The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the cent...The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the central determinant of the functional properties of neurons and neural circuits.The topological and structural morphology of axons and dendrites defines and determines how synapses are conformed.The morphological diversity of axon and dendrite arborization governs the neuron’s inputs,synaptic integration,neuronal computation,signal transmission,and network circuitry,hence defining the particular connectivity and function of the different brain areas.展开更多
Zn-I_(2) batteries have emerged as promising next-generation energy storage systems owing to their inherent safety,environmental compatibility,rapid reaction kinetics,and small voltage hysteresis.Nevertheless,two crit...Zn-I_(2) batteries have emerged as promising next-generation energy storage systems owing to their inherent safety,environmental compatibility,rapid reaction kinetics,and small voltage hysteresis.Nevertheless,two critical challenges,i.e.,zinc dendrite growth and polyiodide shuttle effect,severely impede their commercial viability.To conquer these limitations,this study develops a multifunctional separator fabricated from straw-derived carboxylated nanocellulose,with its negative charge density further reinforced by anionic polyacrylamide incorporation.This modification simultaneously improves the separator’s mechanical properties,ionic conductivity,and Zn^(2+)ion transfer number.Remarkably,despite its ultrathin 20μm profile,the engineered separator demonstrates exceptional dendrite suppression and parasitic reaction inhibition,enabling Zn//Zn symmetric cells to achieve impressive cycle life(>1800 h at 2 m A cm^(-2)/2 m Ah cm^(-2))while maintaining robust performance even at ultrahigh areal capacities(25 m Ah cm^(-2)).Additionally,the separator’s anionic characteristic effectively blocks polyiodide migration through electrostatic repulsion,yielding Zn-I_(2) batteries with outstanding rate capability(120.7 m Ah g^(-1)at 5 A g^(-1))and excellent cyclability(94.2%capacity retention after 10,000 cycles).And superior cycling stability can still be achieved under zinc-deficient condition and pouch cell configuration.This work establishes a new paradigm for designing high-performance zinc-based energy storage systems through rational separator engineering.展开更多
Osteogenesis imperfecta(OI)is a group of diseases caused by defects in type I collagen processing which result in skeletal fragility.While these disorders have been regarded as defects in osteoblast function,the role ...Osteogenesis imperfecta(OI)is a group of diseases caused by defects in type I collagen processing which result in skeletal fragility.While these disorders have been regarded as defects in osteoblast function,the role of matrix-embedded osteocytes in OI pathogenesis remains largely unknown.Homozygous human SP7(c.946 C>T,R316C)mutation results in a recessive form of OI characterized by fragility fractures,low bone mineral density and osteocyte dendrite defects.To better understand how the OI-causing R316C mutation affects the function of SP7,we generated Sp7^(R342C)knock-in mice.Consistent with patient phenotypes,Sp7^(R342C/R342C)mice demonstrate increased cortical porosity and reduced cortical bone mineral density.Sp7^(R342C/R342C)mice show osteocyte dendrite defects,increased osteocyte apoptosis,and intracortical bone remodeling with ectopic intracortical osteoclasts and elevated osteocyte Tnfsf11 expression.展开更多
Li metal is widely recognized as the desired anode for next-generation energy storage,Li metal batteries,due to its highest theoretical capacity and lowest potential.Nonetheless,it suffers from unstable electrochemica...Li metal is widely recognized as the desired anode for next-generation energy storage,Li metal batteries,due to its highest theoretical capacity and lowest potential.Nonetheless,it suffers from unstable electrochemical behaviors like dendrite growth and side reactions in practical application.Herein,we report a highly stable anode with collector,Li_(5)Mg@Cu,realized by the melting-rolling process.The Li_(5)Mg@Cu anode delivers ultrahigh cycle stability for 2000 and 1000 h at the current densities of 1 and 2 mA cm^(-2),respectively in symmetric cells.Meanwhile,the Li_(5)Mg@Cu|LFP cell exhibits a high-capacity retention of 91.8% for 1000 cycles and 78.8% for 2000 cycles at 1 C.Moreover,we investigate the suppression effects of Mg on the dendrite growth by studying the performance of Li_(x)Mg@Cu electrodes with different Mg contents(2.0-16.7 at%).The exchange current density,surface energy,Li^(+)diffusion coefficient,and chemical stability of Li_(x)Mg@Cu concretely reveal this improving suppression effect when Mg content becomes higher.In addition,a Mg-rich phase with“hollow brick”morphology forming in the high Mg content Li_(x)Mg@Cu guides the uniform deposition of Li.This study reveals the suppression effects of Mg on Li dendrites growth and offers a perspective for finding the optimal component of Li-Mg alloys.展开更多
Secondary dendrite orientation and wall thickness considerably affect the stress rupture life of thin-walled samples.However,the effect of the secondary dendrite orientation on the thickness debit effect of nickel-bas...Secondary dendrite orientation and wall thickness considerably affect the stress rupture life of thin-walled samples.However,the effect of the secondary dendrite orientation on the thickness debit effect of nickel-based single-crystal superalloys has not been thoroughly investigated until now.Owing to geometrical constraints,typical sheet samples cannot reveal the mechanism responsible for the thickness debit effect in turbine blades.This study examined the effect of secondary dendrite orientation on the thickness debit effect of nickel-based single-crystal superalloys at 1100℃/137 MPa in tubular samples.As the wall thickness decreased from 1.5 mm to 0.3 mm,the stress rupture life decreased from approximately 170 h to 64 h,demonstrating a noticeable thickness debit effect.Among the different secondary dendrite orientation areas,the variation in plastic deformation difference increased from 7%(1.5 mm)to 45%(0.5 mm)and subsequently decreased to 4%(0.3 mm).In thinner samples,the thickness contraction and microstructure evolution were more pronounced in the[100]areas than that in the[110]and[210]areas.The theoretical calculation quantitatively indicated that for the effective stress increased,the contribution of plastic deformation(45%)was slightly lower than that of oxidation(55%)in 0.3 mm samples;nevertheless,plastic deformation played a prominent role in 0.5,0.8,1,and 1.5 mm samples and increased from 61%(0.5 mm samples)to 85%(1.5 mm samples).In thinner samples,the larger plastic deformation in the secondary dendrite orientation of the[100]areas and oxidation increased the effective stress,resulting in a shorter rupture life.These findings are conducive to the structural optimization and performance improvement of turbine blades.展开更多
