rayleigh–Taylor Mixing

Rayleigh–Taylor (RT) interfacial mixing plays an important role in nature and technology, including atmospheric flows. In this work, we identify the physics properties of Rayleigh–Taylor mixing through the analysis of unprocessed experimental data. We consider the fluctuations spectra of the specific kinetic energy of each of the velocity components, and identify their spectral shapes, by employing the group theory guided foundations and the rigorous statistical method. We find the spectral shape parameters, including their mean values and relative errors, and apply the Anderson–Darling test to inspect the residuals and the goodness-of-fit. We scrupulously study the effect of the fitting window and identify, for each velocity component, the best fit interval, where the relative errors are small and the goodness of fit is excellent. We reveal that the fluctuations spectra in RT mixing experiments can be described by a compound function, being a product of a power-law and an exponential. The data analysis results unambiguously discovered the dynamic anisotropy and the dynamic bias of RT mixing and displayed the necessity to improve the design of experiments on RT mixing.

Highly efficient organic light emitting diodes fabricated by solution process with new hole transport materials cross-linked at 120 °C

This work presents a rational design strategy for the synthesis of three thermal cross-linkable polystyrene-based hole transport copolymers (PPPIC-co-PBCB, PPIC-co-PBCB, PBIC-co-PBCB) by a simple free radical polymerization of planar structured indenocarbazole (IC)-based monomers having extended conjugated length and thermal cross-linkable benzocyclobutene (BCB). The materials show an extremely low cross-linking temperature of 120 °C and outstanding hole mobility of 1.01⨯10−2 cm2V−1s−1 at 4.0⨯105 Vcm−1. This value is one of the highest mobilities reported for thermal cross-linked hole transport materials (x-HTMs) in the literature. The preferred horizontal orientation of transition dipole moment (TDM), which is hardly obtained in spin coated film, was successfully achieved, and used for charge transport analysis. Herein, we also confirmed that the cross-linking reaction in our x-HTMs did not have any negative effect on the mobility of the layer, a correct method for mobility calculation from the space-charge limited current (SCLC) model was suggested, and the extension of interface mixing was also estimated for the first time. Furthermore, solution-processed organic light-emitting diode (s-OLED) device employing PPPIC-co-PBCB as HTM shows ultra-efficient performance of 130.5 cdA−1 and 37.3 % external quantum efficiency. To the best of our knowledge, this result is also one of the best efficiencies for phosphorescent s-OLEDs reported. The synthetic strategy for the polymers is also very simple with the cross-linkable monomers attached to the polystyrene backbone.

Ion Irradiation-Induced Interface Mixing and the Charge Trap Profiles Investigated by In Situ Electrical Measurements in Pt/Al2O3/ β-Ga2O3 MOSCAPs

In situ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{I}$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{V}$</tex-math> </inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{C}\!\!-\!\!\textit{V}$</tex-math> </inline-formula> measurements were performed during the 120 MeV Au <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{9+}$</tex-math> </inline-formula> ion irradiation on the Pt/Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $</tex-math> </inline-formula> -Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> , metal–oxide–semiconductor capacitors (MOSCAPs), to comprehend the swift heavy ion (SHI)-induced effects at the interface and in the device performance. At a maximum fluence of 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{12}}$</tex-math> </inline-formula> ions/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{2}}$</tex-math> </inline-formula> , the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{I}-\!\textit{V}$</tex-math> </inline-formula> data showed a rise in the reverse leakage current by four orders of magnitude compared to the pristine device. The trap level (below the conduction band of Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}\text{)}$</tex-math> </inline-formula> from Poole–Frenkel emission exhibits a variation from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 1.1 to 0.91 eV. The conduction band offset <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text{(}\phi }_{\textit{B}}\text{) }$</tex-math> </inline-formula> of Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $</tex-math> </inline-formula> -Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> changes from 1.48 to 1.25 eV as estimated under the Fowler–Nordheim tunneling mechanism. In situ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{C}\!\!-\!\!\textit{V}$</tex-math> </inline-formula> measurements show a significant shift in the flat band voltages and increased oxide in the border and interface due to charge trapping. The X-ray photoelectron spectroscopy (XPS) measurements of Al 2p and O 1s core levels revealed the pre-existing oxygen defects in Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> , which increase with fluence. The deconvoluted peaks of Al 2p at 74.6 eV designated to Al-sub oxide and the O 1s peak variation in the FWHM signifies the increase in the O defects. Cross-sectional transmission electron microscopy (XTEM) measurements on the irradiated device (at 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{12}}$</tex-math> </inline-formula> ions/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{2}}\text{)}$</tex-math> </inline-formula> revealed a modulated interface of Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> / <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $</tex-math> </inline-formula> -Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> and the formation of an interlayer of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 4 nm Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{y}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{z}}$</tex-math> </inline-formula> . The scanning transmission electron microscope (STEM)-based high-angle annular dark-field imaging (HAADF) energy-dispersive X-ray spectroscopy (EDS) mapping revelation and the depth profiles of XPS data confirm the formation of an Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{y}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{z}}$</tex-math> </inline-formula> interlayer.

