We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-or...We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.展开更多
Atomistic simulations were adopted to study the solute segregation effect on dislocation transmutation across the{1012}twin boundaries in magnesium.For pure magnesium,the dislocation-twin reaction resulted in the form...Atomistic simulations were adopted to study the solute segregation effect on dislocation transmutation across the{1012}twin boundaries in magnesium.For pure magnesium,the dislocation-twin reaction resulted in the formation of sessile dislocations accompanied by the fast migration of the twin boundary,and no〈c+a〉dislocation occurred.With Al segregation,instead,two basal dislocations transmuted into one prismatic〈c+a〉dislocation in the twin.Twin migration was significantly impeded,and the resultant twin disconnections stayed localized and had a higher step character than in pure Mg.To reveal the mechanism of the effect of solute segregation,the Peierls barriers of twin disconnections were calculated,and the dynamic evolutions of twin disconnection dipoles were simulated.The results suggested that Al segregation softened the Peierls barrier of twin disconnections but imposed a high pinning force on twin disconnections,thus attenuating their mobility.Moreover,given the same Al segregation,the twin disconnection dipole with a higher step showed greater stability,which explained the presence of localized twin disconnections with a higher step in the cases with Al segregation than in pure magnesium.The solute segregation induced low mobility of twin disconnections contributed to the occurrence of〈c+a〉dislocations.展开更多
The frequency of aneuploid gamete formation increases with maternal age,yet the effects of genetic variants on meiotic chromosome segregation accuracy during aging remain poorly understood.Using the multicellular orga...The frequency of aneuploid gamete formation increases with maternal age,yet the effects of genetic variants on meiotic chromosome segregation accuracy during aging remain poorly understood.Using the multicellular organism Caenorhabditis elegans,we investigate the impact of mutations in the conserved cohesin complex on age-associated meiotic errors.Point mutations in the head domain of the cohesin component SMC-1,which alter local hydrophobicity,cause meiotic defects that vary with age.A severe mutation causes incomplete synapsis and defective crossover formation,and a minor one causes age-related diakinesis bivalent abnormalities.Notably,while the mild mutation causes defects only in aged worms,worms with the severe mutation exhibit significantly alleviated phenotypes with age.Genetic and cytological analyses suggest that this alleviation results from a slowed meiotic progression during early prophase,which restores impaired cohesin loading.These findings reveal that cohesin variants,meiotic progression speed during early prophase,and the overall duration of meiosis collectively shape the accuracy of meiotic chromosome segregation.展开更多
The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC c...The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC carbides and eutectic(γ+γ′)formation,differential thermal analysis(DTA)was utilized to investigate the effect of cooing rate(10-90℃·min^(-1))on solidification behavior and micro-segregation of GH4975 alloy.According to the thermodynamic calculation and distribution characteristics of precipitates,the MC carbides can act as nucleation sites forγdendrites,but the nucleation ofγdendrites becomes less dependent on the MC carbide primers at higher cooling rates.As theγdendrites grow,the elements including Ti and Nb gradually accumulate in the residual liquid and leads to the formation of more MC carbides near the interdendritic region.Finally,the solidification is terminated with the formation of eutectic(γ+γ′).With an increase in cooling rate,the liquidus temperature rises,but the solidus temperature decreases,and thus the solidification range is obviously enlarged.The dendritic structure is significantly refined by the increase of cooling rate.The secondary dendrite arm spacing,λ_(2),as a function of cooling rate,T,can be expressed asλ_(2)=216.78T^(-0.42).Moreover,the increasing cooling rate weakens the back diffusion of Al,Ti,and Nb,increases the undercooling,and limits the growth of precipitates.Consequently,the sizes of MC carbides,eutectic(γ+γ′),and primaryγ′significantly decrease,but the area fraction of eutectic(γ+γ′)linerly increases as the cooling rate rises.Thus moderate cooling rate(such as 30℃·min^(-1))should be selected during the solidification process of GH4975 alloy.展开更多
The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed us...The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed using the metallographic microscope,scanning electron microscope,electron probe microanalyzer,electronic universal testing machine and impact testing machine.The effect of element segregation band after hot rolling on the anisotropy of microstructure and mechanical properties of subsequent heat treatment was investigated.The results show that the essence of improving the banded structure by oxide metallurgy technology in the hot rolling process is to promote the formation of intragranular ferrite to break the bainite band,but the element segregation band produced during hot rolling will be inherited to the subsequent heat treatment process.After Q+T heat treatment,the microstructure is mainly martensite,and there is no obvious banded