All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation ...All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation within solid-state electrolytes(SSEs)remain inadequately understood.To address this knowledge gap,we propose an electrochemical-mechanical coupled phase-field model designed to simulate the complex processes of lithium deposition and crack propagation in SSEs.This framework systematically examines the influence of initial defect characteristics—including morphology,dimensions,and fracture toughness—on dendrite penetration dynamics.Furthermore,it identifies potential initiation pathways for detrimental lithium deposition within the electrolyte bulk.The model also quantifies the critical role of electrolyte elastic modulus and grain boundary orientation in modulating deposition behavior.Notably,simulation results demonstrate concordance with existing experimental observations,thereby establishing a fundamental theoretical framework for understanding failure mechanisms.This work provides crucial mechanistic insights and predictive capabilities to guide the rational design of failure-resistant SSEs for all-solid-state lithium metal batteries.展开更多
The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithiu...The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator.The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition stage.Most importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance(145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite.The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm^(-2)with a polarization voltage of only 29.3 mV.Additionally,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity attenuation.The improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.展开更多
The widespread application of solid-state polymer electrolytes(SPEs)is impeded due to their limited ionic conductivity,narrow electrochemical window and lithium dendrite problem.In this work,Mg-metal-organic framework...The widespread application of solid-state polymer electrolytes(SPEs)is impeded due to their limited ionic conductivity,narrow electrochemical window and lithium dendrite problem.In this work,Mg-metal-organic frameworks(MOF)is incorporated into a polyethylene oxide(PEO)-based polymer solid electrolyte,leading to the insitu formation of LiF and other compounds at the electrolyte interface.This modification significantly improves lithium-ion transport capabilities and regulates lithium deposition behavior,suppressing the formation of lithium dendrites.展开更多
Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in re...Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in rechargeable Li metal batteries(LMBs)is hindered due to the short cycle life caused by uncontrolled dendrite growth.In this work,a dendrite-free anode(Li–Sn/Cu)is reinforced synergistically by lithophilic alloy,and a 3D grid structure is designed.Li^(+)diffusion and uniform nucleation are effectively induced by the lithophilic alloy Li_(22)Sn_(5).Moreover,homogeneous deposition of Li^(+)is caused by the reversible gridded Li plating/stripping effect of Cu mesh.Furthermore,the local space electric field is redistributed throughout the 3D conductive network,whereby the tip effect is suppressed,thus inhibiting the growth of Li dendrites.Also,the volume expansion of the anode during cycling is eased by the 3D grid structure.The results show that the Li–Sn/Cu symmetric battery can stably cycle for more than 10,000 h at 2 mA.cm^(-2)and 1 mAh.cm^(-2)with a low overpotential.The capacity retention of the LiFePO_(4)full battery remains above 90.7%after 1,000 cycles at 1C.This work provides a facile,low-cost,and effective strategy for obtaining Li metal batteries with ultra-long cycle life.展开更多
Dendrite growth represents one of the most significant challenges that impede the development of aqueous zinc-ion batteries.Herein,Gd^(3+)ions are introduced into conventional electrolytes as a microlevelling agent to...Dendrite growth represents one of the most significant challenges that impede the development of aqueous zinc-ion batteries.Herein,Gd^(3+)ions are introduced into conventional electrolytes as a microlevelling agent to achieve dendrite-free zinc electrodeposition.Simulation and experimental results demonstrate that these Gd^(3+)ions are preferentially adsorbed onto the zinc surface,which enables dendritefree zinc anodes by activating the microlevelling effect during electrodeposition.In addition,the Gd^(3+)additives effectively inhibit side reactions and facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+),leading to highly reversible zinc plating/stripping.Due to these improvements,the zinc anode demonstrates a significantly prolonged cycle life of 2100 h and achieves an exceptional average Coulombic efficiency of 99.72%over 1400 cycles.More importantly,the Zn//NH_(4)V_(4)O_(10)full cell shows a high capacity retention rate of 85.6%after 1000 cycles.This work not only broadens the application of metallic cations in battery electrolytes but also provides fundamental insights into their working mechanisms.展开更多
Lithium metal has emerged as a highly promising anode material for enhancing the energy density of secondary batteries,attributed to its high theoretical specific capacity and low electrochemical potential.However,saf...Lithium metal has emerged as a highly promising anode material for enhancing the energy density of secondary batteries,attributed to its high theoretical specific capacity and low electrochemical potential.However,safety concerns related to lithium dendrite-induced short circuits and suboptimal electrochemical performance have impeded the commercial viability of lithium metal batteries.Current research efforts primarily focus on altering the solvated structure of Li+by modifying the current collector or introducing electrolyte additives to lower the nucleation barrier,expedite the desolvation process,and suppress the growth of lithium dendrites.Nevertheless,an integrated approach that combines the advantages of these two strategies remains elusive.In this study,we successfully employed metal-organic salt additives with lithophilic properties to accelerate the desolvation process,reduce the nucleation barrier of Li+,and modulate its solvated structure.This approach enhanced the inorganic compound content in the solid electrolyte interphase(SEI)on lithium foil surfaces,leading to stable Li+deposition and stripping.Specifically,Li||Cu cells demonstrated excellent cycle life and Coulombic efficiency(97.28%and 98.59%,respectively)at 0.5 m A/cm^(2)@0.5 m Ah/cm^(2)and 1 m A/cm^(2)@1 m Ah/cm^(2)for 410 and 240 cycles,respectively.Li||Li symmetrical cells showed no short circuit at 1 m A/cm^(2)@1 m Ah/cm^(2)for 1150 h,and Li||LFP full cells retained 68.9%of their capacity(104.6 m Ah/g)after 250 cycles at N/P(1.1:1.0)with a current density of 1C.展开更多