Invariant forms and control dimensional parameters in complexity quantification

Non-equilibrium dynamics is omnipresent in nature and technology and can exhibit symmetries and order. In idealistic systems this universality is well-captured by traditional models of dynamical systems. Realistic processes are often more complex. This work considers two paradigmatic complexities—canonical Kolmogorov turbulence and interfacial Rayleigh-Taylor mixing. We employ symmetries and invariant forms to assess very different properties and characteristics of these processes. We inter-link, for the first time, to our knowledge, the scaling laws and spectral shapes of Kolmogorov turbulence and Rayleigh-Taylor mixing. We reveal the decisive role of the control dimensional parameters in their respective dynamics. We find that the invariant forms and the control parameters provide the key insights into the attributes of the non-equilibrium dynamics, thus expanding the range of applicability of dynamical systems well-beyond traditional frameworks.

On asymmetric compound open channel flows with two distinct width floodplains: revisiting interfacial mixing layer and flow structures

On asymmetric compound open channel flows with two distinct width floodplains: revisiting interfacial mixing layer and flow structures

Effect of texture on 4H–SiC substrate surface on film growth: A molecular dynamics study

An investigation is conducted in this paper of the effect of different textured substrates on the growth of film. Meanwhile, a comparison of film quality with that of non-textured substrate is carried out. Results show that different textured substrates produce different dislocation morphologies, while the surface morphology is closely related to the substrate. There is less dislocation density and minimal surface roughness in the film with groove textured-[11‾00] substrate than in the film without the textured substrate. Interface mixing occurs in the deposition of film, resulting in an oscillatory behavior of the internal stress. The film with groove textured-[11‾00] substrate has a lower defect volume fraction and a higher film density than the film on non-textured substrate. Further, the groove textured-[11‾00] has a lower interface energy, which provides a good basis for the growth of the deposited film. The study of this work further reveals the role of different substrate patterns in regulating the crystal quality of 4H–SiC film, which provides guidance for the design of substrate patterns.

Numerical Study on Interfacial Structure and Mixing Characteristics in Converter Based on CLSVOF Method

The blowing flow is a key factor in molten bath stirring to affects the steel-bath interface fluctuation and chemical reaction in the top-bottom-blowing converter. The Volume of Fluid (VOF) method is widely used to capture the gas-liquid interface. However, some limitations exist in dealing with the interface curvature and normal vectors of the complex deformed slag-bath interface. The Coupled Level-Set and Volume of Fluid (CLSVOF) method uses the VOF function to achieve mass conservation and capture interface smoothly by computing the curvature and normal vector using the Level-Set function to overcome the limitations in the VOF model. In the present work, a three-dimensional (3D) transient mathematical model coupled CLSVOF method has been developed to analyze the mixing process under different injection flow rates and bottom-blowing positions. The results show that when the bottom-blowing flow rate increases from 0.252 kg/s to 0.379 kg/s, the mixing time in the molten bath gradually decreases from 74 s to 66 s. When the bottom-blowing flow rate is 0.252 kg/s, it is recommended to distribute the outer bottom-blowing position on concentric circles with Dtuy,2/D2 = 0.33.

Influence of Ni interlayer on hydrogen absorption and cyclicity in Gd thin films

The Pd/Gd bilayers and Pd/Ni/Gd trilayers were prepared onto glass substrates by magnetron sputtering. Detailed XPS in-situ studies of the Pd/Gd bilayers allowed to estimate the thickness of the mixed layer at about 4 nm. Further studies showed that the additional Ni interlayer can significantly reduce the interface mixing during the deposition process, leading to the formation of a rather narrow Ni–Gd interface. The structure of the obtained layers before and after the hydrogenation was examined by the standard X-ray diffraction method. The hydrogenation kinetics was studied in-situ at room temperature and pressure up to 1 bar using simultaneous measurements of resistivity and optical transmittance. Furthermore, hydrogen absorption by electrochemical method was monitored using optical transmittance. It was found that the use of an additional 4 nm Ni layer significantly improved the cyclicity of the hydrogen absorption/desorption from the electrolyte, while maintaining low switching time (10 s).

Optimization of interfacial mixing for thermal transport along Si/Ge heterostructures: A molecular dynamics study

Interfaces can play critical roles in the dissipation of heat, generated during the electronic nanodevices operation. Therefore, engineering of the interfacial thermal resistance is a key factor in the thermal management design of nanoelectronics. In this research, the engineering of the interfacial thermal resistance of silicon/germanium heterostructure is explored, by varying the content of silicon or germanium atoms at the interphase (mixing region). For this goal, we conducted systematic non-equilibrium molecular dynamics simulations. For a specific interphase length, it is noticeably predicted that the interfacial thermal resistance versus the percentage of germanium atoms shows an optimal minimum value. By substituting germanium atoms with silicon atoms, but with preserving their atomic mass, it is interestingly shown that the interfacial thermal resistance increases significantly, although the optimal value for the interfacial thermal resistance is still observable. By altering the length of the interphase region and the samples’ temperature (300 and 600 K), the optimal interfacial thermal conductance in terms of the percentage of germanium atoms in the mixing region was also detectable. The findings of this work can be useful in the thermal management engineering of nanodevices, especially in nanoelectronics.