Microstructure evolution and strengthening mechanism of CoCrFeMnNi HEA/Zr-3 brazed joints reinforced by fine-grained BCC HEA and HCP Zr

In the pursuit of manufacturing intricate components for the nuclear industry,we developed a novel Zr_(63.2)Cu_(36.8)(wt.%)alloy via vacuum melting for brazing applications involving equiatomic high-entropy alloys(HEA)of CoCrFeMnNi and zircaloy(Zr-3).We systematically investigated the influence of various brazing parameters on microstructure evolution and shear properties.Furthermore,we established a com-prehensive understanding of the relationship between the lattice structure of interfacial products,residual stress,and fracture behavior in HEA/Zr-Cu/Zr-3 joints.Our findings revealed that under specific conditions(1010℃for 10 min),the reaction products in HEA/Zr-Cu/Zr-3 joints consisted of lamellar HEAP/lamellar Zr(Cr,Mn)_(2),granular(Zr,Cu)/Zr_(2)(Cu,Ni,Co,Fe),bulk Zr(Cr,Mn)_(2),and Zrss.With increasing temperature and prolonged holding time,the layered HEAP and Zr(Cr,Mn)_(2)phases adjacent to the HEA substrates thick-ened,while the relative amounts of Zr_(2)(Cu,Ni,Co,Fe)decreased,with a remarkable increase in ductile Zrss.Growth kinetics analysis of the reaction layer and EBSD analysis indicated that the HEAP phases exhibited a lower growth rate compared to the Zr(Cr,Mn)_(2)layer during brazing,and both phases exhibited random grain orientations.Particularly noteworthy was the precipitation of(Zr,Cu)within the layered Zr(Cr,Mn)_(2),which increased and coarsened with higher temperatures and extended durations.Finite element analysis and TEM analysis revealed higher residual stresses at the non-coherent Zr(Cr,Mn)_(2)/HEAP interface with a lattice mismatch of 40.6%.The body-centered cubic(BCC)structural HEAP,composed of fine grains,effectively mitigated the concentrated residual stresses due to its superior plasticity.Moreover,micro-nanoscale close-packed hexagonal(HCP)precipitates(Zr,Cu)were distributed within the brittle Zr(Cr,Mn)_(2)phases,contributing to the overall strength improvement of the joints.Consequently,high-quality HEA/Zr-3 joints were achieved,featuring a maximum strength of 172.1 MPa,equivalent to approximately 62.6%of the yield strength of Zr-3.These results highlight the potential of Zr_(63.2)Cu_(36.8)(wt.%)alloys in advanced brazing applications.

Growth Mechanism of Microcrystalline Silicon Films by Scaling Theory and Monte Carlo Simulation

Hydrogenated microcrystalline silicon （~c-Si：H） films with a high deposition rate of 1.2nm/s were prepared by hot-wire chemical vapor deposition （HWCVD）. The growth-front roughening processes of the μc-Si..H films were investi- gated by atomic force microscopy. According to the scaling theory, the growth exponent β≈0.67, the roughness exponent α≈0.80,and the dynamic exponent 1/z = 0.40 are obtained. These scaling exponents cannot be explained well by the known growth models. An attempt at Monte Carlo simulation has been made to describe the growth process of μc-Si： H film using a particle reemission model where the incident flux distribution,the type and concentration of growth radical, and sticking,reemission,shadowing mechanisms all contributed to the growing morphology.

Numerical investigation of the deformation mechanism of a bubble or a drop rising or falling in another fluid

A numerical method for simulating the motion and deformation of an axisymmetric bubble or drop rising or falling in another infinite and initially stationary fluid is developed based on the volume of fluid （VOF） method in the frame of two incompressible and immiscible viscous fluids under the action of gravity, taking into consideration of surface tension effects. A comparison of the numerical results by this method with those by other works indicates the validity of the method. In the frame of inviseid and incompressible fluids without taking into consideration of surface tension effects, the mechanisms of the generation of the liquid jet and the transition from spherical shape to toroidal shape during the bubble or drop deformation, the increase of the ring diameter of the toroidal bubble or drop and the decrease of its cross-section area during its motion, and the effects of the density ratio of the two fluids on the deformation of the bubble or drop are analysed both theoretically and numerically.

Recent progresses in the suppression method based on the growth mechanism of lithium dendrite

Lithium secondary batteries（LSBs） with high energy densities need to be further developed for future applications in portable electronic devices, electric vehicles, hybrid electric vehicles and smart grids. Lithium metal is the most promising electrode for next-generation rechargeable batteries. However, the formation of lithium dendrite on the anode surface leads to serious safety concerns and low coulombic efficiency.Recently, researchers have made great efforts and significant progresses to solve these problems. Here we review the growth mechanism and suppression method of lithium dendrite for LSBs’ anode protection. We also establish the relationship between the growth mechanism and suppression method. The research direction for building better LSBs is given by comparing the advantages and disadvantages of these methods based on the growth mechanism.

