The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are o...The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.展开更多
The pure iron was melted and deoxidized by metallic Al and rare earth elements La, Ce and Y respectively at 1600℃ in a vertical resistance furnace. The morphology, chemical composition and size distribution of the in...The pure iron was melted and deoxidized by metallic Al and rare earth elements La, Ce and Y respectively at 1600℃ in a vertical resistance furnace. The morphology, chemical composition and size distribution of the inclusions in deoxidized liquid iron have been investigated by using of SEM and image-analysis techniques. The investigated results show that the deoxidation products in molten iron are complex inclusions of rare earth oxide or A12O3 combined with FeO finely distributed. The proper holding time and rapid cooling rate can make inclusions finer. La, Y and Al are more effective than Ce for obtaining finely distributed inclusions.展开更多
The robust exponential stabilization problem for uncertain systems isstudied. Based on the solution for a nominal linear quadratic regulator problem with a prescribeddegree of stability, the methods of constructing st...The robust exponential stabilization problem for uncertain systems isstudied. Based on the solution for a nominal linear quadratic regulator problem with a prescribeddegree of stability, the methods of constructing state feedback controllers are developed to ensurethe robust stability of the closed loop system under the conditions weaker than the matchingcondition. Also, the cases where the matching condition is satisfied are considered in detail. Someexamples are included to show the solution methods.展开更多
The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the def...The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.展开更多
The skin friction and heat transfer occurring in the laminar boundary layerwhich caused by a vertical liquid jet impinging on a continuously moving horizontal plate werestudied. Similarity solutions for shear stress a...The skin friction and heat transfer occurring in the laminar boundary layerwhich caused by a vertical liquid jet impinging on a continuously moving horizontal plate werestudied. Similarity solutions for shear stress and heat distribution were obtained by using thehooting technique. The results show that the skin friction decreases with an increase of velocityparameter, the evolving of thermal boundary decrease with increasing in Prandtl number, but increasewith increasing of velocity parameter.展开更多
A mathematical model with cytotoxic cells of hepatitis B virus (HBV)infection is set up based on a basic model of virus dynamics without cytotoxic cells andexperimental observation of anti-viral drag therapy for HBV i...A mathematical model with cytotoxic cells of hepatitis B virus (HBV)infection is set up based on a basic model of virus dynamics without cytotoxic cells andexperimental observation of anti-viral drag therapy for HBV infection patients. A quantitativeanalysis of dynamic behaviors shows that the model has three kinds of equilibrium points, whichrepresent the patient's complete recovery without immune ability, complete recovery with immuneability, and HBV persistent infection at the end of the treatment with drag lamivudine,respectively. Our model may provide possible quantitative interpretations for the treatments ofchronic HBV infections with the drag lamivudine, in particularly explain why the plasma virus ofNowak et al. 's patients turnover the original level after stopping the lamivudine treatment.展开更多
The transport behavior of free boundary value problems for a class ofgeneralized diffusion equations was studied. Suitable similarity transformations were used toconvert the problems into a class of singular nonlinear...The transport behavior of free boundary value problems for a class ofgeneralized diffusion equations was studied. Suitable similarity transformations were used toconvert the problems into a class of singular nonlinear two-point boundary value problems andsimilarity solutions were numerical presented for different representations of heat conductionfunction, convection function, heat flux function, and power law parameters by utilizing theshooting technique. The results revealed the flux transfer mechanism and the character as well asthe effects of parameters on the solutions.展开更多
A suitable similarity transformation is introduced to reduce the laminarboundary layer equations of power law fluids to a class of singular nonlinear two-point boundaryvalue problems. The kin friction and shear stress...A suitable similarity transformation is introduced to reduce the laminarboundary layer equations of power law fluids to a class of singular nonlinear two-point boundaryvalue problems. The kin friction and shear stress distributions for boundary layer flow over amoving flat plate are investigated by utilizing the shooting technique. Results indicate that foreach fixed value of the power law exponent n or the velocity ratio parameter xi, the skin frictionand shear stress decrease with the increasing of n or xi respectively.展开更多
