The photocatalytic reduction of CO_(2)presents a promising avenue for carbon fuel conversion.However,the efficiency of charge utilization remains a critical barrier to industrial applications.In this study,we introduc...The photocatalytic reduction of CO_(2)presents a promising avenue for carbon fuel conversion.However,the efficiency of charge utilization remains a critical barrier to industrial applications.In this study,we introduce a tandem design of Bi_(2)WO_(6)-BiOCl with an atomically matched interface,achieving highly efficient photoreduction of CO_(2)to CO.By incorporating WO_(4)^(2-)ions and tuning coordination environment,the(110)facet of BiOCl was in-situ grown on the(200)facet of Bi_(2)WO_(6).Compared to single phases and ball-milling samples,Bi_(2)WO_(6)-BiOCl exhibits a remarkable CO yield of 68.03μmol g^(-1)h^(-1)with a selectivity of 98%.Atomic visualization and coordination analysis confirm the formation of a coherent interface that facilitates charge migration for efficient electron transport.Density functional theory(DFT)calculations and in-situ Fourier transform infrared(FTIR)spectroscopy provide insights into the intrinsic active sites and reaction mechanisms.The proposed lattice engineering strategies offer a new paradigm for the rational design of heterostructures beyond traditional band alignment at the atomic scale.展开更多
Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),a 5 V class high voltage cathode,has been regarded as an attractive candidate to further improve the energy density of lithium-ion battery.The issue simultaneously enabling side st...Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),a 5 V class high voltage cathode,has been regarded as an attractive candidate to further improve the energy density of lithium-ion battery.The issue simultaneously enabling side stability and maintaining high interfacial kinetics,however,has not yet been resolved.Herein,we design a coherent Li_(1.3)A_(l0.3)Ti_(1.7)(PO)_(4)(LATP)layer that is crystally connected to the spinel LNMO host lattices,which offers fast lithium ions transportation as well as enhances the mechanical stability that prevents the particle fracture.Furthermore,the inactive Li_(3)BO_(3)(LBO)coating layer inhibits the corrosion of transition metals and continuous side reactions.Consequently,the coherent-engineered LNMO-LATPLBO cathode material exhibits superior electrochemical cycling stability in a window of 3.0–5.0 V,for example a high-capacity retention that is 89.7%after 500 cycles at 200 m A g-1obtained and enhanced rate performance(85.1 m A h g^(-1)at 800 m A g^(-1))when tested with a LiPF6-based carbonate electrolyte.Our work presents a new approach of engineering 5 V class spinel oxide cathode that combines interfacial coherent crystal lattice design and surface coating.展开更多
The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cemen...The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the potyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H + from hydrolysis of quarts: and OH- from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and onions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- onions are bonded with the hydrated cations such as Ca2+ and Al3+ , which is confirmed by the gel containing Ca and Si on the quartz surface.展开更多
The interface of ceramic particles and metal matrixes extremely impacts the mechanical properties of particle-reinforced metal matrix composites,especially at elevated temperatures.We provide a strategy for constructi...The interface of ceramic particles and metal matrixes extremely impacts the mechanical properties of particle-reinforced metal matrix composites,especially at elevated temperatures.We provide a strategy for constructing extremely fine,in situ-formed coherent nanolamellar solute-twining architectures in a supersaturated MAX/Ni composite to modify the interface,aiming for higher strengths.Through this unique architecture,a coherent interface of ceramic particles and a metal matrix is formed,with an enormous coherent interface known as a ladder interface.The tensile strength at 1023 K is approximately 1 GPa by forming a thermally stable Schwarz crystal structure(<3 nm).Developing heat-tolerant composites using this architecture may enhance the materials’available properties for high-temperature applications.展开更多
