The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing t...The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.展开更多
In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in ...In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.展开更多
The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that format...The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.展开更多
As one of the heterostructures,the layered structure has attracted extensive research interest as it achieves superior properties to individual components.The layer interface is considered a critical fac-tor in determ...As one of the heterostructures,the layered structure has attracted extensive research interest as it achieves superior properties to individual components.The layer interface is considered a critical fac-tor in determining the mechanical properties of layered metals,where heterogeneity across the interface results in the strengthening of the soft layer and forming an interfacial stress gradient in the hard layer.However,there is still limited research associated with the formation of interfacial stress gradients in the hard layer,as stress measurement at high spatial resolution remains technically challenging.In the present study,we experimentally quantified the formation of interfacial stress gradients in the Ti layer of Ti/Al layered metal upon tension using in-situ high-energy X-ray diffraction(XRD).The analysis cou-pling in-situ high-energy XRD and in-situ electron back-scattered diffraction(EBSD)suggested that the interfacial stress gradient in the Ti layer rapidly rose as the Al layer was insufficient to accommodate the deformation of Ti.During the later deformation stage,collective effects of dislocation motion and geometrically necessary dislocation(GND)accumulation in the Al layer determined the evolution of in-terfacial stress gradients.The maximum interfacial stress gradient is below 0.4 MPa/μm in Ti layers,with a constant range width of 35μm independent of the macroscopic strain.The present study therefore opens a new window to local stress modification using incompatible component deformation,which is instructive for the design and fabrication of high-performance layered metals.展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and g...In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.展开更多
When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nat...When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.展开更多
Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditio...Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.展开更多
Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and ...Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.展开更多
When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent ex...When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.展开更多
Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel output...Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel outputs with low energy consumption.However,it presents significant challenges for maintaining the coherent input,scaling the operation rates beyond 10 GHz,and ensuring the effective extraction of functional configuration simultaneously.We propose an optical feature extraction engine(OFE^(2)),which is composed of a diffraction operator and a data preparation module,powering high-speed feature extraction for both image and temporal series tasks.This OFE^(2)can achieve a core latency of less than 250.5 ps;in addition,it can reach a throughput of 250 GOPS and an efficiency of 2.06 TOPS/W.Supported by the OFE^(2),a novel feature extraction paradigm is emerging,enabling high-speed,low-latency service access for applications in scene recognition,medical assistance,and digital finance.展开更多
Face-centered cubic(FCC)equi-atomic multi-principal element alloys(MPEAs)exhibit excellent mechan-ical properties over a broad temperature range from cryogenic temperatures(CTs)to room temperature(RT).Specifically,whi...Face-centered cubic(FCC)equi-atomic multi-principal element alloys(MPEAs)exhibit excellent mechan-ical properties over a broad temperature range from cryogenic temperatures(CTs)to room temperature(RT).Specifically,while the deformation mechanism is dominated solely by dislocation slip at RT,the re-duction in stacking fault energy(SFE)at CTs leads to enhanced strain hardening with deformation twin-ning.This study employs in-situ neutron diffraction to reveal the temperature-dependent deformation be-havior of the FCC/body-centered cubic(BCC)dual-phase(DP)Al7(CoNiV)93 medium-entropy alloy(MEA),which possesses a matrix exhibiting deformation behavior analogous to that of representative equi-atomic MPEAs.Alongside the increased lattice friction stress associated with reduced temperature as a thermal component,deformation twinning at liquid nitrogen temperature(LNT)facilitates dislocation activity in the FCC matrix,leading to additional strain hardening induced by the dynamic Hall-Petch effect.This would give the appearance that the improved strengthening/hardening behaviors at LNT,compared to RT,are primarily attributable to the FCC phase.In contrast,the BCC precipitates are governed solely by dislocation slip for plastic deformation at both 77 K and 298 K,exhibiting a similar trend in dislocation density evolution.Nevertheless,empirical and quantitative findings indicate that the intrinsically high Peierls-Nabarro barriers in the BCC precipitates exhibit pronounced temperature-dependent lattice fric-tion stress,suggesting that the BCC precipitates play a more significant role in the temperature-dependent strengthening/hardening behaviors for the DP-MEA.This study provides a comprehensive understanding of deformation behavior by thoroughly analyzing temperature-dependent strengthening/hardening mech-anisms across various DP-MPEA systems,offering valuable guidelines for future alloy design.展开更多
An analytical expression for focal intensity is derived for arbitrary surface profiles and arbitrary groove patterns of compressor gratings.The expression is valid for different compressor designs:plane and out-of-pla...An analytical expression for focal intensity is derived for arbitrary surface profiles and arbitrary groove patterns of compressor gratings.The expression is valid for different compressor designs:plane and out-of-plane compressors,symmetric and asymmetric compressors(compressors composed by two not-identical pairs of gratings)and a twograting compressor.It is shown that the quality requirements for the optics used to write a grating are higher than for the grating.The focal intensity can be maximized by rotating each grating around its normal by 180 degrees.Moreover,it may be increased to maximum by interchanging any two gratings in the compressor,because imperfections of an individual grating do not additively affect the focal intensity.The intensity decrease is proportional to the squared pulse spectrum width and the squared total distortions of the second and third gratings of the four-grating compressor and the total distortions of two gratings of the two-grating compressor.展开更多
The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were...The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.展开更多
The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,com...The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.展开更多
Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current l...Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.展开更多
Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and ...Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.展开更多
基金National Key R&D Program of China(2023YFB3711904,2022YFA1603801)National Natural Science Foundation of China(12404230,52471181,52301213,52130108,52471005)+2 种基金National Nature Science Foundation of Zhejiang Province(LY23E010002)Open Fund of the China Spallation Neutron Source,Songshan Lake Science City(KFKT2023B11)Guangdong Basic and Applied Basic Research Foundation(2022A1515110805,2024A1515010878)。
文摘The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.