structure.The shear transformation of martensite weakens the influence of alloying element segregation and avoids the directionality of microstructure and the anisotropy of mechanical properties.After Q+IQ+T heat treatment,the martensite/ferrite bands or continuous martensite bands appear in the microstructure,and with the increase in intercritical quenching temperature,continuous martensite bands become more obvious.The appearance of banded structure aggravates the difference of mechanical properties in all directions,especially the difference of plasticity and toughness in longitudinal and transverse directions.Therefore,the banded structure can be avoided by regulating the nucleation rate difference between the element enrichment and depleted zones during the heat treatment process.The alloying elements segregation is a necessary condition for the formation of banded structure after heat treatment,but it is not a sufficient condition.展开更多
Based on the microscopic phase-field model, ordered domain interfaces formed between D022 （Ni3V） phases along [001] direction in Ni75AlxV25-x alloys were simulated, and the effects of atomic structure on the migrati...Based on the microscopic phase-field model, ordered domain interfaces formed between D022 （Ni3V） phases along [001] direction in Ni75AlxV25-x alloys were simulated, and the effects of atomic structure on the migration characteristic and solute segregation of interfaces were studied. It is found that the migration ability is related to the atomic structure of interfaces, and three kinds of interfaces can migrate except the interface （001）//（002） which has the characteristic of L12 （Ni3Al） structure. V atoms jump to the nearest neighbor site and substitute for Ni, and vice versa. Because of the site selectivity behaviors of jumping atoms, the number of jumping atoms during the migration is the least and the jumping distance of atoms is the shortest among all possible modes, and the atomic structures of interfaces are unchanged before and after the migration. The preferences and degree of segregation or depletion of alloy elements are also related to the atomic structure of interface.展开更多
Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymme...Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.展开更多
Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been...Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been widely studied as an active cathode but still suffer from serious detrimental segregations.To enhance the cathode stability,a PBCC derived A-site medium-entropy Pr_(0.6)La_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Ba_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(ME-PBCC)oxide was prepared and its segregation behaviors were investigated under different conditions.Compared with initial PBCC oxide,the segregations of BaO and Co_(3)O_(4)on the surface of ME-PBCC material are significantly suppressed,especially for Co_(3)O_(4),which is attributed to its higher configuration entropy.Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material,enabling it as a promising cathode for SOFCs.展开更多
Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated...Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.展开更多
This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo sim...This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.展开更多
First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results dem...First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results demonstrate that both P and Mg are segregated at GB,and P has a stronger segregation potency.Mg prefers to substitute at grain boundary plane with the largest absorbable vacancy,whereas P inclines to substitute at the sites near Fe atoms to form strong covalent Fe-P bonds.When Mg exists at GB,the segregation behavior of P may be greatly inhibited by the decrease in possible solution sites and the increase in segregation energy.P has stronger interactions with Mg at GB,forming a lower energy hybridization peak.These results can be used to explain why the addition of a small amount of Mg can ameliorate the temper embrittlement phenomenon.展开更多
Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb al...Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
Upon ageing of a deformed metal,compositional segregation to dislocations and stacking faults is well known to elevate strength.However,Suzuki segregation effects typically result in a modest strength in-crease on the...Upon ageing of a deformed metal,compositional segregation to dislocations and stacking faults is well known to elevate strength.However,Suzuki segregation effects typically result in a modest strength in-crease on the order of 10 MPa for many substitutional face-centered-cubic solid solutions.Severe pre-deformation can lead to significant hardening but often at the cost of substantial tensile ductility af-ter subsequent aging.Here we propose a novel strategy to improve the Suzuki hardening effect in a single-phase CoCrNi alloy by meticulously controlling repetitive straining and annealing conditions with-out compromising ductility.Our findings revealed that multiple stages of annealing along the way of pre-straining significantly increase the fraction of dislocations that trap partitioning species(i.e.Cr),far exceeding the levels achievable through single-shot annealing after straight pre-deformation to the same accumulative strain(40%).Thermodynamically,the segregation of Cr into stacking faults is driven by re-duced local stacking fault energy(SEF)and system energy.The decreased SFE inhibits dislocation cross-slip,promotes partial dislocation nucleation,and facilitates dislocation intersection,leading to a high den-sity of extended stacking fault ribbons in the multi-pass strained and annealed samples.As a result,the yield strength increments of multi-pass treated samples(75±10 MPa)are four times higher than those of single-pass treated samples(18±8 MPa),while retaining an adequate strain hardening rate,thus pre-serving tensile ductility despite of plastic flow at higher stresses.Our strategy shows promise for broader applications,particularly in scenarios where conventional thermomechanical treatments fail to yield sat-isfactory results.展开更多
Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this ...Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this work,we develop a quantitative model to compute the grain boundary segregation energy(ΔE_(seg))in binary Mg based alloys that takes the relative atomic density of GB into account.The model is utilized to computeΔE_(seg)of Al,Zn,Ca,Sn,Y,Gd,and Nd solutes in Mg.The result suggests that rare earth elements and Ca are more prone to GBS than Al,Zn,and Sn.Segregation of Gd solutes can explain the smaller grain size and slower grain growth in Mg-Gd extruded alloys than Mg-Al and Mg-Zn counterparts.It also provides an explanation for the weak extrusion texture in Mg-Gd.展开更多
In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followe...In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.展开更多
Correction to:J.Iron Steel Res.Int.(2025)32:144-158 https://doi.org/10.1007/s42243-024-01416-x The publication of this article unfortunately contained mistakes.Only one corresponding author was named instead of three....Correction to:J.Iron Steel Res.Int.(2025)32:144-158 https://doi.org/10.1007/s42243-024-01416-x The publication of this article unfortunately contained mistakes.Only one corresponding author was named instead of three.The corrected corresponding authors are given below.展开更多
As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding ...As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding on how Y addition affects the microstructural evolution and mechanical properties,the Y segregation behavior at grain boundaries was investigated in Mg-1wt.%Y and Mg-7wt.%Y alloys at different conditions.The segregation intensity and its dependence on the grain boundary misorientation angle were experimentally characterized and computationally predicted.Strong segregation at grain boundaries was observed in both low and high Y-containing alloys.Y segregation was found to remain in alloy Mg-7Y after high-temperature annealing heat treatment at 540℃.No direct correlation between the Y segregation intensity and the grain boundary misorientation angle could be established based on either the experimental characterization or the atomistic simulation with a spectral model.We thus conclude that grain boundary segregation of Y is independent of grain boundary misorientation angle.展开更多
The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation ener...The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.展开更多
In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then hea...In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.展开更多
基金This work used Expanse systems at UCSD through an allocation[PHY240089]from the Advanced Cyberinfrastructure Coordination Ecosystem:Services&Support(ACCESS)programsupported by U.S.National Science Foundation(Grant Nos.2138259,2138286,2138307,2137603 and 2138296).
文摘We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.
基金supported by the National Natural Science Foundation of China(52071039 and 52301156)National Natural Science Foundation of Jiangsu Province of China(BK20241873)Natural Science Foundation of Jiangsu Province(BK20232025 and BK20243005)are greatly acknowledged.
文摘Atomistic simulations were adopted to study the solute segregation effect on dislocation transmutation across the{1012}twin boundaries in magnesium.For pure magnesium,the dislocation-twin reaction resulted in the formation of sessile dislocations accompanied by the fast migration of the twin boundary,and no〈c+a〉dislocation occurred.With Al segregation,instead,two basal dislocations transmuted into one prismatic〈c+a〉dislocation in the twin.Twin migration was significantly impeded,and the resultant twin disconnections stayed localized and had a higher step character than in pure Mg.To reveal the mechanism of the effect of solute segregation,the Peierls barriers of twin disconnections were calculated,and the dynamic evolutions of twin disconnection dipoles were simulated.The results suggested that Al segregation softened the Peierls barrier of twin disconnections but imposed a high pinning force on twin disconnections,thus attenuating their mobility.Moreover,given the same Al segregation,the twin disconnection dipole with a higher step showed greater stability,which explained the presence of localized twin disconnections with a higher step in the cases with Al segregation than in pure magnesium.The solute segregation induced low mobility of twin disconnections contributed to the occurrence of〈c+a〉dislocations.
基金supported by grants from the National Natural Science Foundation of China(32370780 and 32022018)the National Key Research and Development Program of China(2021YFA1101001)+1 种基金the Taishan Scholars Program Special FundSome strains were provided by the CGC,which is funded by NIH Office of Research Infrastructure Programs(P40 OD010440).