The deformation incompatibility of components is a bottleneck restricting the exaltation of the strength and ductility of composites.Herein,the coherent transition interface was designed and produced in hexagonal boro...The deformation incompatibility of components is a bottleneck restricting the exaltation of the strength and ductility of composites.Herein,the coherent transition interface was designed and produced in hexagonal boron nitride nanosheets(BNNSs)/Al composites by reaction sintering route,expecting to re-lieve the deformation incompatibility between BNNSs and Al.It is demonstrated that with the sintering temperature for composites raising from 600℃ to 650℃,700℃ and 750℃,different interface bonding characteristics,which involve nucleation and growth of AlN continuous nanolayer,were confirmed.Fur-thermore,first-principles calculations show that the generation of the coherent transition interface im-proved the interfacial bonding strength of BNNSs/Al composites through covalent bonds.The composites with coherent transition interface exhibit excellent strength-toughness combination in tensile and impact tests.The finite element simulation and in-situ approach under tensile tests were applied to investigate the influence of transition interface structure on deformation behavior of BNNSs/Al composite.It is found that the generation of the transition interface can not only weaken the stress partitioning behavior in the elastic stage,but also constrain the crack initiation and propagation behavior in the elastic-plastic stage and plastic stage,thereby improving the deformation compatibility between BNNSs and Al.The present work provides a novel view into the breakthrough for the trade-offrelationship of strength and ductility by coherent transition interface design in nanocomposites.展开更多
With rapid developments in the field of very large-scale integrated circuits,heat dissipation has emerged as a significant factor that restricts the high-density integration of chips.Due to their high thermal conducti...With rapid developments in the field of very large-scale integrated circuits,heat dissipation has emerged as a significant factor that restricts the high-density integration of chips.Due to their high thermal conductivity and low thermal expansion coefficient,diamond/Cu composites have attracted considerable attention as a promising thermal management material.In this study,a surface tungsten carbide gradient layer coating of diamond particles has been realized using comprehensive magnetron sputtering technology and a heat treatment process.Diamond/Cu composites were prepared using high-temperature and high-pressure technology.The results show that,by adjusting the heat treatment process,tungsten carbide and di-tungsten carbide are generated by an in situ reaction at the tungsten–diamond interface,and W–WC–W_(2)C gradient layer-coated diamond particles were obtained.The diamond/Cu composites were sintered by high-temperature and high-pressure technology,and the density of surface-modified diamond/Cu composites was less than 4 g cm^(-3).The W–WC–W_(2)C@diamond/Cu composites have a thermal diffusivity as high as 331 mm^(2)s^(-1),and their thermal expansion coefficient is as low as 1.76×10^(-6)K^(-1).The interface coherent structure of the gradient layer-coated diamond/copper composite can effectively improve the interface heat transport efficiency.展开更多
Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the...Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the size of derivatives and phase engineering has not been clarified so far.Herein,a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages.It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOFs crystals and subsequently affects the dielectric polarization due to the phase hybridization with tunable coherent interfaces and heterojunctions owing to size-dependent oxidation motion,yielding to satisfied microwave attenuation with an optimal reflection loss of-50.6 d B and effective bandwidth of 6.6 GHz.Meanwhile,the effect of phase hybridization on dielectric polarization is deeply visualized,and the simulated calculation and electron holograms demonstrate that dielectric polarization is shown to be dominant dissipation mechanism in determining microwave absorption.This spatial confined growth strategy provides a versatile methodology for manipulating the size of MOFs derivatives and the understanding of size-dependent oxidation-induced phase hybridization offers a precise inspiration in optimizing dielectric polarization and microwave attenuation in theory.展开更多