The ineluctable introduction of lithium salt to polymer solid-state electrolytes incurs a compromise between strength,ionic conductivity,and thickness.Here,we propose Al_(2)O_(3)-coated polyimide(AO/PI)porous film as ...The ineluctable introduction of lithium salt to polymer solid-state electrolytes incurs a compromise between strength,ionic conductivity,and thickness.Here,we propose Al_(2)O_(3)-coated polyimide(AO/PI)porous film as a high-strength substrate to support fast-ion-conducting polymer-in-salt(PIS)solid-state electrolytes,aiming to suppress lithium dendrite growth and improve full-cell performance.The Al_(2)O_(3)coating layer not only refines the wettability of polyimide porous film to PIS,but also performs as a high modulus protective layer to suppress the growth of lithium dendrites.The resulting PI/AO@PIS exhibits a small thickness of only 35μm with an outstanding tensile strength of 11.3 MPa and Young's modulus of 537.6 MPa.In addition,the PI/AO@PIS delivers a high ionic conductivity of 0.1 m S/cm at 25°C.As a result,the PI/AO@PIS enables symmetric Li cells to achieve exceptional cyclability for over 1000 h at 0.1 m A/cm2without noticeable lithium dendrite formation.Moreover,the PI/AO@PIS-based LiFePO4||Li full cells demonstrate outstanding rate performance(125.7 m Ah/g at 5 C)and impressive cycling stability(96.1%capacity retention at 1 C after 200 cycles).This work highlights the efficacy of enhancing the mechanical properties of polymer matrices and extending cell performance through the incorporation of a dense inorganic interface layer.展开更多
A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrit...A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.展开更多
Regulating the crystal texture of zinc deposition is a promising approach to suppress dendrite formation and improve the reversibility of zinc anodes in aqueous zinc-ion batteries.While previous research has mainly fo...Regulating the crystal texture of zinc deposition is a promising approach to suppress dendrite formation and improve the reversibility of zinc anodes in aqueous zinc-ion batteries.While previous research has mainly focused on developing the Zn(002)texture,investigations into other crystal planes remain scarce.However,exploring alternative crystal planes is crucial for advancing zinc anode performance,as different planes may offer unique advantages in terms of stability and reversibility.Herein,we introduce N-acetylcysteamine(NAC)as an electrolyte additive.It revealed that NAC induces an unexpected exfoliation of the electrodeposited zinc layer,which exhibits preferred orientations along the(102)and(103)planes.Inspired by this anomalous deposition phenomenon,we achieved unconventional Zn(102)and Zn(103)oriented deposition.We demonstrate that NAC molecules adsorb on the Zn surface via thiol groups,modulating the surface energy of different planes to promote the exposure of the two textures.Further characterization,including electrochemical quartz crystal microbalance,electric double-layer capacitance,and contact angle tests,confirms that NAC forms a hydrophobic selfassembled layer,effectively suppressing side reactions.Benefiting from this multifunctional additive,the zinc anode exhibited a long lifespan of 1150 and 780 h under 1 mA cm^(-2)/1 mAh cm^(-2)and 5 mA cm^(-2)/5 mAh cm^(-2),respectively.Moreover,the assembled Zn||V_(2)O_(5)H_(2)O full cells demonstrated prominent electrochemical reversibility.This work not only achieves unconventional Zn(102)and Zn(103)oriented deposition but also provides a novel strategy for designing high-performance zinc-ion batteries.展开更多
Lithium-sulfur batteries(LSBs)are considered as the most promising energy storage technologies owing to their large theoretical energy density(2500Wh/kg)and specific capacity(1675 mAh/g).However,the heavy shuttle effe...Lithium-sulfur batteries(LSBs)are considered as the most promising energy storage technologies owing to their large theoretical energy density(2500Wh/kg)and specific capacity(1675 mAh/g).However,the heavy shuttle effect of polysulfides and the growth of lithium dendrites greatly hinder their further development and commercial application.In this paper,cobalt-molybdenum bimetallic carbides heterostructure(Co_(6)Mo_(6)C_(2)@Co@NC)was successfully prepared through chemical etching procedure of ZIF-67 precursor with sodium molybdate and the subsequent high temperature annealing process.The obtained dodecahedral Co_(6)Mo_(6)C_(2)@Co@NC with hollow and porous structure provides large specific surface area and plentiful active sites,which speeds up the chemisorption and catalytic conversion of polysulfides,thus mitigating the shuttle effect of polysulfides and the generation of lithium dendrites.When applied as the LSBs separator modifier layer,the cell with modified separator present excellent rate capability and durable cycling stability.In particular,the cell with Co_(6)Mo_(6)C_(2)@Co@NC/PP separator can maintain the high capacity of 738 mAh/g at the current density of 2 C and the specific capacity of 782.6 mAh/g after 300 cycles at 0.5 C,with the coulombic efficiency(CE)near to 100%.Moreover,the Co_(6)Mo_(6)C_(2)@Co@NC/PP battery exhibits the impressive capacity of 431 mAh/g in high sulfur loading(4.096 mg/cm^(2))at 0.5 C after 200 cycles.This work paves the way for the development of bimetallic carbides heterostructure multifunctional catalysts for durable Li-S battery applications and reveals the synergistic regulation of polysulfides and lithium dendrites through the optimization of the structure and composition.展开更多
Zinc(Zn)-air batteries are widely used in secondary battery research owing to their high theoretical energy density,good electrochemical reversibility,stable discharge performance,and low cost of the anode active mate...Zinc(Zn)-air batteries are widely used in secondary battery research owing to their high theoretical energy density,good electrochemical reversibility,stable discharge performance,and low cost of the anode active material Zn.However,the Zn anode also leads to many challenges,including dendrite growth,deformation,and hydrogen precipitation self-corrosion.In this context,Zn dendrite growth has a greater impact on the cycle lives.In this dissertation,a dendrite growth model for a Zn-air battery was established based on electrochemical phase field theory,and the effects of the charging time,anisotropy strength,and electrolyte temperature on the morphology and growth height of Zn dendrites were studied.A series of experiments was designed with different gradient influencing factors in subsequent experiments to verify the theoretical simulations,including elevated electrolyte temperatures,flowing electrolytes,and pulsed charging.The simulation results show that the growth of Zn dendrites is controlled mainly by diffusion and mass transfer processes,whereas the electrolyte temperature,flow rate,and interfacial energy anisotropy intensity are the main factors.The experimental results show that an optimal electrolyte temperature of 343.15 K,an optimal electrolyte flow rate of 40 ml·min^(-1),and an effective pulse charging mode.展开更多