Growth mechanism of reinforcements in in-situ synthesized (TiB+TiC)/Ti composites

The growth mechanism of reinforcement in in situ synthesized (TiB+TiC)/Ti composites was investigated. The results show that reinforcements nucleate and grow in a way of dissolution precipitation. The morphologies of reinforcements are closely related to the solidification paths and crystal structure of reinforcements. TiB, as a reinforcement, is liable to grow along [010] direction and forms in short fibre shape due to its B27 structure, whereas primary TiC is liable to form composition undercooling and grow in dendritic shape. TiC phases precipitated in binary eutectic and ternary eutectic reactions grow in equiaxial shape. The addition of aluminum element refines TiB and TiC particles, and makes TiC reinforcements grow into the equiaxial particles easily. The addition of graphite adjusts the solidification paths and forms more TiC with dendritic shape. [

The mechanisms of grain growth of Mg alloys:A review

Grain growth directly influences the plasticity and strength of Mg alloys.As the grain size decreases from the microscale to the nanoscale,the plasticity of Mg alloys continually increases,whereas the strength first increases and later decreases.These trends are observed because the plastic deformation mechanism changes from dislocation–twinning dominance to grain boundary dominance.In this study,the factors influencing grain growth,such as the temperature of plastic deformation/annealing,second-phase particles and solute atoms,are examined to aid effective control of the grain size.Additionally,the mechanisms of grain growth,typically induced by strain and thermal activation,are clarified.Strain-induced grain boundary migration is attributable to the difference in the strain energy stored in adjacent grains with high-density dislocations.Heat-induced grain boundary migration is driven by the difference in the energy of the grain boundary/subgrain boundary and boundary curvature.Abnormal grain growth can be induced by anisotropy of the strain energy,anisotropy of the grain boundary mobility,depinning of the second phase and high misorientation gradient.

Origin and growth mechanisms of strike-slip faults in the central Tarim cratonic basin, NW China

Through fault structure analysis and chronology study, we discuss the origin and growth mechanisms of strike-slip faults in the Tarim Basin.(1) Multiple stages strike-slip faults with inherited growth were developed in the central Tarim cratonic basin. The faults initiation time is constrained at the end of Middle Ordovician of about 460 Ma according to U-Pb dating of the fault cements and seismic interpretation.(2) The formation of the strike-slip faults was controlled by the near N-S direction stress field caused by far-field compression of the closing of the Proto-Tethys Ocean.(3) The faults localization and characteristics were influenced by the pre-existing structures of the NE trending weakening zones in the basement and lithofacies change from south to north.(4) Following the fault initiation under the Andersonian mechanism, the strike-slip fault growth was dominantly fault linkage, associated with fault tip propagation and interaction of non-Andersonian mechanisms.(5) Sequential slip accommodated deformation in the conjugate strike-slip fault interaction zones, strong localization of the main displacement and deformation occurred in the overlap zones in the northern Tarim, while the fault tips, particularly of narrow-deep grabens, and strike-slip segments in thrust zones accumulated more deformation and strain in the Central uplift. In conclusion, non-Andersonian mechanisms, dominantly fault linkage and interaction, resulted in the small displacement but long intraplate strike-slip fault development in the central Tarim Basin. The regional and localized field stress, and pre-existing structures and lithofacies difference had strong impacts on the diversity of the strike-slip faults in the Tarim cratonic basin.

Synthesis and growth mechanism of SiC/SiO2 nanochains by catalyst-free thermal evaporation method in Ar/CO atmosphere

SiC/SiO2 nanochains were synthesized on a carbon fiber substrate by a catalyst-free thermal evaporation method in the Ar/CO atmosphere.X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and transmission electron microscopy(TEM)revealed that the as-synthesized SiC/SiO2 nanochains are composed of single-crystalline SiC nanowires and amorphous SiO2 beads.The introduction of CO can promote the formation of SiO2,so that the SiC/SiO2 nanochains are subsequently formed during cooling.In addition,the photoluminescence spectrum of SiC/SiO2 nanochains showed a broad emission peak at around 350 nm,which is ascribed to the oxygen discrepancy in the SiO2 beads as well as the SiC/SiO2 interfacial effect.These findings can provide guidance for further study of the vapor growth of 1D SiC-based materials.