We designed a novel Co-free AlCrFe2Ni2Ti0.5 high-entropy alloy(HEA)that features an excellent combination of strength and ductility in this study.The as-cast AlCrFe2Ni2Ti0.5 alloy showed equiaxed grains undergoing spi...We designed a novel Co-free AlCrFe2Ni2Ti0.5 high-entropy alloy(HEA)that features an excellent combination of strength and ductility in this study.The as-cast AlCrFe2Ni2Ti0.5 alloy showed equiaxed grains undergoing spinodal decomposition,which consisted of ultrafine-grained laminated body-centered cubic(bcc)phases and an ordered body-centered cubic(b2)phase,and some precipitates embedded in the b2 matrix.The bcc and b2 phases also feature a coherent interface.This unique structure impedes mobile dislocations and hinders the formation of cracks,thereby giving the AlCrFe2Ni2Ti0.5 HEA both high strength and plasticity.At room temperature,the as-cast AlCrFe2Ni2Ti0.5 alloy exhibited a compressive yield strength of 1714 MPa,an ultimate strength of 3307 MPa,and an elongation of 43%.These mechanical properties are superior to those of most reported HEAs.展开更多
Diamond,with ultrahigh hardness,high wear resistance,high thermal conductivity,and so forth,has attracted worldwide attention.However,researchers found emergent reactions at the interfaces between diamond and ferrous ...Diamond,with ultrahigh hardness,high wear resistance,high thermal conductivity,and so forth,has attracted worldwide attention.However,researchers found emergent reactions at the interfaces between diamond and ferrous materials,which significantly affects the performance of diamond-based devices.Herein,combing experiments and theoretical calculations,taking diamond–iron(Fe)interface as a prototype,the counter-diffusion mechanism of Fe/carbon atoms has been established.Surprisingly,it is identified that Fe and diamond first form a coherent interface,and then Fe atoms diffuse into diamond and prefer the carbon vacancies sites.Meanwhile,the relaxed carbon atoms diffuse into the Fe lattice,forming Fe_(3)C.Moreover,graphite is observed at the Fe_(3)C surface when Fe_(3)C is over-saturated by carbon atoms.The present findings are expected to offer new insights into the atomic mechanism for diamondferrous material's interfacial reactions,benefiting diamond-based device applications.展开更多
This study revealed that the presence of Cr and Ni in stainless steel is one of the leading causes for the weakening of the Mg/Fe interface when using a traditional Mg-Zn-Al(i.e.,AZ61)filler wire.By using a novel Mg-G...This study revealed that the presence of Cr and Ni in stainless steel is one of the leading causes for the weakening of the Mg/Fe interface when using a traditional Mg-Zn-Al(i.e.,AZ61)filler wire.By using a novel Mg-Gd-Y-Zr filler wire without Al,the interfacial structure between Mg/Fe was optimized,and the joint integrity was significantly improved.Using advanced multiscale characterization tools,the coherent matching mechanism of rare earth elements in regulating Mg/Fe interfacial compounds was clarified.The results showed that Gd and Y exhibited lower diffusion activation energy and faster diffusion rates in Fe compared to Al resulting in IMCs with more stiffness and mechanical integrity than Al-Mg compounds that are generated at the Mg/Fe interface when using the AZ61 filler wire.High-resolution TEM results revealed that the lattice distortion caused by the diffusion of metal elements changes the original semi-coherent matching interfaces of(0001)_(HCP-Mg)and(012)_(BCC-Mg24(Y,Gd)5),as well as lattice planes of(012)_(BCC-Mg24(Y,Gd)5)and(5723)_(HCP-Fe17(Y,Gd)2)into a coherent matching interface,which is known to improve mechanical strength.Although lattice planes of(5723)_(HCP-Fe17(Y,Gd)2)and(111)_(BCC-Fe)were found to be incoherent interfaces,it was found that Gd,Y,and Zr with larger atomic radii compared to Al diffused into the bulk Fe to form a wide range of(Fe,Gd,Y,Zr,Cr,Ni,Mn)interstitial solid solutions,which helped strengthen the integrity of the joint.The results showed that the load bearing capacity of the AZ31B/Mg-RE/316 L joint was about 290 N/mm,which is 2.5 times that of the AZ31B/AZ61/316 L joints,which was measured at 115 N/mm.展开更多
