Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ expe...Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ experiments and on completely degraded samples,which restrict the assessment on initial and final stage.By combining in situ X-ray diffraction under controlled 85%relative humidity,and live observations of the water-induced degradation using liquid-cell transmission electron microscopy,we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-theart mixed cation/anion(Cs_(0.05)(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17)I_(0.83))_(3)(CsMAFA)into PbI_(2) through a dissolution/recrystallization mechanism and,on the other hand,to a non-equilibrium phase segregation leading to CsPb_(2)Br_(5) and a Cesium-poor/iodide-rich Cs_(0.05)-x(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17-2y)I_(0.83)+2y)_(3) perovskite.This degradation mechanism is corroborated at atomic-scale resolution through solid-state ^(1)H and ^(133)Cs NMR analysis.Exposure to moisture leads to a film containing important heterogeneities in terms of morphology,photoluminescence intensities,and lifetimes.Our results provide new insights and consensus that complex perovskite compositions,though very performant as champion devices,are comparatively metastable,a trait that limits the chances to achieve long-term stability.展开更多
Proton exchange membranes (PEMs) are a key material for proton exchange membrane fuel cells (PEM-FCs), Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductiv...Proton exchange membranes (PEMs) are a key material for proton exchange membrane fuel cells (PEM-FCs), Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly(ether ether ketone) (SPEEK). By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic(MD) simulations and transmission electron microscope (TEM) observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.展开更多
The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phas...The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phase stability and current hysteresis caused by photo-induced phase segregation in CsPbBr_(2)I represent major obstacles to further improvements in the PCE for such devices.In this review,we describe the basic structure and optical properties of CsPbBr_(2)I,and systematically elaborate on the mechanism of the phase transition.We then discuss the strategies in progress to suppress phase transition in CsPbBr_(2)I,and their potential application in the photovoltaic field.Finally,challenges and application prospects for CsPbBr2I PSCs are summarized in the final section of this article.展开更多
Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits thei...Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits their photovoltaic performance.Here,Pb S quantum dot has been synthesized and demonstrated as seeds for modulation crystallization dynamics of the mixed Pb-Sn inorganic perovskites,allowing an enhanced film quality and significantly suppressing phase segregation.With this additive power conversion efficiency of 8%and 6%is obtained under irradiation of full sunlight in planar and mesoporous structured solar cells in combination with CsPb_(0.5) Sn_(0.5)I_(2)Br inorganic perovskite,respectively.Our finding reveals exploring the actual Pb/Sn atoms location in perovskite structure and its influence on developing efficient and stable low-bandgap perovskite solar cells.展开更多
The microstructures and mechanical properties of Ti Al alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a gr...The microstructures and mechanical properties of Ti Al alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.%) alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45 Al alloy for Liquid→Liquid+β(Ti). The free energies of solid phase and liquid phase for Ti-45 Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45 Al alloy. With the growth of the β(Ti), dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases.展开更多
The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The resu...The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter- faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg on MC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grain boundary segregation element,but also a phase interface segregation one.展开更多
Powder segregation induced by mold filling is an important phenomenon that affects the final quality of metal injection molding (MIM). The prediction of segregation in MIM requires a bi-phase flow model to describe ...Powder segregation induced by mold filling is an important phenomenon that affects the final quality of metal injection molding (MIM). The prediction of segregation in MIM requires a bi-phase flow model to describe distinctly the flows of metallic powder and polymer binder. Viscous behaviors for the flows of each phase should hence be determined. The coefficient of interaction between the flows of two phases should also be evaluated. However, only viscosity of the mixed feedstock is measurable by capillary tests. Wall sticking is supposed in the traditional model for capillary tests, while the wall slip is important to be taken into account in MIM injection. Objective of the present paper is to introduce the slip effect in bi-phase simulation, and search the suitable way to determine the viscous behaviors for each phase with the consideration of wall slip in capillary tests. Analytical and numerical methods were proposed to realize such a specific purpose. The proposed method is based on the mass conservation between the capillary flows in mono-phase model for the mixed feedstock and in bi-phase model for the flows of two phases. Examples of the bi-phase simulation in MIM were realized with the software developed by research team. The results show evident segregation, which is valuable for improving the mould designs.展开更多
Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instabilit...Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instability,wherein the homogeneous film is likely to segregate into multi-phases during the fabrication and ageing process,thus resulting in the efficiency reduction of perovskite solar cells(PSCs)devices.This review focuses on the cation induced phase segregation,and elucidates the segregation mechanisms from the perspectives of film formation and ageing process,respectively.Furthermore,the influence of cation segregation on device performance and operational stability are discussed.And based on these understandings,viable strategies are proposed for the design of phase-stable mixed composition halide perovskites and for suppressing segregation to benefit its development towards commercial applications.展开更多
