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
A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during t...A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during twin-roll casting.When soaked in 3.5 wt.%NaCl solution,Al_(2)Ca shell with a low electrochemical potential prevents direct contact of noble Al_(8)Mn_(4)Y with Mg matrix,mitigating the micro-galvanic corrosion and meanwhile accelerating the formation of uniform corrosion film.Thereafter,solute(Al,Ca)-segregation motivates the formation of heterogeneous multilayered corrosion product films,enhancing corrosion resistance and even achieving self-healing upon long-term corrosion.Notably,the dilute Mg alloy exhibits a corrosion rate as low as 0.22±0.05 mm·y^(−1).展开更多
The relations between the non-equilibrium segregation process of P and the change of the texture in Fe-P alloys have been studied by analytical electron microscope and orientation distribution function.It was shown th...The relations between the non-equilibrium segregation process of P and the change of the texture in Fe-P alloys have been studied by analytical electron microscope and orientation distribution function.It was shown that P segregated preferentialy on the{110}slip planes, the P segregation structures with repeating cycle a=1.582 nm form at 450℃.<001>// ND direction abated.<111>//ND direction heightened.And{111}<110>has a tendancy to transform into{111}<143>texture in recovering process.{111}<143>direction trans- forms into{111}<112>direction after recrystalizing.A model to describe the effects of non-equilibrium segregation structures of P on orientation change was proposed and em- ployed to interpret the experiment results.展开更多
The effect of Cr/Mn segregation on the abnormal banded structure of high carbon bearing steel was studied by reheating and hot rolling.With the use of an optical microscope, scanning electron microscope, transmission ...The effect of Cr/Mn segregation on the abnormal banded structure of high carbon bearing steel was studied by reheating and hot rolling.With the use of an optical microscope, scanning electron microscope, transmission electron microscope, and electron probe microanalyzer, the segregation characteristics of alloying elements in cast billet and their relationship with hot-rolled plate banded structure were revealed.The formation causes of an abnormal banded structure and the elimination methods were analyzed.Results indicate the serious positive segregation of C, Cr, and Mn alloy elements in the billet.Even distribution of Cr/Mn elements could not be achieved after 10 h of heat preservation at 1200℃, and the spacing of the element aggregation area increased, but the segregation index of alloy elements decreased.Obvious alloying element segregation characteristics are present in the banded structure of the hot-rolled plate.This distinct white band is composed of martensitic phases.The formation of this abnormal pearlite–martensite banded structure is due to the interaction between the undercooled austenite transformation behavior of hot-rolled metal and the segregation of its alloying elements.Under the air cooling after rolling, controlling the segregation index of alloy elements can reduce or eliminate the abnormal banded structure.展开更多
Al2O3/A356-La alloy composites were fabricated by squeeze casting, and the effects of La on the solidified structure and the solute segregation during alloy solidification were studied. The results indicate that the s...Al2O3/A356-La alloy composites were fabricated by squeeze casting, and the effects of La on the solidified structure and the solute segregation during alloy solidification were studied. The results indicate that the structure of the matrix alloy becomes fine and small by the addition of La. La has been richened at the interface to help improve the wettability between the fiber and Al alloy, but there are no intermetallic compounds richening La found at the interface yet. There is no special influence of La on the Mg segregation in the matrix alloy. The distribution of Mg and La in the composites has been at the same position--near the interface.展开更多
The effect of mold electromagnetic stirring(M-EMS)on the solidification structure and solute segregation in the continuous casting bloom of U78CrV steel is investigated.The solute distribution in the macroscale is ana...The effect of mold electromagnetic stirring(M-EMS)on the solidification structure and solute segregation in the continuous casting bloom of U78CrV steel is investigated.The solute distribution in the macroscale is analyzed using a carbon–sulfur analyzer and that in the microscale is measured with an electron probe microanalyzer.The Image-J software is applied to analyze the number density and area ratio of segregation spots.The results show that the segregation spots are mainly located in the columnar to equiaxed transition zone and the equiaxed zone,which are enriched with C,Cr,and Mn elements.With the M-EMS applied,the columnar grain inclines to the upstream side.As the current intensity increases,the deflecting angle of columnar grain rises,especially with the current intensity larger than 300 A.Besides,the center segregation shows a declining trend and the area fraction of the equiaxed zone rises clearly.Moreover,it is found that the area ratio and number density of segregation spots increase with the higher current intensity of M-EMS.展开更多