A single crystal Cu-1wt.%Fe alloy with finely dispersed iron-rich nanoparticles which keep coherent interface with the copper matrix was prepared under directional solidification.Formation of nanoparticles in the allo...A single crystal Cu-1wt.%Fe alloy with finely dispersed iron-rich nanoparticles which keep coherent interface with the copper matrix was prepared under directional solidification.Formation of nanoparticles in the alloy melt was investigated by performing differential scanning calorimeter tests and designed water quenching experiment at a certain temperature.Results show that iron-rich nanoparticles are formed in the Cu-1wt.%Fe alloy melt before primaryα-Cu forms,which is not consistent with equilibrium phase diagram.Mechanism that iron-rich nanoparticles are uniformly captured in the matrix was described,which is that numerous nanoparticles follow Brownian motions and are engulfed in the solidified matrix which makes it possible to form uniformly distributed nanoparticles reinforced single crystal Cu-1wt.%Fe alloy.展开更多
Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck fo...Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions.To overcome this challenge,we designed a vanadium oxide/nitride(V_(2)O_(3)/VN)hybrid electrocatalyst in which V_(2)O_(3)and VN coex-ist coherently at the heterogeneous interface.Since single-phase V_(2)O_(3)and VN exhibit different surface catalytic kinetics for NRR,the V_(2)O_(3)/VN hybrid elec-trocatalyst can provide alternating reaction pathways,selecting a lower energy pathway for each material in the serial NRR pathway.As a result,the ammo-nia yield of the V_(2)O_(3)/VN hybrid electrocatalyst was 219.6µg h^(-1)cm^(-2),and the Faradaic efficiency was 18.9%,which is much higher than that of single-phase VN,V_(2)O_(3),and VNxOy solid solution catalysts without heterointerfaces.Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low-energy reaction pathway through the migration and adsorption of interme-diate species.Therefore,the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient elec-trochemical catalysts that induce steps favorable for the efficient low-energy progression of NRR.展开更多
TiAl plays a crucial role in the field of aero‐engine as a new lightweight high‐temperature alloy.The γ/α_(2) lamellar TiAl single crystals exhibit the highest recorded plasticity,much higher than the soft phaseγ...TiAl plays a crucial role in the field of aero‐engine as a new lightweight high‐temperature alloy.The γ/α_(2) lamellar TiAl single crystals exhibit the highest recorded plasticity,much higher than the soft phaseγ‐TiAl.This suggests that the hard phaseα_(2)‐Ti_(3)Al may have a unique plastic deformation mechanism,which is important for essentially understanding the origin of unusual plasticity and further improving the mechanical properties of TiAl.Here,we found the dynamic sequential phase transformation between HCP and FCC under shear loading in α_(2)‐Ti_(3)Al,which is a novel plastic deformation mechanism comparable to twinning.We attribute this to the bond‐breaking formation process called“catching bond”,which is the origin of atomic mechanism of phase transformation occurrence.This“catching bond”process is an effective way of energy dissipation that can release the internal stress while maintaining the integrity of structure.The higher cleavage energy than the generalized stacking fault energy(GSFE)guarantees the continuity of phase transformation during shearing.Moreover,the γ/α_(2) coherent interface can reduce the GSFE,thus decreasing the critical resolved shear stress(CRSS)of the phase transformation by 35%,which suggests that the phase transformation induced plastic mechanism easily occurs in the lamellar structure.This study reveals the plastic deformation mechanism of α_(2)‐Ti_(3)Al and explores the role of γ/α_(2) coherent interface on the plasticity,which is expected to provide guidance for further improving the mechanical properties of TiAl alloys.展开更多
基金supported by the National Key R&D Program of China(No.2021YFA1200201)the Beijing Outstanding Young Scientists Projects(No.BJJWZYJH01201910005018)+1 种基金The Basic Science Center Program for Multiphase Evolution in Hypergravity of the National Natural Science Foundation of China(No.51988101)the National Natural Science Foundation of China(Nos.52071003 and 91860202)。