The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of den...The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of dendritic solidification structures.Combining scanning electron microscopy and energy-dispersive scanning analysis and ANSYS simulation,the high-precision image processing software Mimics Research was utilized to conduct the extraction of dendritic morphologies.Reverse engineering software NX Imageware was employed for the 3D reconstruction of two-dimensional dendritic morphologies,restoring the dendritic characteristics in three-dimensional space.The results demonstrate that in a two-dimensional plane,dendrites connect with each other to form irregularly shaped“ring-like”structures.These dendrites have a thickness greater than 0.1 mm along the Z-axis direction,leading to the envelopment of molten steel by dendrites in a 3D space of at least 0.1 mm.This results in obstructed flow,confirming the“bridging”of dendrites in three-dimensional space,resulting in a tendency for central segregation.Dense and dispersed tiny dendrites,under the influence of heat flow direction,interconnect and continuously grow,gradually forming primary and secondary dendrites in three-dimensional space.After the completion of dendritic solidification and growth,these microdendrites appear dense and dispersed on the two-dimensional plane,providing the nuclei for the formation of new dendrites.When reduction occurs at a solid fraction of 0.46,there is a noticeable decrease in dendritic spacing,resulting in improved central segregation.展开更多
Effect of direct current electric field （DCEF） on corrosion behaviour of copper printed circuit board （PCB-Cu）, Cl-ion migration behaviour, dendrites growth under thin electrolyte layer was investigated using pote...Effect of direct current electric field （DCEF） on corrosion behaviour of copper printed circuit board （PCB-Cu）, Cl-ion migration behaviour, dendrites growth under thin electrolyte layer was investigated using potentiodynamic polarization and scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS）. Results indicate that DCEF decreases the corrosion of PCB-Cu;Cl-ions directionally migrate from the negative pole to the positive pole, and enrich on the surface of the positive pole, which causes serious localized corrosion; dendrites grow on the surface of the negative pole, and the rate and scale of dendrite growth become faster and greater with the increase of external voltage and exposure time, respectively.展开更多
Nucleation of dendritic primaryα（Al） phase with addition of element Ce and Sr in hypoeutectic Al-7%Si-Mg cast alloy was investigated by using differential scanning calorimetry （DSC） and scanning electron microsco...Nucleation of dendritic primaryα（Al） phase with addition of element Ce and Sr in hypoeutectic Al-7%Si-Mg cast alloy was investigated by using differential scanning calorimetry （DSC） and scanning electron microscopy. DSC results were used to calculate the activation energy and nucleation work of primaryα（Al） phase. The results show that the values of activation energy and nucleation work are decreased and the nucleation frequency is increased with the additions of Ce and Sr to the alloys. Moreover, the grain size of dendriticα（Al） phase is well refined, and the nucleation temperatures of primaryα（Al） dendrites are decreased with the additions of Ce and Sr. The effects of elements Ce and Sr additions on kinetic nucleation of primary α（Al） phases were also discussed in hypoeutectic Al-7%Si-Mg cast alloy.展开更多
Primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with diffe...Primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with different diameters.The experimental results show the measured PDAS increases with increasing diameter of the sample.At the growth velocity of 5 μm/s,its value changes from 161.5 μm for the sample with 1.8 mm in diameter to 240.4 μm for the sample with 7 mm in diameter.The strong melt convection in large diameter samples causes a high bulk alloy composition and a high concentration gradient in peritectic β phase,resulting in a larger PDAS.Simultaneously,the high concentration gradient could effectively promote the peritectic transformation,enhancing the dissolution of the thin α dendrite.展开更多
基金supported by the Wellcome Trust(grant No.103852).
文摘The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the central determinant of the functional properties of neurons and neural circuits.The topological and structural morphology of axons and dendrites defines and determines how synapses are conformed.The morphological diversity of axon and dendrite arborization governs the neuron’s inputs,synaptic integration,neuronal computation,signal transmission,and network circuitry,hence defining the particular connectivity and function of the different brain areas.
基金the financial support from the Natural Science Foundation of Jiangsu Province(BK20231292)the Jiangsu Agricultural Science and Technology Innovation Fund(CX(24)3091)+6 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX25_1429)the National Key R&D Program of China(2024YFE0109200)the Fundamental Research Funds for the Central Universities(No.2024300440)Guangdong Basic and Applied Basic Research Foundation(2025A1515011098)the National Natural Science Foundation of China(12464032)the Natural Science Foundation of Jiangxi Province(20232BAB201032)Ji'an Science and Technology Plan Project(2024H-100301)。
文摘Zn-I_(2) batteries have emerged as promising next-generation energy storage systems owing to their inherent safety,environmental compatibility,rapid reaction kinetics,and small voltage hysteresis.Nevertheless,two critical challenges,i.e.,zinc dendrite growth and polyiodide shuttle effect,severely impede their commercial viability.To conquer these limitations,this study develops a multifunctional separator fabricated from straw-derived carboxylated nanocellulose,with its negative charge density further reinforced by anionic polyacrylamide incorporation.This modification simultaneously improves the separator’s mechanical properties,ionic conductivity,and Zn^(2+)ion transfer number.Remarkably,despite its ultrathin 20μm profile,the engineered separator demonstrates exceptional dendrite suppression and parasitic reaction inhibition,enabling Zn//Zn symmetric cells to achieve impressive cycle life(>1800 h at 2 m A cm^(-2)/2 m Ah cm^(-2))while maintaining robust performance even at ultrahigh areal capacities(25 m Ah cm^(-2)).Additionally,the separator’s anionic characteristic effectively blocks polyiodide migration through electrostatic repulsion,yielding Zn-I_(2) batteries with outstanding rate capability(120.7 m Ah g^(-1)at 5 A g^(-1))and excellent cyclability(94.2%capacity retention after 10,000 cycles).And superior cycling stability can still be achieved under zinc-deficient condition and pouch cell configuration.This work establishes a new paradigm for designing high-performance zinc-based energy storage systems through rational separator engineering.