基金This work was supported by the National Natural Science Foundation of China under grant No.50171040.
文摘In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.
文摘The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.
基金supported by the National Key Re-search&Development Plan(No.2022YFE0110600)the National Natural Science Foundation of China(Nos.52201122,92263201,52171117,and 52371113)+1 种基金the Jiangsu Funding Program for Excel-lent Postdoctoral Talent(No.2022ZB366)the China Postdoc-toral Science Foundation Funded Project(No.2023M731636).
文摘As one of the heterostructures,the layered structure has attracted extensive research interest as it achieves superior properties to individual components.The layer interface is considered a critical fac-tor in determining the mechanical properties of layered metals,where heterogeneity across the interface results in the strengthening of the soft layer and forming an interfacial stress gradient in the hard layer.However,there is still limited research associated with the formation of interfacial stress gradients in the hard layer,as stress measurement at high spatial resolution remains technically challenging.In the present study,we experimentally quantified the formation of interfacial stress gradients in the Ti layer of Ti/Al layered metal upon tension using in-situ high-energy X-ray diffraction(XRD).The analysis cou-pling in-situ high-energy XRD and in-situ electron back-scattered diffraction(EBSD)suggested that the interfacial stress gradient in the Ti layer rapidly rose as the Al layer was insufficient to accommodate the deformation of Ti.During the later deformation stage,collective effects of dislocation motion and geometrically necessary dislocation(GND)accumulation in the Al layer determined the evolution of in-terfacial stress gradients.The maximum interfacial stress gradient is below 0.4 MPa/μm in Ti layers,with a constant range width of 35μm independent of the macroscopic strain.The present study therefore opens a new window to local stress modification using incompatible component deformation,which is instructive for the design and fabrication of high-performance layered metals.
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金supported by Science Fund for Creative Research Groups of the National Natural Science Foundation of China,No.42321002。
文摘In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.
基金Project supported by Science and Technology Project of Guangdong(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)National Funded Postdoctoral Researcher Program(Grant No.GZB20240785)。
文摘When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.
基金supported by the West Light Project,CAS(xbzg-zdsys-202206)the National Key Research and Development Program of China(2021YFA1401003)+1 种基金the National Natural Science Foundation of China(NSFC)(62222513,U24A6010,and U24A20317)the Sichuan Engineering Research Center of Digital Materials.
文摘Optical monitoring of object position and alignment with nanoscale precision is critical for ultra-precision measurement applications,such as micro/nano-fabrication,weak force sensing,and micro-scopic imaging.Traditional optical nanometry methods often rely on precision nanostructure fabrication,multi-beam interferometry,or complex post-processing algorithms,which can limit their practical use.In this study,we introduced a simplified and robust quantum measurement technique with an achievable resolution of 2.2 pm and an experimental demonstration of 1 nm resolution,distinguishing it from conventional interferometry,which depended on multiple reference beams.We designed a metasurface substrate with a mode-conversion function,in which an incident Gaussian beam is converted into higher-order transverse electromagnetic mode(TEM)modes.A theoretical analysis,including calculations of the Fisher information,demonstrated that the accuracy was maintained for nanoscale displacements.In conclusion,the study findings provide a new approach for precise alignment and metrology of nanofabrication and other advanced applications.
文摘Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)the National Funded Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0203600)the National Natural Science Foundation of China(Grant No.62135009).
文摘Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel outputs with low energy consumption.However,it presents significant challenges for maintaining the coherent input,scaling the operation rates beyond 10 GHz,and ensuring the effective extraction of functional configuration simultaneously.We propose an optical feature extraction engine(OFE^(2)),which is composed of a diffraction operator and a data preparation module,powering high-speed feature extraction for both image and temporal series tasks.This OFE^(2)can achieve a core latency of less than 250.5 ps;in addition,it can reach a throughput of 250 GOPS and an efficiency of 2.06 TOPS/W.Supported by the OFE^(2),a novel feature extraction paradigm is emerging,enabling high-speed,low-latency service access for applications in scene recognition,medical assistance,and digital finance.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(Nos.NRF-2021R1A2C3006662,NRF-2022R1A5A1030054,and RS-2023-00281246)supported by the Basic Science Research Program‘Fostering the Next Generation of Researchers(Ph.D.Candidate)’through the NRF funded by the Ministry of Edu-cation(No.RS-2023-00275651).