文摘The photocatalytic reduction of CO_(2)presents a promising avenue for carbon fuel conversion.However,the efficiency of charge utilization remains a critical barrier to industrial applications.In this study,we introduce a tandem design of Bi_(2)WO_(6)-BiOCl with an atomically matched interface,achieving highly efficient photoreduction of CO_(2)to CO.By incorporating WO_(4)^(2-)ions and tuning coordination environment,the(110)facet of BiOCl was in-situ grown on the(200)facet of Bi_(2)WO_(6).Compared to single phases and ball-milling samples,Bi_(2)WO_(6)-BiOCl exhibits a remarkable CO yield of 68.03μmol g^(-1)h^(-1)with a selectivity of 98%.Atomic visualization and coordination analysis confirm the formation of a coherent interface that facilitates charge migration for efficient electron transport.Density functional theory(DFT)calculations and in-situ Fourier transform infrared(FTIR)spectroscopy provide insights into the intrinsic active sites and reaction mechanisms.The proposed lattice engineering strategies offer a new paradigm for the rational design of heterostructures beyond traditional band alignment at the atomic scale.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20200800)the National Natural Science Foundation of China(22209075,51902165,12004145)+1 种基金the Natural Science Foundation of Jiangxi Province(20212BAB214032,20192ACBL20048)the Key Science and Technology Plan Project of Ji’an City(20211-015311)。
文摘Spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),a 5 V class high voltage cathode,has been regarded as an attractive candidate to further improve the energy density of lithium-ion battery.The issue simultaneously enabling side stability and maintaining high interfacial kinetics,however,has not yet been resolved.Herein,we design a coherent Li_(1.3)A_(l0.3)Ti_(1.7)(PO)_(4)(LATP)layer that is crystally connected to the spinel LNMO host lattices,which offers fast lithium ions transportation as well as enhances the mechanical stability that prevents the particle fracture.Furthermore,the inactive Li_(3)BO_(3)(LBO)coating layer inhibits the corrosion of transition metals and continuous side reactions.Consequently,the coherent-engineered LNMO-LATPLBO cathode material exhibits superior electrochemical cycling stability in a window of 3.0–5.0 V,for example a high-capacity retention that is 89.7%after 500 cycles at 200 m A g-1obtained and enhanced rate performance(85.1 m A h g^(-1)at 800 m A g^(-1))when tested with a LiPF6-based carbonate electrolyte.Our work presents a new approach of engineering 5 V class spinel oxide cathode that combines interfacial coherent crystal lattice design and surface coating.
基金Funded by Natural Science Foundation of China (No. 49802004)
文摘The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the potyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H + from hydrolysis of quarts: and OH- from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and onions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- onions are bonded with the hydrated cations such as Ca2+ and Al3+ , which is confirmed by the gel containing Ca and Si on the quartz surface.
基金supported financially by the Beijing Natural Science Foundation(No.2212046)the National Natural Science Foundation of China(Nos.51871011 and 51572017)+2 种基金the Research Fund for Commercialization of Major Scientific and Technological Achievements of Hebei Province(No.22281006Z)the Beijing Government Funds for the Constructive Project of Central UniversitiesThe financial supports by them are greatly appreciated.
文摘The interface of ceramic particles and metal matrixes extremely impacts the mechanical properties of particle-reinforced metal matrix composites,especially at elevated temperatures.We provide a strategy for constructing extremely fine,in situ-formed coherent nanolamellar solute-twining architectures in a supersaturated MAX/Ni composite to modify the interface,aiming for higher strengths.Through this unique architecture,a coherent interface of ceramic particles and a metal matrix is formed,with an enormous coherent interface known as a ladder interface.The tensile strength at 1023 K is approximately 1 GPa by forming a thermally stable Schwarz crystal structure(<3 nm).Developing heat-tolerant composites using this architecture may enhance the materials’available properties for high-temperature applications.
基金This work was financially supported by the Chinese Na-tional Natural Science Fund for Distinguished Young Scholars(No.52025015)the Chinese National Natural Science Foundation Nos.51771130,52071230 and 52101181)+2 种基金the Tianjin Youth Tal-ent Support Program,the Tianjin Natural Science Funds for Dis-tinguished Young Scholars(No.17JCJQJC44300)the Tianjin Sci-ence and Technology Support Project(No.17ZXCLGX00060)the China Postdoctoral Science Foundation Nos.2020M670648 and 2021T140505).