A new sol-gel process for the preparation of ultrafine nickel hydroxideelectrode materials was developed. The composite electrodes consisting of carbon nanotubes andNi(OH)_2 were developed by mixing the hydroxide and ...A new sol-gel process for the preparation of ultrafine nickel hydroxideelectrode materials was developed. The composite electrodes consisting of carbon nanotubes andNi(OH)_2 were developed by mixing the hydroxide and carbon nanotubes together in different massratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layercapacitor was considered and its electrochemical properties were characterized by cyclic voltammetryand dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with anoperating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors wereobserved with much higher specific capacitance values of 24 F/g compared with that of EDLC (12 F/g)by introducing 60 percent Ni(0H)_2 in the anode material. By using the modified anode of aNi(OH)_2/carbon nanotubes composite electrode, the specific capacitance of the cell was lesssensitive to discharge current density compared with that of the capacitor employing pure nickelhydroxide as anode. The combined capacitor in this study exhibits high energy density and stablepower characteristics.展开更多
A mathematical model, surface-particle-emulsion heat transfer model, ispresented by considering voidage variance in emulsion in the vicinity of an immersed surface. Heattransfer near the surface is treated by disperse...A mathematical model, surface-particle-emulsion heat transfer model, ispresented by considering voidage variance in emulsion in the vicinity of an immersed surface. Heattransfer near the surface is treated by dispersed particles touching the surface and through theemulsion when the distance from the surface is greater than the diameter of a particle. A film withan adjustable thickness which separates particles from the surface is not introduced in this model.The coverage ratio of particles on the surface is calculated by a stochastic model of particlepacking density on a surface. By comparison of theoretical solutions with experimental data fromsome references, the mathematical model shows better qualitative and quantitative prediction forlocal heat transfer coefficients around a horizontal immersed tube in a fluidized bed.展开更多
The problem of momentum and heat transfer in a compressible boundary layerbehind a thin expansion wave was solved by the application of the similarity transformation and theshooting technique. Utilizing the analytical...The problem of momentum and heat transfer in a compressible boundary layerbehind a thin expansion wave was solved by the application of the similarity transformation and theshooting technique. Utilizing the analytical expression of a two-point boundary value problem formomentum transfer, the energy boundary layer solution was represented as a function of thedimensionless velocity, and as the parameters of the Prandtl number, the velocity ratio, and thetemperature ratio.展开更多
The thermodynamic factor in diffusion in the L1_2-type non-stoichiometricintermetallic compounds Ni_3Ga and Pt_3In was derived from the experimentally measured activities ofGa and In, respectively. The results show th...The thermodynamic factor in diffusion in the L1_2-type non-stoichiometricintermetallic compounds Ni_3Ga and Pt_3In was derived from the experimentally measured activities ofGa and In, respectively. The results show that the thermodynamic factor in diffusion in the Ni_3Gaand Pt_3In compounds exhibits the maximum near the stoichiometric composition with the variation ofcomposition over the compound region. The values indicate strong interaction between Ni and Gaatoms, as well as Pt and In atoms, respectively, as expected in ordered alloys.展开更多
Based on pair potential, the Bragg Williams (B-W) model is modified to takeinto account the effect of the lattice parameter on theoretical order-disorder transformationanalysis. The main purpose of this work is to und...Based on pair potential, the Bragg Williams (B-W) model is modified to takeinto account the effect of the lattice parameter on theoretical order-disorder transformationanalysis. The main purpose of this work is to understand the basic aspects of this effect andrelated reasonable model on order-disorder transformation. In the present approach, theconfiguration free energy is chosen as function of the lattice parameter and the long-range order.This energy is calculated through Taylor's expansion, starting from the disordered state. It wasfound that the configuration free energy has been strongly modified when the lattice parameter istaken into account. It was also found only one type of order-disorder transformation exists in ABalloy and three kinds of order-disorder transformations for non-equiatomic alloy system such as A_3Balloy. This result is in agreement with experiments.展开更多
The growth of (100} oriented CVD (Chemical Vapor Deposition) diamond film under Joe-Badgwell-Hauge (J-B-H) model is simulated at atomic scale by using revised KMC (Kinetic Monte Carlo) method. The results show that: (...The growth of (100} oriented CVD (Chemical Vapor Deposition) diamond film under Joe-Badgwell-Hauge (J-B-H) model is simulated at atomic scale by using revised KMC (Kinetic Monte Carlo) method. The results show that: (1) under Joe's model, the growth mechanism from single carbon species is suitable for the growth of (100) oriented CVD diamond film in low temperature; (2) the deposition rate and surface roughness (Rq) under Joe's model are influenced intensively by temperature (Ta) and not evident bymass fraction W of atom chlorine; (3)the surface roughness increases with the deposition rate, i.e. the film quality becomes worse with elevated temperature, in agreement with Grujicic's prediction; (4) the simulation results cannot make sure the role of single carbon insertion.展开更多