The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that th...The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field.For the Al-Cu and Ni-Mn-Ga alloys,the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10μm/s and 5μm/s.Further,the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated.Numerical results reveal that the rotary thermoelectric(TE)magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field.This flow will induce the formation of the ring-like macro-segregation and structure.Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results.Therefore,the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.展开更多
Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,an...Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,and microsegregation of the Inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and investigated.The results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM process.Moreover,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm spacing.Furthermore,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR process.The average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.展开更多
Single-phase Al-Mg alloys processed by severe plastic deformation(SPD)usually suffer from unsatisfactory thermal stability at moderate to high temperatures with recrystallization occurring and obvious grain coarsening...Single-phase Al-Mg alloys processed by severe plastic deformation(SPD)usually suffer from unsatisfactory thermal stability at moderate to high temperatures with recrystallization occurring and obvious grain coarsening.In the present work,an Al-7Mg alloy prepared by equal-channel angular pressing(ECAP)possessed markedly enhanced thermal stability upon annealing at moderate to high temperatures(200-275℃),compared with those ultrafine-grained dilute Al-Mg alloys with a uniform microstructure.The enhanced thermal stability is due primarily to the multimodal grain structure consisting of nano-,ultrafine-and micron-sized grains,strong segregation and/or clusters of Mg solute along grain boundaries(GBs),and Al_(3)Mg_(2)precipitates formed during annealing.First,extensive recovery predominates over recrystallization and consumes most of the stored energy in the ECAPed Al-7Mg alloy annealed at≤275℃,leading to the recrystallization and growth of nano/ultrafine grains being retarded or postponed.Moreover,Mg solute segregation and/or clusters along GBs of nano/ultrafine grains could further suppress grain growth via diminishing GB energy and dragging GBs efficiently.In addition,Al_(3)Mg_(2)precipitates formed with increasing annealing time could inhibit grain growth by pinning GBs.The present multimodal-grained Al-7Mg alloy with enhanced thermal stability is believed to be particularly attractive in potential engineering applications at moderate to high temperatures.展开更多
By calculating the electron structures of the phases that phosphor, sulfur and alloying elements dissolving inγ-Fe, the reason why alloying elements can bring centerline segregation in continuous casting slab (CCS) w...By calculating the electron structures of the phases that phosphor, sulfur and alloying elements dissolving inγ-Fe, the reason why alloying elements can bring centerline segregation in continuous casting slab (CCS) with nA, the number of electrons on the strongest covalent bonds, and the structure formation factor S were investigated, and an electron structural criterion to control and to eliminate the centerline segregation was advanced. Basing on this, the electron structures of a part of rare earth phosphides and sulfides are calculated, the physical mechanism that rare earth elements can control the segregation of phosphor and sulfur is analyzed, and the criterion is well verified.展开更多
Near-αtitanium alloy and Ti_(2)AlNb alloy powders premixed with different proportions were prepared on the near-αtitanium alloy substrate by laser deposition technique,and the microstructure characteristics were ana...Near-αtitanium alloy and Ti_(2)AlNb alloy powders premixed with different proportions were prepared on the near-αtitanium alloy substrate by laser deposition technique,and the microstructure characteristics were analyzed and discussed.Results show that numerous river-like sub-grain structures are formed inside the equiaxed B2 grains of the laser-deposited premixed titanium alloy powders with the proportion of Ti_(2)AlNb above 40wt%,whereas the needle-like structure within coarse columnarβgrains exist with the proportion of Ti_(2)AlNb below 40wt%.It is noteworthy that the decrease in laser power and scanning speed can accelerate the formation of sub-grain structures.Based on the analysis of experimental results,it can be inferred that the formation of sub-grain structure not only is related to the precipitation of O phase due to composition micro-segregation at sub-grain boundaries,but also is inseparable from the stacking faults caused by the internal stress during the laser deposition.展开更多
Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometrie...Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometries,and harsh environments.In this work,oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni-Cu-P functionalization of(Fe_(0.76)Si_(0.09)B_(0.1)P_(0.05))_(99)Nb_(1)amorphous powder precursors and then thermal spraying them onto aluminum(Al)substrate.Benefiting from the unique magnetic-electric structure,the coating@Al composite delivered prominent EMI shielding performance.The EMI shielding effectiveness(SE)of modified coating@Al composite is~41 dB at 8-12 GHz,doubling the value of Al substrate and is 15 dB greater than that of Ni-Cu-P-free coating@Al composite.Microstructure analysis showed that the introduced Ni−Cu−P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic matrix.Electron holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu−P conductive network,magnetic loss from Fe-based amorphous coating,and the electromagnetic interactions in the oriented segregated architectures.Moreover,the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading environments.Our work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms.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
Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically...Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.展开更多
"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic s..."Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.展开更多
Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution...Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution.Tantalum(Ta)additions enhance the stability of the γ′phase but introduce processing challenges,including pronounced solidification segregation,the formation of secondary phases,and increased susceptibility to cracking during processing.The influence of Ta content on elemental segregation,solidification microstructure,phase precipitation kinetics,and hot deformation behaviour in GH4151 was systematically investigated.Processing windows derived from the dynamic materials model(DMM)and microstructural evolution under varying thermomechanical conditions are further examined.Key findings reveal the severe Ta segregation(segregation coefficient K≈1.608);Ta promotes γ/γ′eutectic and η phase formation,increasing γ′phase volume fraction from 54% to approximately 63%;and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window;optimized thermomechanical processing parameters(elevated temperatures and strain rates)enhance recrystallization kinetics and hot workability,thereby mitigating cracking propensity.展开更多
Copolymers with super segregated structure of hydrophilic methoxy poly（ethylene glycol） （mPEG） and fluorophilic poly（1H,1H,2H,2H-perfluorodecyl acrylate） （PFA） were prepared. And just because of this super seg...Copolymers with super segregated structure of hydrophilic methoxy poly（ethylene glycol） （mPEG） and fluorophilic poly（1H,1H,2H,2H-perfluorodecyl acrylate） （PFA） were prepared. And just because of this super segregated structure which was resulted from the extremely strong incompatibility between the two blocks, several interesting self- assembly behaviors of the copolymers were displayed and studied under different conditions. Transmission electron microscope （TEM） showed that with the increase of PFA in the polymerization system, the incompatibility in this super segregated structure became stronger, and the self-assembly behavior changed from ball-like or rod-like to vesicles, and finally collapsed to sheet-like. The self-assembly behavior changed likewise when the initial concentration increased. And the interesting formation of these barrel-like and spindle-like vesicles was finally studied with different cooling speeds. It＇s finally found that with this super segregation structure, these new self-assembly morphology might be formed due to the extremely strong incompatibility between mPEG and PFA segments.展开更多
Elastomeric vitrimers with covalent adaptable networks are promising candidates to overcome the intrinsic drawbacks of conventional covalently-crosslinked elastomers;however, most elastomeric vitrimers show poor mecha...Elastomeric vitrimers with covalent adaptable networks are promising candidates to overcome the intrinsic drawbacks of conventional covalently-crosslinked elastomers;however, most elastomeric vitrimers show poor mechanical properties and require the addition of exogenous catalysts. Herein, we fabricate a catalyst-free and mechanically robust elastomeric vitrimer by constructing a segregated structure of sodium alginate (SA) in the continuous matrix of epoxidized natural rubber (ENR), and further crosslinking the composite by exchangeable hydroxyl ester bonds at the ENR-SA interfaces. The manufacturing process of the elastomeric vitrimer is facile and environmentally friendly without hazardous solvents or exogenous catalysts, as the abundant hydroxyl groups of the segregated SA phase can act as catalyst to activate the crosslinking reaction and promote the dynamic transesterification reaction. Interestingly, the segregated SA structure bears most of the load owing to its high modulus and small deformability, and thus ruptures preferentially upon deformation, leading to efficient energy dissipation.Moreover, the periodic stiffness fluctuation between rigid segregated SA phase and soft ENR matrix is beneficial to the crack-resisting. As a result,the elastomeric vitrimer manifests exceptional combination of catalyst-free, defect-tolerance, high tensile strength and toughness. In addition,the elastomeric vitrimer also exhibits multi-shape memory behavior which may further broaden its applications.展开更多