基金support from the National Institute of Health(K99AR081897,R00AR081897)M.N.W.acknowledges funding support from the National Institute of Health(P01DK011794,R01DK116716)+1 种基金the Smith Family Foundation Odyssey Award,and the Chen Institute Massachusetts General Hospital Research Scholar(2024-2029)awardμCT and bone histomorphometry were performed by the Center for Skeletal Research at Massachusetts General Hospital,a NIH-funded program(P30AR066261 and AR075042)led by Mary Bouxsein and Marie Demay.
文摘Osteogenesis imperfecta(OI)is a group of diseases caused by defects in type I collagen processing which result in skeletal fragility.While these disorders have been regarded as defects in osteoblast function,the role of matrix-embedded osteocytes in OI pathogenesis remains largely unknown.Homozygous human SP7(c.946 C>T,R316C)mutation results in a recessive form of OI characterized by fragility fractures,low bone mineral density and osteocyte dendrite defects.To better understand how the OI-causing R316C mutation affects the function of SP7,we generated Sp7^(R342C)knock-in mice.Consistent with patient phenotypes,Sp7^(R342C/R342C)mice demonstrate increased cortical porosity and reduced cortical bone mineral density.Sp7^(R342C/R342C)mice show osteocyte dendrite defects,increased osteocyte apoptosis,and intracortical bone remodeling with ectopic intracortical osteoclasts and elevated osteocyte Tnfsf11 expression.
基金supported by the Qingdao Jiuhuanxinyue New Energy Technology Co.,Ltd.the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515120071)+2 种基金the 21C Innovation Laboratory,Contemporary Amperex Technology Ltd.(Grant No.21C-OP-202112)the financial support from the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515011873)the Shenzhen Science and Technology Program(Grant No.JCYJ20220531095212027).
文摘Li metal is widely recognized as the desired anode for next-generation energy storage,Li metal batteries,due to its highest theoretical capacity and lowest potential.Nonetheless,it suffers from unstable electrochemical behaviors like dendrite growth and side reactions in practical application.Herein,we report a highly stable anode with collector,Li_(5)Mg@Cu,realized by the melting-rolling process.The Li_(5)Mg@Cu anode delivers ultrahigh cycle stability for 2000 and 1000 h at the current densities of 1 and 2 mA cm^(-2),respectively in symmetric cells.Meanwhile,the Li_(5)Mg@Cu|LFP cell exhibits a high-capacity retention of 91.8% for 1000 cycles and 78.8% for 2000 cycles at 1 C.Moreover,we investigate the suppression effects of Mg on the dendrite growth by studying the performance of Li_(x)Mg@Cu electrodes with different Mg contents(2.0-16.7 at%).The exchange current density,surface energy,Li^(+)diffusion coefficient,and chemical stability of Li_(x)Mg@Cu concretely reveal this improving suppression effect when Mg content becomes higher.In addition,a Mg-rich phase with“hollow brick”morphology forming in the high Mg content Li_(x)Mg@Cu guides the uniform deposition of Li.This study reveals the suppression effects of Mg on Li dendrites growth and offers a perspective for finding the optimal component of Li-Mg alloys.
基金financially supported by the Science Center for Gas Turbine Project(No.P2021-AB-Ⅳ-001-002).
文摘Secondary dendrite orientation and wall thickness considerably affect the stress rupture life of thin-walled samples.However,the effect of the secondary dendrite orientation on the thickness debit effect of nickel-based single-crystal superalloys has not been thoroughly investigated until now.Owing to geometrical constraints,typical sheet samples cannot reveal the mechanism responsible for the thickness debit effect in turbine blades.This study examined the effect of secondary dendrite orientation on the thickness debit effect of nickel-based single-crystal superalloys at 1100℃/137 MPa in tubular samples.As the wall thickness decreased from 1.5 mm to 0.3 mm,the stress rupture life decreased from approximately 170 h to 64 h,demonstrating a noticeable thickness debit effect.Among the different secondary dendrite orientation areas,the variation in plastic deformation difference increased from 7%(1.5 mm)to 45%(0.5 mm)and subsequently decreased to 4%(0.3 mm).In thinner samples,the thickness contraction and microstructure evolution were more pronounced in the[100]areas than that in the[110]and[210]areas.The theoretical calculation quantitatively indicated that for the effective stress increased,the contribution of plastic deformation(45%)was slightly lower than that of oxidation(55%)in 0.3 mm samples;nevertheless,plastic deformation played a prominent role in 0.5,0.8,1,and 1.5 mm samples and increased from 61%(0.5 mm samples)to 85%(1.5 mm samples).In thinner samples,the larger plastic deformation in the secondary dendrite orientation of the[100]areas and oxidation increased the effective stress,resulting in a shorter rupture life.These findings are conducive to the structural optimization and performance improvement of turbine blades.