文摘The deformation incompatibility of components is a bottleneck restricting the exaltation of the strength and ductility of composites.Herein,the coherent transition interface was designed and produced in hexagonal boron nitride nanosheets(BNNSs)/Al composites by reaction sintering route,expecting to re-lieve the deformation incompatibility between BNNSs and Al.It is demonstrated that with the sintering temperature for composites raising from 600℃ to 650℃,700℃ and 750℃,different interface bonding characteristics,which involve nucleation and growth of AlN continuous nanolayer,were confirmed.Fur-thermore,first-principles calculations show that the generation of the coherent transition interface im-proved the interfacial bonding strength of BNNSs/Al composites through covalent bonds.The composites with coherent transition interface exhibit excellent strength-toughness combination in tensile and impact tests.The finite element simulation and in-situ approach under tensile tests were applied to investigate the influence of transition interface structure on deformation behavior of BNNSs/Al composite.It is found that the generation of the transition interface can not only weaken the stress partitioning behavior in the elastic stage,but also constrain the crack initiation and propagation behavior in the elastic-plastic stage and plastic stage,thereby improving the deformation compatibility between BNNSs and Al.The present work provides a novel view into the breakthrough for the trade-offrelationship of strength and ductility by coherent transition interface design in nanocomposites.
基金National Natural Science Foundation of China(Grant No.52072327)the China National Key R&D Program(2021YFB3701802)+6 种基金Scientific and Technological Projects of Henan Province(No.232102231050)the Higher Education and Teaching Reformation Project(2014SJGLX064)the Project for Work-station of Zhongyuan scholars of Henan Province(Nos.214400510002,224400510023)the Science and Technology Major Project of Henan Province(No.221100230300)the Postgraduate Education Reform and QualityAcademic Degrees&Graduate Education Reform Project of Henan Province(No.2021SJGLX060Y)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(No.YJS2022JD34)the Science and Technology on Plasma Physics Laboratory(Grant No.JCKYS2021212010).
文摘With rapid developments in the field of very large-scale integrated circuits,heat dissipation has emerged as a significant factor that restricts the high-density integration of chips.Due to their high thermal conductivity and low thermal expansion coefficient,diamond/Cu composites have attracted considerable attention as a promising thermal management material.In this study,a surface tungsten carbide gradient layer coating of diamond particles has been realized using comprehensive magnetron sputtering technology and a heat treatment process.Diamond/Cu composites were prepared using high-temperature and high-pressure technology.The results show that,by adjusting the heat treatment process,tungsten carbide and di-tungsten carbide are generated by an in situ reaction at the tungsten–diamond interface,and W–WC–W_(2)C gradient layer-coated diamond particles were obtained.The diamond/Cu composites were sintered by high-temperature and high-pressure technology,and the density of surface-modified diamond/Cu composites was less than 4 g cm^(-3).The W–WC–W_(2)C@diamond/Cu composites have a thermal diffusivity as high as 331 mm^(2)s^(-1),and their thermal expansion coefficient is as low as 1.76×10^(-6)K^(-1).The interface coherent structure of the gradient layer-coated diamond/copper composite can effectively improve the interface heat transport efficiency.
基金This work was financially supported by the National Natural Science Foundation of China(U21A2093 and 52102370)the Natural Science Foundation of Shaanxi Province(2022JM-260)+2 种基金the Shanghai Key Laboratory of R&D for Metallic Functional Materials(2021-01)and Open Fund of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(JBGS014)Open access funding provided by Shanghai Jiao Tong University
文摘Precisely reducing the size of metal-organic frameworks(MOFs)derivatives is an effective strategy to manipulate their phase engineering owing to size-dependent oxidation;however,the underlying relationship between the size of derivatives and phase engineering has not been clarified so far.Herein,a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages.It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOFs crystals and subsequently affects the dielectric polarization due to the phase hybridization with tunable coherent interfaces and heterojunctions owing to size-dependent oxidation motion,yielding to satisfied microwave attenuation with an optimal reflection loss of-50.6 d B and effective bandwidth of 6.6 GHz.Meanwhile,the effect of phase hybridization on dielectric polarization is deeply visualized,and the simulated calculation and electron holograms demonstrate that dielectric polarization is shown to be dominant dissipation mechanism in determining microwave absorption.This spatial confined growth strategy provides a versatile methodology for manipulating the size of MOFs derivatives and the understanding of size-dependent oxidation-induced phase hybridization offers a precise inspiration in optimizing dielectric polarization and microwave attenuation in theory.