Directional solidification experiments on Pb-Bi peritectic alloys were carried out at very low growth rate （v=0.5 μm/s） and high temperature gradient （G=35 K/mm） in an improved Bridgman furnace. The banding struc...Directional solidification experiments on Pb-Bi peritectic alloys were carried out at very low growth rate （v=0.5 μm/s） and high temperature gradient （G=35 K/mm） in an improved Bridgman furnace. The banding structures were observed in both hypoperitectic and hyperperitectic compositions （Pb-xBi, x=26%, 28%, 30% and 34%）. Tree-like primary α phase in the center of the sample surrounded by the peritectic β phase matrix was also observed, resulting from the melt convection. The banding microstructure, however, is found to be transient after the tree-like structure and only the peritectic phase forms after a few bands. Composition variations in the banding structure are measured to determine the nucleation undercooling for both α and β phases. In a finite length sample, convection is shown to lead only to the transient formation of bands. In this transient banding regime, only a few bands with a variable width are formed, and this transient banding process can occur over a wide range of compositions inside the two-phase peritectic region.展开更多
An electromagnetic interference （EMI） shielding composite based on ultrahigh molecular weight polyethylene （UHMWPE） loaded with economical graphite-carbon black （CB） hybrid fillers was prepared via a green and f...An electromagnetic interference （EMI） shielding composite based on ultrahigh molecular weight polyethylene （UHMWPE） loaded with economical graphite-carbon black （CB） hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% （15 wt%） yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers （e.g., carbon nanotubes and graphene nanosheets） based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB （1/3, W/W） hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in tuna provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.展开更多
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 National Natural Science Foundation of China under Grant Nos.52234009 and 52274383Partial financial support came from the Fundamental Research Funds for the Central Universities,JLU,Program for JLU Science and Technology Innovative Research Team(JLUSTIRT,2017TD-09)Program for the Central University Youth Innovation Team.
文摘A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during twin-roll casting.When soaked in 3.5 wt.%NaCl solution,Al_(2)Ca shell with a low electrochemical potential prevents direct contact of noble Al_(8)Mn_(4)Y with Mg matrix,mitigating the micro-galvanic corrosion and meanwhile accelerating the formation of uniform corrosion film.Thereafter,solute(Al,Ca)-segregation motivates the formation of heterogeneous multilayered corrosion product films,enhancing corrosion resistance and even achieving self-healing upon long-term corrosion.Notably,the dilute Mg alloy exhibits a corrosion rate as low as 0.22±0.05 mm·y^(−1).
文摘The relations between the non-equilibrium segregation process of P and the change of the texture in Fe-P alloys have been studied by analytical electron microscope and orientation distribution function.It was shown that P segregated preferentialy on the{110}slip planes, the P segregation structures with repeating cycle a=1.582 nm form at 450℃.<001>// ND direction abated.<111>//ND direction heightened.And{111}<110>has a tendancy to transform into{111}<143>texture in recovering process.{111}<143>direction trans- forms into{111}<112>direction after recrystalizing.A model to describe the effects of non-equilibrium segregation structures of P on orientation change was proposed and em- ployed to interpret the experiment results.
文摘The effect of Cr/Mn segregation on the abnormal banded structure of high carbon bearing steel was studied by reheating and hot rolling.With the use of an optical microscope, scanning electron microscope, transmission electron microscope, and electron probe microanalyzer, the segregation characteristics of alloying elements in cast billet and their relationship with hot-rolled plate banded structure were revealed.The formation causes of an abnormal banded structure and the elimination methods were analyzed.Results indicate the serious positive segregation of C, Cr, and Mn alloy elements in the billet.Even distribution of Cr/Mn elements could not be achieved after 10 h of heat preservation at 1200℃, and the spacing of the element aggregation area increased, but the segregation index of alloy elements decreased.Obvious alloying element segregation characteristics are present in the banded structure of the hot-rolled plate.This distinct white band is composed of martensitic phases.The formation of this abnormal pearlite–martensite banded structure is due to the interaction between the undercooled austenite transformation behavior of hot-rolled metal and the segregation of its alloying elements.Under the air cooling after rolling, controlling the segregation index of alloy elements can reduce or eliminate the abnormal banded structure.