A second order heat equation with convection in an infinite medium isstudied. Suitable similarity transformations are used to reduce the parabolic heat equation to aClass of singular nonlinear boundary value problems....A second order heat equation with convection in an infinite medium isstudied. Suitable similarity transformations are used to reduce the parabolic heat equation to aClass of singular nonlinear boundary value problems. Numerical solutions are presented for differentrepresehtations of heat conduction, heat convection, heat flux, and power law parameters byutilizing the shooting technique. The results reveal the heat transfer characteristic and the effectof parameters on the solutions.展开更多
A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series f...A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solid-liquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.展开更多
Temperature distribution and control have been investigated in a liquefiedpetroleum gas (LPG) fluidized bed with hollow corundum spheres (A1_2O_3) of 0.867-1.212 mm indiameter at moderately high temperatures (800-1100...Temperature distribution and control have been investigated in a liquefiedpetroleum gas (LPG) fluidized bed with hollow corundum spheres (A1_2O_3) of 0.867-1.212 mm indiameter at moderately high temperatures (800-1100℃). Experiments were carried out for the airconsumption coefficient α in the range of 0.3 to 1.0 and the fluidization number N in the range of1.3 to 3.0. Particle properties, initial bed height, α and N all affect temperature distribution inthe bed. Bed temperature can be adjusted about 200℃ by combined the adjusting of α and N.展开更多
An aerosol process for making aluminum nitride nano-powder by decompositionof single compound diethylalumimm az-ide was described. X-ray diffraction (XRD) and transmissionelectron microscopy (TEM) were used to study c...An aerosol process for making aluminum nitride nano-powder by decompositionof single compound diethylalumimm az-ide was described. X-ray diffraction (XRD) and transmissionelectron microscopy (TEM) were used to study characters of the A1N powder. It is shown that theprocess can produce spherical A1N powder with mean particle diameters ranging from 10 to 50 nm at500-800°C. The generated amorphous A1N powder is characterized by a BET (Brunauer-Emmett-Teller)surface area of 103 m2/g and is very reactive to moisture.展开更多
The dynamic process of non-equilibrium grain boundary segregation of traceboron in Fe-40 percent Ni alloy during cooling and the effect of cooling rate were investigated byboron tracking autoradiography technique. The...The dynamic process of non-equilibrium grain boundary segregation of traceboron in Fe-40 percent Ni alloy during cooling and the effect of cooling rate were investigated byboron tracking autoradiography technique. The results indicate that during cooling process, theamount of segregated boron on grain boundary firstly increases fast, then enters a comparativelyeven increasing stage and increases rapidly again at the third stage. The details of each stagevaried with cooling rate are explained. When the segregation develops to a certain degree, thesegregated boron atoms transform from solute status to precipitate status.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No.10272003, No. 10032010, and No. 10372004) the Talent Foundation of the University of Sciences and Technology Beijing.
文摘The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.
文摘The pure iron was melted and deoxidized by metallic Al and rare earth elements La, Ce and Y respectively at 1600℃ in a vertical resistance furnace. The morphology, chemical composition and size distribution of the inclusions in deoxidized liquid iron have been investigated by using of SEM and image-analysis techniques. The investigated results show that the deoxidation products in molten iron are complex inclusions of rare earth oxide or A12O3 combined with FeO finely distributed. The proper holding time and rapid cooling rate can make inclusions finer. La, Y and Al are more effective than Ce for obtaining finely distributed inclusions.
基金This work was financially supported by the National Science Foundation of China(No.19971088).
文摘The robust exponential stabilization problem for uncertain systems isstudied. Based on the solution for a nominal linear quadratic regulator problem with a prescribeddegree of stability, the methods of constructing state feedback controllers are developed to ensurethe robust stability of the closed loop system under the conditions weaker than the matchingcondition. Also, the cases where the matching condition is satisfied are considered in detail. Someexamples are included to show the solution methods.
基金[This work was financially supported by a research grant from the Hong Kong Polytechnic University (No.G-V694).]
文摘The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.
基金[This work was financially supported by "973" key foundation of China (No.G 1998061510).]
文摘The skin friction and heat transfer occurring in the laminar boundary layerwhich caused by a vertical liquid jet impinging on a continuously moving horizontal plate werestudied. Similarity solutions for shear stress and heat distribution were obtained by using thehooting technique. The results show that the skin friction decreases with an increase of velocityparameter, the evolving of thermal boundary decrease with increasing in Prandtl number, but increasewith increasing of velocity parameter.