文摘The frequency of aneuploid gamete formation increases with maternal age,yet the effects of genetic variants on meiotic chromosome segregation accuracy during aging remain poorly understood.Using the multicellular organism Caenorhabditis elegans,we investigate the impact of mutations in the conserved cohesin complex on age-associated meiotic errors.Point mutations in the head domain of the cohesin component SMC-1,which alter local hydrophobicity,cause meiotic defects that vary with age.A severe mutation causes incomplete synapsis and defective crossover formation,and a minor one causes age-related diakinesis bivalent abnormalities.Notably,while the mild mutation causes defects only in aged worms,worms with the severe mutation exhibit significantly alleviated phenotypes with age.Genetic and cytological analyses suggest that this alleviation results from a slowed meiotic progression during early prophase,which restores impaired cohesin loading.These findings reveal that cohesin variants,meiotic progression speed during early prophase,and the overall duration of meiosis collectively shape the accuracy of meiotic chromosome segregation.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52474362,52174317 and 51904146)the General Project Funded by Liaoning Province Education Department(Grant No.JYTMS20230943)。
文摘The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC carbides and eutectic(γ+γ′)formation,differential thermal analysis(DTA)was utilized to investigate the effect of cooing rate(10-90℃·min^(-1))on solidification behavior and micro-segregation of GH4975 alloy.According to the thermodynamic calculation and distribution characteristics of precipitates,the MC carbides can act as nucleation sites forγdendrites,but the nucleation ofγdendrites becomes less dependent on the MC carbide primers at higher cooling rates.As theγdendrites grow,the elements including Ti and Nb gradually accumulate in the residual liquid and leads to the formation of more MC carbides near the interdendritic region.Finally,the solidification is terminated with the formation of eutectic(γ+γ′).With an increase in cooling rate,the liquidus temperature rises,but the solidus temperature decreases,and thus the solidification range is obviously enlarged.The dendritic structure is significantly refined by the increase of cooling rate.The secondary dendrite arm spacing,λ_(2),as a function of cooling rate,T,can be expressed asλ_(2)=216.78T^(-0.42).Moreover,the increasing cooling rate weakens the back diffusion of Al,Ti,and Nb,increases the undercooling,and limits the growth of precipitates.Consequently,the sizes of MC carbides,eutectic(γ+γ′),and primaryγ′significantly decrease,but the area fraction of eutectic(γ+γ′)linerly increases as the cooling rate rises.Thus moderate cooling rate(such as 30℃·min^(-1))should be selected during the solidification process of GH4975 alloy.
基金supported by the National Natural Science Foundation of China(No.52304358)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230462).
文摘The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed using the metallographic microscope,scanning electron microscope,electron probe microanalyzer,electronic universal testing machine and impact testing machine.The effect of element segregation band after hot rolling on the anisotropy of microstructure and mechanical properties of subsequent heat treatment was investigated.The results show that the essence of improving the banded structure by oxide metallurgy technology in the hot rolling process is to promote the formation of intragranular ferrite to break the bainite band,but the element segregation band produced during hot rolling will be inherited to the subsequent heat treatment process.After Q+T heat treatment,the microstructure is mainly martensite,and there is no obvious banded structure.The shear transformation of martensite weakens the influence of alloying element segregation and avoids the directionality of microstructure and the anisotropy of mechanical properties.After Q+IQ+T heat treatment,the martensite/ferrite bands or continuous martensite bands appear in the microstructure,and with the increase in intercritical quenching temperature,continuous martensite bands become more obvious.The appearance of banded structure aggravates the difference of mechanical properties in all directions,especially the difference of plasticity and toughness in longitudinal and transverse directions.Therefore,the banded structure can be avoided by regulating the nucleation rate difference between the element enrichment and depleted zones during the heat treatment process.The alloying elements segregation is a necessary condition for the formation of banded structure after heat treatment,but it is not a sufficient condition.