基金supported by the National Natural Science Foundation of China(No.52476053,No.22409209)Beijing Natural Science Foundation(No.3242017)。
文摘All-solid-state lithium metal batteries represent leading candidates for the next generation of highenergy-density rechargeable batteries.However,the coupled mechanisms governing dendrite growth and crack propagation within solid-state electrolytes(SSEs)remain inadequately understood.To address this knowledge gap,we propose an electrochemical-mechanical coupled phase-field model designed to simulate the complex processes of lithium deposition and crack propagation in SSEs.This framework systematically examines the influence of initial defect characteristics—including morphology,dimensions,and fracture toughness—on dendrite penetration dynamics.Furthermore,it identifies potential initiation pathways for detrimental lithium deposition within the electrolyte bulk.The model also quantifies the critical role of electrolyte elastic modulus and grain boundary orientation in modulating deposition behavior.Notably,simulation results demonstrate concordance with existing experimental observations,thereby establishing a fundamental theoretical framework for understanding failure mechanisms.This work provides crucial mechanistic insights and predictive capabilities to guide the rational design of failure-resistant SSEs for all-solid-state lithium metal batteries.
基金National Natural Science Foundation of China (Grant 52372083, 52173255)Opening Project of the Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials (JSKC24025)+1 种基金Special Funds for the Trans-formation of Scientific and Technological Achievements in Jiangsu Province(BA2023003)Collaborative Innovation Center for Advanced Micro/nanomaterials and Equipment (Co-constructed by Jiangsu Province and Ministry of Education)。
文摘The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator.The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition stage.Most importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance(145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite.The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm^(-2)with a polarization voltage of only 29.3 mV.Additionally,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity attenuation.The improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.
基金supported by the National Natural Science Foundation of China(Nos.52374302 and 51874099)the Natural Science Foundation of Fujian Province’s Key Project(No.2021J02031)+1 种基金support from the open fund from Academy of Carbon Neutrality of Fujian Normal University(No.TZH_(2)022-06)We also thank the Undergraduate Training Programs for Innovation and Entrepreneurship(No.cxx1-2024363)。
文摘The widespread application of solid-state polymer electrolytes(SPEs)is impeded due to their limited ionic conductivity,narrow electrochemical window and lithium dendrite problem.In this work,Mg-metal-organic frameworks(MOF)is incorporated into a polyethylene oxide(PEO)-based polymer solid electrolyte,leading to the insitu formation of LiF and other compounds at the electrolyte interface.This modification significantly improves lithium-ion transport capabilities and regulates lithium deposition behavior,suppressing the formation of lithium dendrites.
基金supported by the National Natural Science Foundation of China(No.52401221)Shandong Provincial Natural Science Foundation,China(No.ZR2022QE014)+1 种基金the Basic Scientific Research Fund for Central Universities(No.202112018)the Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)。
文摘Lithium(Li)metal is considered the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,the application of Li anode in rechargeable Li metal batteries(LMBs)is hindered due to the short cycle life caused by uncontrolled dendrite growth.In this work,a dendrite-free anode(Li–Sn/Cu)is reinforced synergistically by lithophilic alloy,and a 3D grid structure is designed.Li^(+)diffusion and uniform nucleation are effectively induced by the lithophilic alloy Li_(22)Sn_(5).Moreover,homogeneous deposition of Li^(+)is caused by the reversible gridded Li plating/stripping effect of Cu mesh.Furthermore,the local space electric field is redistributed throughout the 3D conductive network,whereby the tip effect is suppressed,thus inhibiting the growth of Li dendrites.Also,the volume expansion of the anode during cycling is eased by the 3D grid structure.The results show that the Li–Sn/Cu symmetric battery can stably cycle for more than 10,000 h at 2 mA.cm^(-2)and 1 mAh.cm^(-2)with a low overpotential.The capacity retention of the LiFePO_(4)full battery remains above 90.7%after 1,000 cycles at 1C.This work provides a facile,low-cost,and effective strategy for obtaining Li metal batteries with ultra-long cycle life.
基金supported by the Scientific Research and Technology Development Project of China National Petroleum Corporation(Grant Nos.2024ZG50,2022DQ03-03)the National Natural Science Foundation of China(Grant Nos.52372252)the Science and Technology Innovation Program of Hunan Province(Grant Nos.2024RC1022).
文摘Dendrite growth represents one of the most significant challenges that impede the development of aqueous zinc-ion batteries.Herein,Gd^(3+)ions are introduced into conventional electrolytes as a microlevelling agent to achieve dendrite-free zinc electrodeposition.Simulation and experimental results demonstrate that these Gd^(3+)ions are preferentially adsorbed onto the zinc surface,which enables dendritefree zinc anodes by activating the microlevelling effect during electrodeposition.In addition,the Gd^(3+)additives effectively inhibit side reactions and facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+),leading to highly reversible zinc plating/stripping.Due to these improvements,the zinc anode demonstrates a significantly prolonged cycle life of 2100 h and achieves an exceptional average Coulombic efficiency of 99.72%over 1400 cycles.More importantly,the Zn//NH_(4)V_(4)O_(10)full cell shows a high capacity retention rate of 85.6%after 1000 cycles.This work not only broadens the application of metallic cations in battery electrolytes but also provides fundamental insights into their working mechanisms.