The aim of the present study was to investigate the effect of element segregation on the microstructure and γ′ phase in a γ/γ′ cobalt-based superalloy. Several samples were prepared from a cast alloy and homogeni...The aim of the present study was to investigate the effect of element segregation on the microstructure and γ′ phase in a γ/γ′ cobalt-based superalloy. Several samples were prepared from a cast alloy and homogenized at 1300°C for different times, with a maximum of 24 h. A microstructural study of the cast alloy using wavelength-dispersive spectroscopic analysis revealed that elements such as Al, Ti, and Ni segregated mostly within interdendritic regions, whereas W atoms were segregated within dendrite cores. With an increase in homogenization time, segregation decreased and the initial dendritic structure was eliminated. Field-emission scanning electron microscopy micrographs showed that the γ′ phases in the cores and interdendritic regions of the as-cast alloy were 392 and 124 nm, respectively. The size difference of γ′ was found to be due to the different segregation behaviors of constituent elements during solidification. After homogenization, particularly after 16 h, segregation decreased; thus, the size, chemical composition, and hardness of the precipitated γ′ phase was mostly uniform throughout the samples.展开更多
The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with ...The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with the sputtering time increasing. The as-sputtered films are super saturation solid solution of Cu-Fe. After annealing at 500℃, α-Fe particle can be segregated from the Cu matrix. The orientations α-Fe particles in the annealed film without magnetic field are random. But the clear texture of α-Fe particles in the annealed film with magnetic field is formed, and the 〈001〉 direction of α-Fe particles tends to be parallel to the magnetic field direction.展开更多
ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understo...ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understood.In this work,ZYTO TBCs were prepared by air plasma spraying(APS)and their thermal cycling performances were investigated at 1150℃.Despite of the good bulk properties,APS ZYTO TBCs present an extremely short thermal fatigue life.This is attributed to the non-equilibrium grain-boundary segregation of TaO_(2.5) induced by limited solubility and rapid quenching during APS process,resulting in a tetragonal(t)to cubic(c)and metastable-tetragonal(tm)phase transformation in ZYTO TBCs.The volume shrinkage(~0.74vol%)of phase transformation leads to many cracks at the c/tm phase boundaries after deposition.On the other hand,the formation of cubic phase with massive grain-boundary Ta segregation induces a large intergranular embrittlement and a weak bonding strength(~5.3 MPa),resulting in the premature failure of the ZYTO TBCs.展开更多
On the basis of a multi-length scale modeling, a mixture-averaged multi-component /multiphase micro-segregation model was proposed without pre-set function for the micro-scale solute profile. The model explains the ef...On the basis of a multi-length scale modeling, a mixture-averaged multi-component /multiphase micro-segregation model was proposed without pre-set function for the micro-scale solute profile. The model explains the effect of morphologies of solidifying phases and solid back diffusion (SBD) on segregation, and covers the two limiting solidification cases of Scheil and Lever-rule models. A commercial Thermo-Calc software package/database was linked to the algorithms via its TQ6-interface for instantaneous determination of the related thermodynamic data of the multi-component alloys. The influences of cooling rate and other parameters on the solidification path and micro-segregation behavior were numerically investigated by sample calculation of the ternary Al-Cu-Mg alloys. A parallel experimental investigation on Al-Cu-Si alloys solidified under different cooling conditions was conducted to validate the theoretical model. Reasonable agreements were gained between the predicted solidification paths and the measured results.展开更多
基金financial support from Region Hauts-de-France,FEDER,and Electricité de France(EDF)through PEROVSTAB programfinancial support from the IR-RMN-THC FR-3050 CNRS France for conducting solid-state NMR measurements.P.R.and G.N.M.R+1 种基金financial support from University of Lille and région Hauts-de-France.F.S“IMPRESSIVE”project which received funding from the European Union’s Horizon 2020 Research and Innovation Program under grant agreement number 826013.
文摘Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ experiments and on completely degraded samples,which restrict the assessment on initial and final stage.By combining in situ X-ray diffraction under controlled 85%relative humidity,and live observations of the water-induced degradation using liquid-cell transmission electron microscopy,we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-theart mixed cation/anion(Cs_(0.05)(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17)I_(0.83))_(3)(CsMAFA)into PbI_(2) through a dissolution/recrystallization mechanism and,on the other hand,to a non-equilibrium phase segregation leading to CsPb_(2)Br_(5) and a Cesium-poor/iodide-rich Cs_(0.05)-x(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17-2y)I_(0.83)+2y)_(3) perovskite.This degradation mechanism is corroborated at atomic-scale resolution through solid-state ^(1)H and ^(133)Cs NMR analysis.Exposure to moisture leads to a film containing important heterogeneities in terms of morphology,photoluminescence intensities,and lifetimes.Our results provide new insights and consensus that complex perovskite compositions,though very performant as champion devices,are comparatively metastable,a trait that limits the chances to achieve long-term stability.