基金Projects (50941020, 10902086, 50875217, 20903075) supported by the National Natural Science Foundation of ChinaProjects (SJ08-ZT05, SJ08-B14) supported by the Natural Science Foundation of Shaanxi Province, ChinaProject (CX200905) supported by the Doctorate Foundation of Northwestern Polytechnical University, China
文摘Based on the microscopic phase-field model, ordered domain interfaces formed between D022 （Ni3V） phases along [001] direction in Ni75AlxV25-x alloys were simulated, and the effects of atomic structure on the migration characteristic and solute segregation of interfaces were studied. It is found that the migration ability is related to the atomic structure of interfaces, and three kinds of interfaces can migrate except the interface （001）//（002） which has the characteristic of L12 （Ni3Al） structure. V atoms jump to the nearest neighbor site and substitute for Ni, and vice versa. Because of the site selectivity behaviors of jumping atoms, the number of jumping atoms during the migration is the least and the jumping distance of atoms is the shortest among all possible modes, and the atomic structures of interfaces are unchanged before and after the migration. The preferences and degree of segregation or depletion of alloy elements are also related to the atomic structure of interface.
基金supported by the Scientific and Technological Developing Scheme of Jilin Province under grants no.YDZJ202301ZYTS538the Chinese Academy of Sciences Youth Innovation Promotion Association under grants number 2023234+3 种基金the National Natural Science Foundation of China under grants number U21A20323the Scientific and Technological Developing Scheme of Jilin Province under grants no.SKL202302038the Major Scientific and Technological Projects of Hebei Province under grants No.23291001Zthe Scientific and Technology Project of Hanjiang District.
文摘Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.
基金Project supported by the National Natural Science Foundation of China(22279025,21773048,52302119)the Fundamental Research Funds for the Central Universities(2023FRFK06005,HIT.NSRIF202204)。
文摘Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been widely studied as an active cathode but still suffer from serious detrimental segregations.To enhance the cathode stability,a PBCC derived A-site medium-entropy Pr_(0.6)La_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Ba_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(ME-PBCC)oxide was prepared and its segregation behaviors were investigated under different conditions.Compared with initial PBCC oxide,the segregations of BaO and Co_(3)O_(4)on the surface of ME-PBCC material are significantly suppressed,especially for Co_(3)O_(4),which is attributed to its higher configuration entropy.Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material,enabling it as a promising cathode for SOFCs.
基金support from Interdisciplinary Research Project for Young Teachers of USTB Fundamental Research Funds for the Central Universities(Grant no.FRF-IDRY-23-030).
文摘Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.
基金supported by grants from the National Natural Science Foundation of China(Nos.52031017,51801237)the National Key Laboratory of Science and Technology on High-strength Structural Materials in Central South University,China(No.6142912200106).
文摘This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.
文摘First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results demonstrate that both P and Mg are segregated at GB,and P has a stronger segregation potency.Mg prefers to substitute at grain boundary plane with the largest absorbable vacancy,whereas P inclines to substitute at the sites near Fe atoms to form strong covalent Fe-P bonds.When Mg exists at GB,the segregation behavior of P may be greatly inhibited by the decrease in possible solution sites and the increase in segregation energy.P has stronger interactions with Mg at GB,forming a lower energy hybridization peak.These results can be used to explain why the addition of a small amount of Mg can ameliorate the temper embrittlement phenomenon.
文摘Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
基金sponsored by the National Key Research and Development Program,Major Scientific Instrument Special Pro-gram for Basic Research-Development and Application of All-domestic Three-dimensional Atom Probe Precision Measurement Instrument Project(No.2023YFF0716200)the State Key Lab-oratory of Powder Metallurgy,Central South University,Changsha,China.Q.Cheng was supported by the China Postdoctoral Science Foundation(No.2023M741111,No.GZC20230752)+2 种基金E.Ma acknowl-edges the National Natural Science Foundation of China(Grant No.52231001)J.Ding was supported by the Natural Science Founda-tion of China(Grant No.12004294)the National Youth Talents Program and the HPC platform of Xi’an Jiaotong University.M.W.Chen was supported by the U.S.National Science Foundation grant DMR-1804320.J.H.Chen acknowledges the financial support from the National Natural Science Foundation of China(No.51831004)。
文摘Upon ageing of a deformed metal,compositional segregation to dislocations and stacking faults is well known to elevate strength.However,Suzuki segregation effects typically result in a modest strength in-crease on the order of 10 MPa for many substitutional face-centered-cubic solid solutions.Severe pre-deformation can lead to significant hardening but often at the cost of substantial tensile ductility af-ter subsequent aging.Here we propose a novel strategy to improve the Suzuki hardening effect in a single-phase CoCrNi alloy by meticulously controlling repetitive straining and annealing conditions with-out compromising ductility.Our findings revealed that multiple stages of annealing along the way of pre-straining significantly increase the fraction of dislocations that trap partitioning species(i.e.Cr),far exceeding the levels achievable through single-shot annealing after straight pre-deformation to the same accumulative strain(40%).Thermodynamically,the segregation of Cr into stacking faults is driven by re-duced local stacking fault energy(SEF)and system energy.The decreased SFE inhibits dislocation cross-slip,promotes partial dislocation nucleation,and facilitates dislocation intersection,leading to a high den-sity of extended stacking fault ribbons in the multi-pass strained and annealed samples.As a result,the yield strength increments of multi-pass treated samples(75±10 MPa)are four times higher than those of single-pass treated samples(18±8 MPa),while retaining an adequate strain hardening rate,thus pre-serving tensile ductility despite of plastic flow at higher stresses.Our strategy shows promise for broader applications,particularly in scenarios where conventional thermomechanical treatments fail to yield sat-isfactory results.