基金supported by Yunnan Natural Science Foundation Project(No.202202AG050003)Yunnan Fundamental Research Projects(Nos.202101BE070001-018 and 202201AT070070)+1 种基金the National Youth Talent Support Program of Yunnan Province China(No.YNQR-QNRC-2020-011)Yunnan Engineering Research Center Innovation Ability Construction and Enhancement Projects(No.2023-XMDJ-00617107)。
文摘Lithium metal has emerged as a highly promising anode material for enhancing the energy density of secondary batteries,attributed to its high theoretical specific capacity and low electrochemical potential.However,safety concerns related to lithium dendrite-induced short circuits and suboptimal electrochemical performance have impeded the commercial viability of lithium metal batteries.Current research efforts primarily focus on altering the solvated structure of Li+by modifying the current collector or introducing electrolyte additives to lower the nucleation barrier,expedite the desolvation process,and suppress the growth of lithium dendrites.Nevertheless,an integrated approach that combines the advantages of these two strategies remains elusive.In this study,we successfully employed metal-organic salt additives with lithophilic properties to accelerate the desolvation process,reduce the nucleation barrier of Li+,and modulate its solvated structure.This approach enhanced the inorganic compound content in the solid electrolyte interphase(SEI)on lithium foil surfaces,leading to stable Li+deposition and stripping.Specifically,Li||Cu cells demonstrated excellent cycle life and Coulombic efficiency(97.28%and 98.59%,respectively)at 0.5 m A/cm^(2)@0.5 m Ah/cm^(2)and 1 m A/cm^(2)@1 m Ah/cm^(2)for 410 and 240 cycles,respectively.Li||Li symmetrical cells showed no short circuit at 1 m A/cm^(2)@1 m Ah/cm^(2)for 1150 h,and Li||LFP full cells retained 68.9%of their capacity(104.6 m Ah/g)after 250 cycles at N/P(1.1:1.0)with a current density of 1C.
基金the financial support from the 261Project of MIIT and Natural Science Foundation of Jiangsu Province(No.BK20240179)。
文摘The ineluctable introduction of lithium salt to polymer solid-state electrolytes incurs a compromise between strength,ionic conductivity,and thickness.Here,we propose Al_(2)O_(3)-coated polyimide(AO/PI)porous film as a high-strength substrate to support fast-ion-conducting polymer-in-salt(PIS)solid-state electrolytes,aiming to suppress lithium dendrite growth and improve full-cell performance.The Al_(2)O_(3)coating layer not only refines the wettability of polyimide porous film to PIS,but also performs as a high modulus protective layer to suppress the growth of lithium dendrites.The resulting PI/AO@PIS exhibits a small thickness of only 35μm with an outstanding tensile strength of 11.3 MPa and Young's modulus of 537.6 MPa.In addition,the PI/AO@PIS delivers a high ionic conductivity of 0.1 m S/cm at 25°C.As a result,the PI/AO@PIS enables symmetric Li cells to achieve exceptional cyclability for over 1000 h at 0.1 m A/cm2without noticeable lithium dendrite formation.Moreover,the PI/AO@PIS-based LiFePO4||Li full cells demonstrate outstanding rate performance(125.7 m Ah/g at 5 C)and impressive cycling stability(96.1%capacity retention at 1 C after 200 cycles).This work highlights the efficacy of enhancing the mechanical properties of polymer matrices and extending cell performance through the incorporation of a dense inorganic interface layer.
基金Projects (2005CB724105, 2011CB706801) supported by the National Basic Research Program of ChinaProjects (10477010, 51171089) supported by the National Natural Science Foundation of China+1 种基金Project (2007AA04Z141) supported by the High-Tech Research and Development Program of ChinaProjects (2009ZX04006-041-04, 2011ZX04014-052) supported by the Important National Science & Technology Specific
文摘A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.
基金supported by the National Natural Science Foundation of China(52432007 and 52422212)。
文摘Regulating the crystal texture of zinc deposition is a promising approach to suppress dendrite formation and improve the reversibility of zinc anodes in aqueous zinc-ion batteries.While previous research has mainly focused on developing the Zn(002)texture,investigations into other crystal planes remain scarce.However,exploring alternative crystal planes is crucial for advancing zinc anode performance,as different planes may offer unique advantages in terms of stability and reversibility.Herein,we introduce N-acetylcysteamine(NAC)as an electrolyte additive.It revealed that NAC induces an unexpected exfoliation of the electrodeposited zinc layer,which exhibits preferred orientations along the(102)and(103)planes.Inspired by this anomalous deposition phenomenon,we achieved unconventional Zn(102)and Zn(103)oriented deposition.We demonstrate that NAC molecules adsorb on the Zn surface via thiol groups,modulating the surface energy of different planes to promote the exposure of the two textures.Further characterization,including electrochemical quartz crystal microbalance,electric double-layer capacitance,and contact angle tests,confirms that NAC forms a hydrophobic selfassembled layer,effectively suppressing side reactions.Benefiting from this multifunctional additive,the zinc anode exhibited a long lifespan of 1150 and 780 h under 1 mA cm^(-2)/1 mAh cm^(-2)and 5 mA cm^(-2)/5 mAh cm^(-2),respectively.Moreover,the assembled Zn||V_(2)O_(5)H_(2)O full cells demonstrated prominent electrochemical reversibility.This work not only achieves unconventional Zn(102)and Zn(103)oriented deposition but also provides a novel strategy for designing high-performance zinc-ion batteries.
基金supported by National Natural Science Foundation of China(Nos.52472194,52101243)Natural Science Foundation of Guangdong Province,China(No.2023A1515012619)the Science and Technology Planning Project of Guangzhou(No.202201010565).
文摘Lithium-sulfur batteries(LSBs)are considered as the most promising energy storage technologies owing to their large theoretical energy density(2500Wh/kg)and specific capacity(1675 mAh/g).However,the heavy shuttle effect of polysulfides and the growth of lithium dendrites greatly hinder their further development and commercial application.In this paper,cobalt-molybdenum bimetallic carbides heterostructure(Co_(6)Mo_(6)C_(2)@Co@NC)was successfully prepared through chemical etching procedure of ZIF-67 precursor with sodium molybdate and the subsequent high temperature annealing process.The obtained dodecahedral Co_(6)Mo_(6)C_(2)@Co@NC with hollow and porous structure provides large specific surface area and plentiful active sites,which speeds up the chemisorption and catalytic conversion of polysulfides,thus mitigating the shuttle effect of polysulfides and the generation of lithium dendrites.When applied as the LSBs separator modifier layer,the cell with modified separator present excellent rate capability and durable cycling stability.In particular,the cell with Co_(6)Mo_(6)C_(2)@Co@NC/PP separator can maintain the high capacity of 738 mAh/g at the current density of 2 C and the specific capacity of 782.6 mAh/g after 300 cycles at 0.5 C,with the coulombic efficiency(CE)near to 100%.Moreover,the Co_(6)Mo_(6)C_(2)@Co@NC/PP battery exhibits the impressive capacity of 431 mAh/g in high sulfur loading(4.096 mg/cm^(2))at 0.5 C after 200 cycles.This work paves the way for the development of bimetallic carbides heterostructure multifunctional catalysts for durable Li-S battery applications and reveals the synergistic regulation of polysulfides and lithium dendrites through the optimization of the structure and composition.