基金This work was financially supported by the Chinese Ministry of Education (No. 00191) and the Natural Science Founda-tion of Jiangxi Province, China (No. 0150032)
文摘Al2O3/A356-La alloy composites were fabricated by squeeze casting, and the effects of La on the solidified structure and the solute segregation during alloy solidification were studied. The results indicate that the structure of the matrix alloy becomes fine and small by the addition of La. La has been richened at the interface to help improve the wettability between the fiber and Al alloy, but there are no intermetallic compounds richening La found at the interface yet. There is no special influence of La on the Mg segregation in the matrix alloy. The distribution of Mg and La in the composites has been at the same position--near the interface.
基金the support from the High Steel Center(HSC),S&T Program of Hebei(No.20311006D)National Natural Science Foundation of China(No.51904024)the Fundamental Research Funds for Central Universities(No.FRF-TP-18-098A1).
文摘The effect of mold electromagnetic stirring(M-EMS)on the solidification structure and solute segregation in the continuous casting bloom of U78CrV steel is investigated.The solute distribution in the macroscale is analyzed using a carbon–sulfur analyzer and that in the microscale is measured with an electron probe microanalyzer.The Image-J software is applied to analyze the number density and area ratio of segregation spots.The results show that the segregation spots are mainly located in the columnar to equiaxed transition zone and the equiaxed zone,which are enriched with C,Cr,and Mn elements.With the M-EMS applied,the columnar grain inclines to the upstream side.As the current intensity increases,the deflecting angle of columnar grain rises,especially with the current intensity larger than 300 A.Besides,the center segregation shows a declining trend and the area fraction of the equiaxed zone rises clearly.Moreover,it is found that the area ratio and number density of segregation spots increase with the higher current intensity of M-EMS.
基金the financial supports from National foundation of Science(Nos.51690164 and 51805321)Shanghai Science and Technology Committee Grant(Nos.19XD1401600 and 19010500300)
文摘The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field.For the Al-Cu and Ni-Mn-Ga alloys,the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10μm/s and 5μm/s.Further,the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated.Numerical results reveal that the rotary thermoelectric(TE)magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field.This flow will induce the formation of the ring-like macro-segregation and structure.Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results.Therefore,the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.
基金supported by the National Natural Science Foundation of China(Grant Nos.51674070,51874085,and U1435205)Also,this project was supported by the Transformation Project of Major Scientific and Technological Achievements in Shenyang(Grant No.Z17-5-003)and the"Innovation&Entrepreneurship Talents"Introduction Plan of Jiangsu Province in 2018.
文摘Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,and microsegregation of the Inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and investigated.The results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM process.Moreover,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm spacing.Furthermore,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR process.The average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.
基金financially supported by the National Natural Science Foundation of China(Nos.51922048,51790483 and 51871108)the Changjiang Scholars Program(No.T2017035)。
文摘Single-phase Al-Mg alloys processed by severe plastic deformation(SPD)usually suffer from unsatisfactory thermal stability at moderate to high temperatures with recrystallization occurring and obvious grain coarsening.In the present work,an Al-7Mg alloy prepared by equal-channel angular pressing(ECAP)possessed markedly enhanced thermal stability upon annealing at moderate to high temperatures(200-275℃),compared with those ultrafine-grained dilute Al-Mg alloys with a uniform microstructure.The enhanced thermal stability is due primarily to the multimodal grain structure consisting of nano-,ultrafine-and micron-sized grains,strong segregation and/or clusters of Mg solute along grain boundaries(GBs),and Al_(3)Mg_(2)precipitates formed during annealing.First,extensive recovery predominates over recrystallization and consumes most of the stored energy in the ECAPed Al-7Mg alloy annealed at≤275℃,leading to the recrystallization and growth of nano/ultrafine grains being retarded or postponed.Moreover,Mg solute segregation and/or clusters along GBs of nano/ultrafine grains could further suppress grain growth via diminishing GB energy and dragging GBs efficiently.In addition,Al_(3)Mg_(2)precipitates formed with increasing annealing time could inhibit grain growth by pinning GBs.The present multimodal-grained Al-7Mg alloy with enhanced thermal stability is believed to be particularly attractive in potential engineering applications at moderate to high temperatures.
基金the Natural Science Foundation of Liaoning under grant No.20022150 the National Natural Science Foundation of China under grant No.50271030.