基金financially supported by the National Key Research and Development Program of China (2016YFB0101203)the National Natural Science Foundation of China (91545205,21633008)
文摘Proton exchange membranes (PEMs) are a key material for proton exchange membrane fuel cells (PEM-FCs), Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly(ether ether ketone) (SPEEK). By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic(MD) simulations and transmission electron microscope (TEM) observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.
基金the National Natural Science Foundation of China(52073131,51902148,61704099,61874166,U1832149,51801088 and 51802024)the Natural Science Foundation of Gansu Province(20JR5RA227,20JR5RA217,20JR5RA278)the Fundamental Research Funds for the Central Universities(lzujbky-2020-61,lzujbky-2019-88 and lzujbky-2020-kb06).
文摘The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phase stability and current hysteresis caused by photo-induced phase segregation in CsPbBr_(2)I represent major obstacles to further improvements in the PCE for such devices.In this review,we describe the basic structure and optical properties of CsPbBr_(2)I,and systematically elaborate on the mechanism of the phase transition.We then discuss the strategies in progress to suppress phase transition in CsPbBr_(2)I,and their potential application in the photovoltaic field.Finally,challenges and application prospects for CsPbBr2I PSCs are summarized in the final section of this article.
基金Financial support from the National Key Research and Development Program of China (2019YFE0101300, 2018YFB1502900)the National Natural Science Foundation of China (No. 21975088)+1 种基金the National Natural Science Foundation of China Major International (Regional) Joint Research Project (No. 51961165106)the double first-class research funding of China-EU Institute for Clean and Renewable Energy (3011187029)。
文摘Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits their photovoltaic performance.Here,Pb S quantum dot has been synthesized and demonstrated as seeds for modulation crystallization dynamics of the mixed Pb-Sn inorganic perovskites,allowing an enhanced film quality and significantly suppressing phase segregation.With this additive power conversion efficiency of 8%and 6%is obtained under irradiation of full sunlight in planar and mesoporous structured solar cells in combination with CsPb_(0.5) Sn_(0.5)I_(2)Br inorganic perovskite,respectively.Our finding reveals exploring the actual Pb/Sn atoms location in perovskite structure and its influence on developing efficient and stable low-bandgap perovskite solar cells.
文摘The microstructures and mechanical properties of Ti Al alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.%) alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45 Al alloy for Liquid→Liquid+β(Ti). The free energies of solid phase and liquid phase for Ti-45 Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45 Al alloy. With the growth of the β(Ti), dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases.
文摘The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter- faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg on MC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grain boundary segregation element,but also a phase interface segregation one.
基金Specialized Research Fund for the Doc-toral Program of Higher Education (No.20020613005)
文摘Powder segregation induced by mold filling is an important phenomenon that affects the final quality of metal injection molding (MIM). The prediction of segregation in MIM requires a bi-phase flow model to describe distinctly the flows of metallic powder and polymer binder. Viscous behaviors for the flows of each phase should hence be determined. The coefficient of interaction between the flows of two phases should also be evaluated. However, only viscosity of the mixed feedstock is measurable by capillary tests. Wall sticking is supposed in the traditional model for capillary tests, while the wall slip is important to be taken into account in MIM injection. Objective of the present paper is to introduce the slip effect in bi-phase simulation, and search the suitable way to determine the viscous behaviors for each phase with the consideration of wall slip in capillary tests. Analytical and numerical methods were proposed to realize such a specific purpose. The proposed method is based on the mass conservation between the capillary flows in mono-phase model for the mixed feedstock and in bi-phase model for the flows of two phases. Examples of the bi-phase simulation in MIM were realized with the software developed by research team. The results show evident segregation, which is valuable for improving the mould designs.
基金National Natural Science Foundation of China(22109057,21805010,21975028,52172182,22011540377,22005035)Beijing Municipal Science and Technology Project(Z181100005118002)+2 种基金Beijing Municipal Natural Science Foundation(JQ19008)the China Postdoctoral Science Foundation(Grant No.2020TQ0043,2020M680012)Research Foundation of Jiangxi Educational Committee(GJJ200836).