基金the National Key Research and Development Program of China(No.2017YFA0403803)the National Natural Science Foundation of China(Nos.51525401,51774065,51601028,and 51690163).
文摘We designed a novel Co-free AlCrFe2Ni2Ti0.5 high-entropy alloy(HEA)that features an excellent combination of strength and ductility in this study.The as-cast AlCrFe2Ni2Ti0.5 alloy showed equiaxed grains undergoing spinodal decomposition,which consisted of ultrafine-grained laminated body-centered cubic(bcc)phases and an ordered body-centered cubic(b2)phase,and some precipitates embedded in the b2 matrix.The bcc and b2 phases also feature a coherent interface.This unique structure impedes mobile dislocations and hinders the formation of cracks,thereby giving the AlCrFe2Ni2Ti0.5 HEA both high strength and plasticity.At room temperature,the as-cast AlCrFe2Ni2Ti0.5 alloy exhibited a compressive yield strength of 1714 MPa,an ultimate strength of 3307 MPa,and an elongation of 43%.These mechanical properties are superior to those of most reported HEAs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274371,62271450,U21A2070,21805247,12074345)Cross-Disciplinary Innovative Research Group Project of Henan Province(Grant No.232300421004).
文摘Diamond,with ultrahigh hardness,high wear resistance,high thermal conductivity,and so forth,has attracted worldwide attention.However,researchers found emergent reactions at the interfaces between diamond and ferrous materials,which significantly affects the performance of diamond-based devices.Herein,combing experiments and theoretical calculations,taking diamond–iron(Fe)interface as a prototype,the counter-diffusion mechanism of Fe/carbon atoms has been established.Surprisingly,it is identified that Fe and diamond first form a coherent interface,and then Fe atoms diffuse into diamond and prefer the carbon vacancies sites.Meanwhile,the relaxed carbon atoms diffuse into the Fe lattice,forming Fe_(3)C.Moreover,graphite is observed at the Fe_(3)C surface when Fe_(3)C is over-saturated by carbon atoms.The present findings are expected to offer new insights into the atomic mechanism for diamondferrous material's interfacial reactions,benefiting diamond-based device applications.
基金sponsored by the National Key Research and Development Program of China(2022YFB4600900)the National Natural Science Foundation of China(No.U1960111/52375309)the Liaoning Province Applied Basic Research Program Project(2023JH2/101300157)。
文摘This study revealed that the presence of Cr and Ni in stainless steel is one of the leading causes for the weakening of the Mg/Fe interface when using a traditional Mg-Zn-Al(i.e.,AZ61)filler wire.By using a novel Mg-Gd-Y-Zr filler wire without Al,the interfacial structure between Mg/Fe was optimized,and the joint integrity was significantly improved.Using advanced multiscale characterization tools,the coherent matching mechanism of rare earth elements in regulating Mg/Fe interfacial compounds was clarified.The results showed that Gd and Y exhibited lower diffusion activation energy and faster diffusion rates in Fe compared to Al resulting in IMCs with more stiffness and mechanical integrity than Al-Mg compounds that are generated at the Mg/Fe interface when using the AZ61 filler wire.High-resolution TEM results revealed that the lattice distortion caused by the diffusion of metal elements changes the original semi-coherent matching interfaces of(0001)_(HCP-Mg)and(012)_(BCC-Mg24(Y,Gd)5),as well as lattice planes of(012)_(BCC-Mg24(Y,Gd)5)and(5723)_(HCP-Fe17(Y,Gd)2)into a coherent matching interface,which is known to improve mechanical strength.Although lattice planes of(5723)_(HCP-Fe17(Y,Gd)2)and(111)_(BCC-Fe)were found to be incoherent interfaces,it was found that Gd,Y,and Zr with larger atomic radii compared to Al diffused into the bulk Fe to form a wide range of(Fe,Gd,Y,Zr,Cr,Ni,Mn)interstitial solid solutions,which helped strengthen the integrity of the joint.The results showed that the load bearing capacity of the AZ31B/Mg-RE/316 L joint was about 290 N/mm,which is 2.5 times that of the AZ31B/AZ61/316 L joints,which was measured at 115 N/mm.