Understanding the growth mechanisms of metal-based core–shell nanostructures revealed by in situ liquid cell transmission electron microscopy

Metal-based core-shell nanostructures have garnered enduring interest due to their unique properties and functionalities.However,their growth and transformation mechanisms in liquid media remain largely unknown because they lack direct observation of the dynamic growth process with high spatial and temporal resolution.Developing the in situ liquid cell transmission electron microscopy(TEM)technique offers unprecedented real-time imaging and spectroscopy capabilities to directly track the evolution of structural and chemical transformation of metal-based core–shell nanostructures in liquid media under their working condition.Here,this review highlights recent progress in utilizing in situ liquid cell TEM characterization technique in investigating the dynamic evolution of material structure and morphology of metal-based core–shell nanostructures at the nano/atomic scale in real-time.A brief introduction of the development of liquid cells for in situ TEM is first given.Subsequently,recent advances in in situ liquid cell TEM for the fundamental study of growth mechanisms of metal based core–shell nanostructures are discussed.Finally,the challenge and future developments of metalbased core–shell nanostructures for in situ liquid cell TEM are proposed.Our review is anticipated to inspire ongoing interest in revealing unseen growth dynamics of core–shell nanostructures by in situ liquid cell TEM technique.

On the Mechanism of Evolution for Enterprise＇s Sustainable Growth Based on the Theory of Self-organization

The capabilities of industry, technology, institution and market power form the model of four-capability structure for enterprise＇s sustainable growth. The firm＇s system has the characteristics of dissipative structure. The process of the formation for the sustainable growth capability is one of self-organization operations. The evolution and development of sustainable growth capability is the result of inter-functions and inter-operations among all the sub-systems. On the whole, the current level of sustainable growth capability, the four-capability structure and the random rise-and-fall elements of the external environment determine the direction, speed and level of transition of sustainable growth capability. The self-organization mechanism of the enterprise＇s sustainable growth can be illustrated by the instability of system evolution, the sequence parameter, the potential function and the nonequilibrium phase transition. Chinese firms must pay attention to industry selecting and positioning, technology innovation, institution reform and cultivation of market power, and accelerate the formation of self-organization and effective operation through the dynamic integration and inter-operation of industry, technology, institution and market power. Only in this way can firms cultivate and develop their sustainable growth capability and realize enterprises＇ sustainable growth finally.

ANALYSIS OF THE GROWTH MECHANISM OF TiAl_3 WHISKERS PREPARED BY IN SITU REACTION IN MOLTEN ALUMINUM

Some TiAl3 whiskers are found to be produced simultaneously during the formation process of TiB2 Particulates fabricated by in situ reaction in molten aluminum. The thec t of temperature of molten aluminum on the morphologies of the TiAl3 whiskers and the growth mechanism of the whiskers are studied in this paper. The results show that the aspect rutio of the TiAl3 whiskers decreases with the increase of the temperoture. The growth of the whiskers is proved to be controlled by a Vapor-LiquidSoltd (VLS) mechanism. The titanium and aluminum atoms in the catalytic droplet,however, have been coofrmed to react with each othen which is dtherent from other whlskcrs growing by a VLS mcchanism where the compostion in the catalytic droplet is a constant.

Controllable synthesis,characterization,and growth mechanism of hollow Zn_x Cd_(1-x) S spheres generated by a one-step thermal evaporation method

Novel hollow ZnxCdl xS spheres that are uniform in size are synthesized through the one-step thermal evaporation of a mixture of Zn and CdS powder. From an X-ray diffraction （XRD） study, the hexagonal wurtzite phase of ZnxCdl_xS is verified, and the Zn mole fraction （x） is determined to be 0.09. According to the experimental results, we propose a mechanism for the growth of Zn0.09Cd0.91S hollow spheres. The results of the cathodoluminescence investigation indicate uniform Zn, Cd, and S distribution of alloyed Zn0.09Cd0.91S, instead of separate CdS, ZnS, or nanocrystals of a core- shell structure. To the best of our knowledge, the fabrication of ZnxCd1-xS hollow spheres of this kind by one-step thermal evaporation has never been reported. This work would present a new method of growing and applying hollow spheres on Si substrates, and the discovery of the Zn0.09Cd0.91S hollow spheres would make the investigation of ZnxCd1-xS micro/nanostructures more interesting and intriguing.

Preparation,Growth Mechanisms and Characterizations of ZnSe Films via the Solvothermal Method

With diethylamine as a solvent, ZnSe films were formed on the Si substrate directly from zinc and selenium through the modified solvothermal method. The effects of holding temperature, deposition time and substrate surface treatment on the quality and morphologies of the ZnSe films were investigated. The growth mechanism of ZnSe films was proved to be a layer-nucleation growth process, which was tied in with the Stranski-Krastanov （SK） model. ZnSe films were identified by the X-ray diffraction pattern （XRD）, the scanning electron microscope （SEM）, the X-ray photoelectron spectroscope （XPS） and the photoluminescence （PL） techniques. The results indicate that the modified solvothermal method with diethylamine as a solvent is suitable to prepare high quality ZnSe films.