文摘Face-centered cubic(FCC)equi-atomic multi-principal element alloys(MPEAs)exhibit excellent mechan-ical properties over a broad temperature range from cryogenic temperatures(CTs)to room temperature(RT).Specifically,while the deformation mechanism is dominated solely by dislocation slip at RT,the re-duction in stacking fault energy(SFE)at CTs leads to enhanced strain hardening with deformation twin-ning.This study employs in-situ neutron diffraction to reveal the temperature-dependent deformation be-havior of the FCC/body-centered cubic(BCC)dual-phase(DP)Al7(CoNiV)93 medium-entropy alloy(MEA),which possesses a matrix exhibiting deformation behavior analogous to that of representative equi-atomic MPEAs.Alongside the increased lattice friction stress associated with reduced temperature as a thermal component,deformation twinning at liquid nitrogen temperature(LNT)facilitates dislocation activity in the FCC matrix,leading to additional strain hardening induced by the dynamic Hall-Petch effect.This would give the appearance that the improved strengthening/hardening behaviors at LNT,compared to RT,are primarily attributable to the FCC phase.In contrast,the BCC precipitates are governed solely by dislocation slip for plastic deformation at both 77 K and 298 K,exhibiting a similar trend in dislocation density evolution.Nevertheless,empirical and quantitative findings indicate that the intrinsically high Peierls-Nabarro barriers in the BCC precipitates exhibit pronounced temperature-dependent lattice fric-tion stress,suggesting that the BCC precipitates play a more significant role in the temperature-dependent strengthening/hardening behaviors for the DP-MEA.This study provides a comprehensive understanding of deformation behavior by thoroughly analyzing temperature-dependent strengthening/hardening mech-anisms across various DP-MPEA systems,offering valuable guidelines for future alloy design.
文摘An analytical expression for focal intensity is derived for arbitrary surface profiles and arbitrary groove patterns of compressor gratings.The expression is valid for different compressor designs:plane and out-of-plane compressors,symmetric and asymmetric compressors(compressors composed by two not-identical pairs of gratings)and a twograting compressor.It is shown that the quality requirements for the optics used to write a grating are higher than for the grating.The focal intensity can be maximized by rotating each grating around its normal by 180 degrees.Moreover,it may be increased to maximum by interchanging any two gratings in the compressor,because imperfections of an individual grating do not additively affect the focal intensity.The intensity decrease is proportional to the squared pulse spectrum width and the squared total distortions of the second and third gratings of the four-grating compressor and the total distortions of two gratings of the two-grating compressor.
基金supported by the National Research Foundation grant funded by the Korean government(No,2023R1A2C2007190,RS-2024-00398068)partially funded by the Natural Science Foundation of Shandong Province,China(No.ZR2022QE206).
文摘The effects of solid solution on the deformation behavior of binary Mg-xZn(x=0,1,2 wt%)alloys featuring a designated texture that enables extension twinning under tension parallel to the basal pole in most grains,were investigated using in-situ neutron diffraction and the EVPSC-TDT model.Neutron diffraction was used to quantitatively track grain-level lattice strains and diffraction intensity changes(related to mechanical twinning)in differently oriented grains of each alloy during cyclic tensile/compressive loadings.These measurements were accurately captured by the model.The stress-strain curves of Mg-1 wt%Zn and Mg-2 wt%Zn alloys show as-expected solid solution strengthening from the addition of Zn compared to pure Mg.The macroscopic yielding and hardening behaviors are explained by alternating slip and twinning modes as calculated by the model.The solid solution's influence on individual deformation modes,including basal〈a〉slip,prismatic〈a〉slip,and extension twinning,was then quantitatively assessed in terms of activity,yielding behavior,and hardening response by combining neutron diffraction results with crystal plasticity predictions.The Mg-1 wt%Zn alloy displays distinct yielding and hardening behavior due to solid solution softening of prismatic〈a〉slip.Additionally,the dependence of extension twinning,in terms of the twinning volume fraction,on Zn content exhibits opposite trends under tensile and compressive loadings.
基金supported by the State Grid Corporation Science and Technology Project(No.5419-202158503A-0-5-ZN)。
文摘The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.
基金supported by the National Key Research and Development Program of China (2022YFB4602600)National Natural Science Foundation of China (Grant Nos. 52425508 & 52221001)the Hunan Provincial Natural Science Foundation of China (2025JJ60286)。
文摘Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.
基金supported by the Australian Research Council Linkage Project(No.LP200200717)co sponsored by Newmont Corporation(United States)and Vega Industries(India)+1 种基金the Powder Diffraction Beamline at the Australia’s Nuclear Science and Technology Organisation(No.PDR19870),Australiathe Centre for Microscopy and Microanalysis at the University of Queensland(No.1366),Australia。
文摘Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.