文摘A single crystal Cu-1wt.%Fe alloy with finely dispersed iron-rich nanoparticles which keep coherent interface with the copper matrix was prepared under directional solidification.Formation of nanoparticles in the alloy melt was investigated by performing differential scanning calorimeter tests and designed water quenching experiment at a certain temperature.Results show that iron-rich nanoparticles are formed in the Cu-1wt.%Fe alloy melt before primaryα-Cu forms,which is not consistent with equilibrium phase diagram.Mechanism that iron-rich nanoparticles are uniformly captured in the matrix was described,which is that numerous nanoparticles follow Brownian motions and are engulfed in the solidified matrix which makes it possible to form uniformly distributed nanoparticles reinforced single crystal Cu-1wt.%Fe alloy.
基金National Research Foundation of Korea,Grant/Award Numbers:2022R1A2C1012419,2022R1A2C1011559,2022R1C1C1007004。
文摘Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions.To overcome this challenge,we designed a vanadium oxide/nitride(V_(2)O_(3)/VN)hybrid electrocatalyst in which V_(2)O_(3)and VN coex-ist coherently at the heterogeneous interface.Since single-phase V_(2)O_(3)and VN exhibit different surface catalytic kinetics for NRR,the V_(2)O_(3)/VN hybrid elec-trocatalyst can provide alternating reaction pathways,selecting a lower energy pathway for each material in the serial NRR pathway.As a result,the ammo-nia yield of the V_(2)O_(3)/VN hybrid electrocatalyst was 219.6µg h^(-1)cm^(-2),and the Faradaic efficiency was 18.9%,which is much higher than that of single-phase VN,V_(2)O_(3),and VNxOy solid solution catalysts without heterointerfaces.Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low-energy reaction pathway through the migration and adsorption of interme-diate species.Therefore,the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient elec-trochemical catalysts that induce steps favorable for the efficient low-energy progression of NRR.
基金supported by the National Natural Science Foundation of China(No.92463301,92463309,92163215 and 92163212)the Natural Science Foundation of Hubei Province of China(No.2023AFB175).
文摘TiAl plays a crucial role in the field of aero‐engine as a new lightweight high‐temperature alloy.The γ/α_(2) lamellar TiAl single crystals exhibit the highest recorded plasticity,much higher than the soft phaseγ‐TiAl.This suggests that the hard phaseα_(2)‐Ti_(3)Al may have a unique plastic deformation mechanism,which is important for essentially understanding the origin of unusual plasticity and further improving the mechanical properties of TiAl.Here,we found the dynamic sequential phase transformation between HCP and FCC under shear loading in α_(2)‐Ti_(3)Al,which is a novel plastic deformation mechanism comparable to twinning.We attribute this to the bond‐breaking formation process called“catching bond”,which is the origin of atomic mechanism of phase transformation occurrence.This“catching bond”process is an effective way of energy dissipation that can release the internal stress while maintaining the integrity of structure.The higher cleavage energy than the generalized stacking fault energy(GSFE)guarantees the continuity of phase transformation during shearing.Moreover,the γ/α_(2) coherent interface can reduce the GSFE,thus decreasing the critical resolved shear stress(CRSS)of the phase transformation by 35%,which suggests that the phase transformation induced plastic mechanism easily occurs in the lamellar structure.This study reveals the plastic deformation mechanism of α_(2)‐Ti_(3)Al and explores the role of γ/α_(2) coherent interface on the plasticity,which is expected to provide guidance for further improving the mechanical properties of TiAl alloys.