文摘By calculating the electron structures of the phases that phosphor, sulfur and alloying elements dissolving inγ-Fe, the reason why alloying elements can bring centerline segregation in continuous casting slab (CCS) with nA, the number of electrons on the strongest covalent bonds, and the structure formation factor S were investigated, and an electron structural criterion to control and to eliminate the centerline segregation was advanced. Basing on this, the electron structures of a part of rare earth phosphides and sulfides are calculated, the physical mechanism that rare earth elements can control the segregation of phosphor and sulfur is analyzed, and the criterion is well verified.
基金National Natural Science Foundation of China(51974259)Xi'an Municipal Bureau of Science and Technology(21ZCZZHXJS-QCY6-0008)Industry-Academic Cooperation Project of Aero Engine Corporation of China(HFZL2020CXY021)。
文摘Near-αtitanium alloy and Ti_(2)AlNb alloy powders premixed with different proportions were prepared on the near-αtitanium alloy substrate by laser deposition technique,and the microstructure characteristics were analyzed and discussed.Results show that numerous river-like sub-grain structures are formed inside the equiaxed B2 grains of the laser-deposited premixed titanium alloy powders with the proportion of Ti_(2)AlNb above 40wt%,whereas the needle-like structure within coarse columnarβgrains exist with the proportion of Ti_(2)AlNb below 40wt%.It is noteworthy that the decrease in laser power and scanning speed can accelerate the formation of sub-grain structures.Based on the analysis of experimental results,it can be inferred that the formation of sub-grain structure not only is related to the precipitation of O phase due to composition micro-segregation at sub-grain boundaries,but also is inseparable from the stacking faults caused by the internal stress during the laser deposition.
基金supported by National Key Research and Development Program of China(No.2016YFB0300500)National Natural Science Foundation of China(No.51771215)+1 种基金Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025(No.2018B10084)China Postdoctoral Science Foundation(No.2020M673174)。
文摘Manipulation of the internal architecture is essential for electromagnetic interference(EMI)shielding performance of metal-based coatings,which can address the electromagnetic pollution in large-size,complex geometries,and harsh environments.In this work,oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni-Cu-P functionalization of(Fe_(0.76)Si_(0.09)B_(0.1)P_(0.05))_(99)Nb_(1)amorphous powder precursors and then thermal spraying them onto aluminum(Al)substrate.Benefiting from the unique magnetic-electric structure,the coating@Al composite delivered prominent EMI shielding performance.The EMI shielding effectiveness(SE)of modified coating@Al composite is~41 dB at 8-12 GHz,doubling the value of Al substrate and is 15 dB greater than that of Ni-Cu-P-free coating@Al composite.Microstructure analysis showed that the introduced Ni−Cu−P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic matrix.Electron holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu−P conductive network,magnetic loss from Fe-based amorphous coating,and the electromagnetic interactions in the oriented segregated architectures.Moreover,the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading environments.Our work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms.
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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51271156,11474234,and 61403318)the Natural Science Foundation of Fujian Province of China(Grant Nos.2013J01255 and 2013J06002)
文摘Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.
基金supported by the National Natural Science Foundation of China(NSFC,31970564,32000397,32171982)the Fundamental Research Funds for the Central Universities(2662023PY004)。
文摘"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.
基金supported by the National Science and Technology Major Project(No.J2019-VI-0006-0120)the National Natural Science Foundation of China(No.52074092).
文摘Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution.Tantalum(Ta)additions enhance the stability of the γ′phase but introduce processing challenges,including pronounced solidification segregation,the formation of secondary phases,and increased susceptibility to cracking during processing.The influence of Ta content on elemental segregation,solidification microstructure,phase precipitation kinetics,and hot deformation behaviour in GH4151 was systematically investigated.Processing windows derived from the dynamic materials model(DMM)and microstructural evolution under varying thermomechanical conditions are further examined.Key findings reveal the severe Ta segregation(segregation coefficient K≈1.608);Ta promotes γ/γ′eutectic and η phase formation,increasing γ′phase volume fraction from 54% to approximately 63%;and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window;optimized thermomechanical processing parameters(elevated temperatures and strain rates)enhance recrystallization kinetics and hot workability,thereby mitigating cracking propensity.