基金supported by the National Key Research and Development Program of China(No.2021YFB3702602)the National Natural Science Foundation of China(Nos.51825101,52425101)。
文摘Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this work,we develop a quantitative model to compute the grain boundary segregation energy(ΔE_(seg))in binary Mg based alloys that takes the relative atomic density of GB into account.The model is utilized to computeΔE_(seg)of Al,Zn,Ca,Sn,Y,Gd,and Nd solutes in Mg.The result suggests that rare earth elements and Ca are more prone to GBS than Al,Zn,and Sn.Segregation of Gd solutes can explain the smaller grain size and slower grain growth in Mg-Gd extruded alloys than Mg-Al and Mg-Zn counterparts.It also provides an explanation for the weak extrusion texture in Mg-Gd.
基金Tral Science Foundation of China(Nos.52271103,52334010and 52271031)Partial financial support came from JilinScientific and Technological Development Program(No.20220301026GX)Program for the Central UniversityYouth Innovation Team。
文摘In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.
文摘Correction to:J.Iron Steel Res.Int.(2025)32:144-158 https://doi.org/10.1007/s42243-024-01416-x The publication of this article unfortunately contained mistakes.Only one corresponding author was named instead of three.The corrected corresponding authors are given below.
基金supported by PRISMS(PRedictive Integrated Structural Materials Science)center which is located at University of Michigan and funded by U.S.Department of Energy,Office of Basic Energy Science,Division of Materials Science and Engineering(Grant award number DE-SC0008637)support from Michigan Center for Materials Characterization(MC2)at University of Michigan and Canmet MATERIALS,Natural Resources Canada+1 种基金the Extreme Science and Engineering Discovery Environment(XSEDE)Stampede2 at the TACC through allocation TG-MSS160003the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility operated under Contract No.DE-AC02-05CH11231。
文摘As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding on how Y addition affects the microstructural evolution and mechanical properties,the Y segregation behavior at grain boundaries was investigated in Mg-1wt.%Y and Mg-7wt.%Y alloys at different conditions.The segregation intensity and its dependence on the grain boundary misorientation angle were experimentally characterized and computationally predicted.Strong segregation at grain boundaries was observed in both low and high Y-containing alloys.Y segregation was found to remain in alloy Mg-7Y after high-temperature annealing heat treatment at 540℃.No direct correlation between the Y segregation intensity and the grain boundary misorientation angle could be established based on either the experimental characterization or the atomistic simulation with a spectral model.We thus conclude that grain boundary segregation of Y is independent of grain boundary misorientation angle.
基金support from the National Natural Science Foundation of China(Nos.22173034,11974128,52130101)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No.SKL202206SIC)+2 种基金the Program of Innovative Research Team(in Science and Technology)in University of Jilin Province,the Program for JLU(Jilin University)Science and Technology Innovative Research Team(No.2017TD-09)the Fundamental Research Funds for the Central Universitiesthe computing resources of the High Performance Computing Center of Jilin University,China.
文摘The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.
基金Project supported by the National Natural Science Foundation of China(52301041)Guizhou Provincial Science and Technology Projects(Qingnian No.2024-123)the Special Fund for Special Posts of Guizhou University(2023-26,2023-53)。
文摘In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.