文摘Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instability,wherein the homogeneous film is likely to segregate into multi-phases during the fabrication and ageing process,thus resulting in the efficiency reduction of perovskite solar cells(PSCs)devices.This review focuses on the cation induced phase segregation,and elucidates the segregation mechanisms from the perspectives of film formation and ageing process,respectively.Furthermore,the influence of cation segregation on device performance and operational stability are discussed.And based on these understandings,viable strategies are proposed for the design of phase-stable mixed composition halide perovskites and for suppressing segregation to benefit its development towards commercial applications.
文摘The aim of the present study was to investigate the effect of element segregation on the microstructure and γ′ phase in a γ/γ′ cobalt-based superalloy. Several samples were prepared from a cast alloy and homogenized at 1300°C for different times, with a maximum of 24 h. A microstructural study of the cast alloy using wavelength-dispersive spectroscopic analysis revealed that elements such as Al, Ti, and Ni segregated mostly within interdendritic regions, whereas W atoms were segregated within dendrite cores. With an increase in homogenization time, segregation decreased and the initial dendritic structure was eliminated. Field-emission scanning electron microscopy micrographs showed that the γ′ phases in the cores and interdendritic regions of the as-cast alloy were 392 and 124 nm, respectively. The size difference of γ′ was found to be due to the different segregation behaviors of constituent elements during solidification. After homogenization, particularly after 16 h, segregation decreased; thus, the size, chemical composition, and hardness of the precipitated γ′ phase was mostly uniform throughout the samples.
基金Financial supports from The National Natural Science Foundation of China(Nos.51625402,51790483,51801069 and U19A2084)are greatly acknowledgedPartial financial support came from The Science and Technology Devel-opment Program of Jilin Province(Nos.20190901010JC,20190103003JH,20200401025GX and 20200201002JC)The Changjiang Scholars Program(T2017035).
文摘The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with the sputtering time increasing. The as-sputtered films are super saturation solid solution of Cu-Fe. After annealing at 500℃, α-Fe particle can be segregated from the Cu matrix. The orientations α-Fe particles in the annealed film without magnetic field are random. But the clear texture of α-Fe particles in the annealed film with magnetic field is formed, and the 〈001〉 direction of α-Fe particles tends to be parallel to the magnetic field direction.
基金financially supported by the National Natural Science Foundation of China (Nos. 51971139 and 51875341)the National Science and Technology Major Project of China (No. 2017-VI-0011-0083)
文摘ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understood.In this work,ZYTO TBCs were prepared by air plasma spraying(APS)and their thermal cycling performances were investigated at 1150℃.Despite of the good bulk properties,APS ZYTO TBCs present an extremely short thermal fatigue life.This is attributed to the non-equilibrium grain-boundary segregation of TaO_(2.5) induced by limited solubility and rapid quenching during APS process,resulting in a tetragonal(t)to cubic(c)and metastable-tetragonal(tm)phase transformation in ZYTO TBCs.The volume shrinkage(~0.74vol%)of phase transformation leads to many cracks at the c/tm phase boundaries after deposition.On the other hand,the formation of cubic phase with massive grain-boundary Ta segregation induces a large intergranular embrittlement and a weak bonding strength(~5.3 MPa),resulting in the premature failure of the ZYTO TBCs.
基金supported by the Open Project of State Key Laboratory of Powder Metallurgy of Central South University (Grant No. 2008112042)the National Natural Science Foundation of China (Grant Nos. 51071062 and 50801019)Project 973 (Grant No. 2011CB610406)
文摘On the basis of a multi-length scale modeling, a mixture-averaged multi-component /multiphase micro-segregation model was proposed without pre-set function for the micro-scale solute profile. The model explains the effect of morphologies of solidifying phases and solid back diffusion (SBD) on segregation, and covers the two limiting solidification cases of Scheil and Lever-rule models. A commercial Thermo-Calc software package/database was linked to the algorithms via its TQ6-interface for instantaneous determination of the related thermodynamic data of the multi-component alloys. The influences of cooling rate and other parameters on the solidification path and micro-segregation behavior were numerically investigated by sample calculation of the ternary Al-Cu-Mg alloys. A parallel experimental investigation on Al-Cu-Si alloys solidified under different cooling conditions was conducted to validate the theoretical model. Reasonable agreements were gained between the predicted solidification paths and the measured results.
基金Supported by the State Key Development Program for Basic Research of China (2009CB623404)Program for New Century Excellent Talents in University,the Programme of Introducing Talents of Discipline to Universities (B06006)State KeyLaboratory for Modification of Chemical Fibers and Polymer Materials (Dong Hua University)
基金supported by the National Natural Science Foundation of China under grant No. 50601002the Scientific Research Foundation for the Returned Over-seas Chinese Scholars, State Education Ministry