基金financially supported by the National Natural Science Foundation of China(Nos.51173185 and 51303179)
文摘Copolymers with super segregated structure of hydrophilic methoxy poly（ethylene glycol） （mPEG） and fluorophilic poly（1H,1H,2H,2H-perfluorodecyl acrylate） （PFA） were prepared. And just because of this super segregated structure which was resulted from the extremely strong incompatibility between the two blocks, several interesting self- assembly behaviors of the copolymers were displayed and studied under different conditions. Transmission electron microscope （TEM） showed that with the increase of PFA in the polymerization system, the incompatibility in this super segregated structure became stronger, and the self-assembly behavior changed from ball-like or rod-like to vesicles, and finally collapsed to sheet-like. The self-assembly behavior changed likewise when the initial concentration increased. And the interesting formation of these barrel-like and spindle-like vesicles was finally studied with different cooling speeds. It＇s finally found that with this super segregation structure, these new self-assembly morphology might be formed due to the extremely strong incompatibility between mPEG and PFA segments.
基金financially supported by the National Natural Science Foundation of China (Nos. 51873110 and 51790501)State Key Laboratory of Polymer Materials Engineering (No. sklpme2019-2-14)the Fundamental Research Funds for Central Universities。
文摘Elastomeric vitrimers with covalent adaptable networks are promising candidates to overcome the intrinsic drawbacks of conventional covalently-crosslinked elastomers;however, most elastomeric vitrimers show poor mechanical properties and require the addition of exogenous catalysts. Herein, we fabricate a catalyst-free and mechanically robust elastomeric vitrimer by constructing a segregated structure of sodium alginate (SA) in the continuous matrix of epoxidized natural rubber (ENR), and further crosslinking the composite by exchangeable hydroxyl ester bonds at the ENR-SA interfaces. The manufacturing process of the elastomeric vitrimer is facile and environmentally friendly without hazardous solvents or exogenous catalysts, as the abundant hydroxyl groups of the segregated SA phase can act as catalyst to activate the crosslinking reaction and promote the dynamic transesterification reaction. Interestingly, the segregated SA structure bears most of the load owing to its high modulus and small deformability, and thus ruptures preferentially upon deformation, leading to efficient energy dissipation.Moreover, the periodic stiffness fluctuation between rigid segregated SA phase and soft ENR matrix is beneficial to the crack-resisting. As a result,the elastomeric vitrimer manifests exceptional combination of catalyst-free, defect-tolerance, high tensile strength and toughness. In addition,the elastomeric vitrimer also exhibits multi-shape memory behavior which may further broaden its applications.
基金Project (20110491492) supported by the China Postdoctoral Science FoundationProject (20114BAB216017) supported by the Natural Science Foundation of Jiangxi Province, ChinaProject (GJJ12035) supported by the Science Foundation of the Educational Department of Jiangxi Province, China
文摘Directional solidification experiments on Pb-Bi peritectic alloys were carried out at very low growth rate （v=0.5 μm/s） and high temperature gradient （G=35 K/mm） in an improved Bridgman furnace. The banding structures were observed in both hypoperitectic and hyperperitectic compositions （Pb-xBi, x=26%, 28%, 30% and 34%）. Tree-like primary α phase in the center of the sample surrounded by the peritectic β phase matrix was also observed, resulting from the melt convection. The banding microstructure, however, is found to be transient after the tree-like structure and only the peritectic phase forms after a few bands. Composition variations in the banding structure are measured to determine the nucleation undercooling for both α and β phases. In a finite length sample, convection is shown to lead only to the transient formation of bands. In this transient banding regime, only a few bands with a variable width are formed, and this transient banding process can occur over a wide range of compositions inside the two-phase peritectic region.
基金financially supported by the National Natural Science Foundation of China(Nos.51421061,51120135002 and 51473102)the Innovation Team Program of Science and Technology Department of Sichuan Province(No.2014TD0002)the China Postdoctoral Science Foundation(Nos.2015M572474 and 2016T90848)
文摘An electromagnetic interference （EMI） shielding composite based on ultrahigh molecular weight polyethylene （UHMWPE） loaded with economical graphite-carbon black （CB） hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% （15 wt%） yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers （e.g., carbon nanotubes and graphene nanosheets） based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB （1/3, W/W） hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in tuna provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.