基金financially supported by the National Natural Science Foundation of China(22168019 and 52074141)the Major Science and Technology Projects in Yunnan Province(202202AB080014)+1 种基金The authors are grateful to the National Natural Science Foundation of Chinathe Major Science and Technology Projects in Yunnan Province for their support.
文摘Zinc(Zn)-air batteries are widely used in secondary battery research owing to their high theoretical energy density,good electrochemical reversibility,stable discharge performance,and low cost of the anode active material Zn.However,the Zn anode also leads to many challenges,including dendrite growth,deformation,and hydrogen precipitation self-corrosion.In this context,Zn dendrite growth has a greater impact on the cycle lives.In this dissertation,a dendrite growth model for a Zn-air battery was established based on electrochemical phase field theory,and the effects of the charging time,anisotropy strength,and electrolyte temperature on the morphology and growth height of Zn dendrites were studied.A series of experiments was designed with different gradient influencing factors in subsequent experiments to verify the theoretical simulations,including elevated electrolyte temperatures,flowing electrolytes,and pulsed charging.The simulation results show that the growth of Zn dendrites is controlled mainly by diffusion and mass transfer processes,whereas the electrolyte temperature,flow rate,and interfacial energy anisotropy intensity are the main factors.The experimental results show that an optimal electrolyte temperature of 343.15 K,an optimal electrolyte flow rate of 40 ml·min^(-1),and an effective pulse charging mode.
基金supported by Open Foundation of the State Key Laboratory of Refractories and Metallurgy(No.G201711)the National Natural Science Foundation of China(Nos.52104317 and 51874001).
文摘The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of dendritic solidification structures.Combining scanning electron microscopy and energy-dispersive scanning analysis and ANSYS simulation,the high-precision image processing software Mimics Research was utilized to conduct the extraction of dendritic morphologies.Reverse engineering software NX Imageware was employed for the 3D reconstruction of two-dimensional dendritic morphologies,restoring the dendritic characteristics in three-dimensional space.The results demonstrate that in a two-dimensional plane,dendrites connect with each other to form irregularly shaped“ring-like”structures.These dendrites have a thickness greater than 0.1 mm along the Z-axis direction,leading to the envelopment of molten steel by dendrites in a 3D space of at least 0.1 mm.This results in obstructed flow,confirming the“bridging”of dendrites in three-dimensional space,resulting in a tendency for central segregation.Dense and dispersed tiny dendrites,under the influence of heat flow direction,interconnect and continuously grow,gradually forming primary and secondary dendrites in three-dimensional space.After the completion of dendritic solidification and growth,these microdendrites appear dense and dispersed on the two-dimensional plane,providing the nuclei for the formation of new dendrites.When reduction occurs at a solid fraction of 0.46,there is a noticeable decrease in dendritic spacing,resulting in improved central segregation.
基金Project(50871044)supported by the National Natural Science Foundation of ChinaProject(2012M511207)supported by the Postdoctoral Science Foundation of ChinaProject(10122011)supported by the Science Research Foundation of Wuhan Institute Technology,China
文摘Effect of direct current electric field （DCEF） on corrosion behaviour of copper printed circuit board （PCB-Cu）, Cl-ion migration behaviour, dendrites growth under thin electrolyte layer was investigated using potentiodynamic polarization and scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS）. Results indicate that DCEF decreases the corrosion of PCB-Cu;Cl-ions directionally migrate from the negative pole to the positive pole, and enrich on the surface of the positive pole, which causes serious localized corrosion; dendrites grow on the surface of the negative pole, and the rate and scale of dendrite growth become faster and greater with the increase of external voltage and exposure time, respectively.
基金Project (42-QP-009) support by Research Fund of the State Key Laboratory of Solidification Processing,ChinaProject (B08040) supported by the Program of Introducing Talents of Discipline to Universities ("111"Project),China
文摘Nucleation of dendritic primaryα（Al） phase with addition of element Ce and Sr in hypoeutectic Al-7%Si-Mg cast alloy was investigated by using differential scanning calorimetry （DSC） and scanning electron microscopy. DSC results were used to calculate the activation energy and nucleation work of primaryα（Al） phase. The results show that the values of activation energy and nucleation work are decreased and the nucleation frequency is increased with the additions of Ce and Sr to the alloys. Moreover, the grain size of dendriticα（Al） phase is well refined, and the nucleation temperatures of primaryα（Al） dendrites are decreased with the additions of Ce and Sr. The effects of elements Ce and Sr additions on kinetic nucleation of primary α（Al） phases were also discussed in hypoeutectic Al-7%Si-Mg cast alloy.
基金Project(50395100)supported by the National Natural Science Foundation of ChinaProject(NCET-07-0692)supported by the New Century Talents Program of the Ministry of Education,ChinaProject(34-TP-2009)supported by Open Project of State Key Laboratory of Solidification Processing,China
文摘Primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with different diameters.The experimental results show the measured PDAS increases with increasing diameter of the sample.At the growth velocity of 5 μm/s,its value changes from 161.5 μm for the sample with 1.8 mm in diameter to 240.4 μm for the sample with 7 mm in diameter.The strong melt convection in large diameter samples causes a high bulk alloy composition and a high concentration gradient in peritectic β phase,resulting in a larger PDAS.Simultaneously,the high concentration gradient could effectively promote the peritectic transformation,enhancing the dissolution of the thin α dendrite.