Shape controlled synthesis and growth mechanism of one-dimensional zinc oxide nanomaterials

Some types of ZnO nanostructures with various shape and size, including tetrapod-like ZnO (T-ZnO) nanorods, nanowires and nanonbbons, have been obtained by controlled growth process. The nanostructures of ZnO have been investigated by means of field-emission scanning electron microscope, transmission electron microscopy and high-resolution transmission electron microscopy. The growth mechanisms of various ZnO nanostructures were proposed and discussed.

THE GROWTH MECHANISM OF Al_2O_3/Al COMPOS-ITES BY DIRECTED OXIDATION OF MOLTEN METALS

The process of the directed oxidiation of alloy Al-1%Mg-7%Si was invertigated by X-Ray diffraction (XRD). optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectrometer(EDS) ,which included evolution of the surface of the melt in the incubation period, nucleation of Al2O3/metal composite and microstruc-ture of Lanxide material its growth front . Some new results about the mechanism of the for mation of Al2O3 are involved.

The influence of ablation products on the ablation resistance of C/C-SiC composites and the growth mechanism of SiO_2 nanowires

Ablation under oxyacetylene torch with heat flux of 4186.8（10%kW/m2 for 20 s was performed to evaluate the ablation resistance of C/C-SiC composites fabricated by chemical vapor infiltration（CVI） combined with liquid silicon infiltration（LSI） process.The results indicated that C/C-SiC composites present a better ablation resistance than C/C composites without doped SiC.The doped SiC and the ablation products SiO2 derived from it play key roles in ablation process.Bulk quantities of SiO2 nanowires with diameter of 80 nm-150 nm and length of tens microns were observed on the surface of specimens after ablation.The growth mechanism of the SiO_2 nanowires was interpreted with a developed vapor-liquid-solid（VLS） driven by the temperature gradient.

Wrinkling and Growth Mechanism of CuO Nanowires in Thermal Oxidation of Copper Foil

We report a systematic study on wrinkling and CuO nanowires （NWs） growth in the thermal oxidation of copper foil. Copper foils with thickness of 0.5 mm were thermally oxidized in air at 500℃ for 0.5-10 h. It is found that all the samples have wrinkles and the size of the wrinkles increases with the oxidation time increasing. CuO NWs can grow on both the sidehill and hilltop of wrinkle. The CuO NWs on sidehill are longer and denser than those on hilltop. The growth direction of the CuO NWs on sidehill is not vertical to the substrate but vertical to their growth surfaces. The process of wrinkling and CuO NWs growth can be divided into three stages： undulating, voiding, and cracking. The CuO NWs on both sidehill and hilltop grow at the undulating stage. However, only the CuO NWs on sidehill grow and those on hilltop stop growing at the voiding and cracking stages because of the void in hilltop. The local electric field in a wrinkle at undulating stage was calculated, and it is found that the difference of local electric field strengths between hilltop and sidehill is small, which indicates that the predominant driving force for the diffusion of Cu ion during CuO NWs growth is internal stress.

The Evolution of the Extinction and Growth Mechanism of the Silver Nanoplates

The time-dependence evolution of the extinction spectra of the silver nanoplates is studied to analyze the underlying physical mechanism of the growth process. As the synthesis cycles increase, the wavelength of the absorption peak is first blue-shifted and then is followed by the red shift, attributing to the mode alteration of the longitudinal surface plasmon resonance of the silver nanoplates. The capping agents are also optimized for the convenient and speedy growth of the large integrated Ag nanostructure. These observations expand the comprehensive understanding of plasmon resonance of the Ag nanoplates, and give a better manipulation of their applications in the plasmonie nanodevices.

Solvent Synthesis,Growth Mechanism and Photocatalytic Properties of AgInS_2 Nanoplate and Nanoparticle

Orthorhombic AgInS2 nanoplate and nanoparticle were synthesized using pyridine and 1-dodecanethiol as the solvent.The obtained products were characterized by X-ray diffraction（XRD）,field-emission scanning electron microscope（FESEM）,field-emission transmission electron microscope（FETEM）,and the possible growth mechanism of AgInS2 was also proposed by the exploration of reaction temperature and time.Meanwhile,the bandgap of AgInS2 was calculated by the UV-Vis diffuse reflectance spectrum,and the photocatalytic activity was also investigated.Those experimental results indicate that the reaction temperature,reaction time and solvent have an influence on phase and morphology of AgInS2,and both AgInS2 nanoplate and nanoparticle have some ability on photocatalytic degradation of organic dyes under UV-Vis light irradiation.