文摘A mathematical model with cytotoxic cells of hepatitis B virus (HBV)infection is set up based on a basic model of virus dynamics without cytotoxic cells andexperimental observation of anti-viral drag therapy for HBV infection patients. A quantitativeanalysis of dynamic behaviors shows that the model has three kinds of equilibrium points, whichrepresent the patient's complete recovery without immune ability, complete recovery with immuneability, and HBV persistent infection at the end of the treatment with drag lamivudine,respectively. Our model may provide possible quantitative interpretations for the treatments ofchronic HBV infections with the drag lamivudine, in particularly explain why the plasma virus ofNowak et al. 's patients turnover the original level after stopping the lamivudine treatment.
基金This work was financially supported by the Cross-Century Talents Projects of Educational Ministry of China and the 973 Key Item (No. G1998061510).]
文摘The transport behavior of free boundary value problems for a class ofgeneralized diffusion equations was studied. Suitable similarity transformations were used toconvert the problems into a class of singular nonlinear two-point boundary value problems andsimilarity solutions were numerical presented for different representations of heat conductionfunction, convection function, heat flux function, and power law parameters by utilizing theshooting technique. The results revealed the flux transfer mechanism and the character as well asthe effects of parameters on the solutions.
基金This work was financially supported by the Cross-Century Talents Projects of Educational Ministry, China and the "973" Key Item(
文摘A suitable similarity transformation is introduced to reduce the laminarboundary layer equations of power law fluids to a class of singular nonlinear two-point boundaryvalue problems. The kin friction and shear stress distributions for boundary layer flow over amoving flat plate are investigated by utilizing the shooting technique. Results indicate that foreach fixed value of the power law exponent n or the velocity ratio parameter xi, the skin frictionand shear stress decrease with the increasing of n or xi respectively.
文摘A new sol-gel process for the preparation of ultrafine nickel hydroxideelectrode materials was developed. The composite electrodes consisting of carbon nanotubes andNi(OH)_2 were developed by mixing the hydroxide and carbon nanotubes together in different massratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layercapacitor was considered and its electrochemical properties were characterized by cyclic voltammetryand dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with anoperating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors wereobserved with much higher specific capacitance values of 24 F/g compared with that of EDLC (12 F/g)by introducing 60 percent Ni(0H)_2 in the anode material. By using the modified anode of aNi(OH)_2/carbon nanotubes composite electrode, the specific capacitance of the cell was lesssensitive to discharge current density compared with that of the capacitor employing pure nickelhydroxide as anode. The combined capacitor in this study exhibits high energy density and stablepower characteristics.
基金This work was financially supported by the Education Ministry of China
文摘A mathematical model, surface-particle-emulsion heat transfer model, ispresented by considering voidage variance in emulsion in the vicinity of an immersed surface. Heattransfer near the surface is treated by dispersed particles touching the surface and through theemulsion when the distance from the surface is greater than the diameter of a particle. A film withan adjustable thickness which separates particles from the surface is not introduced in this model.The coverage ratio of particles on the surface is calculated by a stochastic model of particlepacking density on a surface. By comparison of theoretical solutions with experimental data fromsome references, the mathematical model shows better qualitative and quantitative prediction forlocal heat transfer coefficients around a horizontal immersed tube in a fluidized bed.
基金This work was supported by the "Cross-Century Talents Projects of the Educational Ministry of China"the "Projects of Investigations of Post Graduate School, University of Science and Technology Beijing".
文摘The problem of momentum and heat transfer in a compressible boundary layerbehind a thin expansion wave was solved by the application of the similarity transformation and theshooting technique. Utilizing the analytical expression of a two-point boundary value problem formomentum transfer, the energy boundary layer solution was represented as a function of thedimensionless velocity, and as the parameters of the Prandtl number, the velocity ratio, and thetemperature ratio.
基金This project is jointly supported by the National Natural Science Foundation of China (No. 29871005) the Science Foundation of Austria (No. P12962-CHE).
文摘The thermodynamic factor in diffusion in the L1_2-type non-stoichiometricintermetallic compounds Ni_3Ga and Pt_3In was derived from the experimentally measured activities ofGa and In, respectively. The results show that the thermodynamic factor in diffusion in the Ni_3Gaand Pt_3In compounds exhibits the maximum near the stoichiometric composition with the variation ofcomposition over the compound region. The values indicate strong interaction between Ni and Gaatoms, as well as Pt and In atoms, respectively, as expected in ordered alloys.
基金This work was financially supported by the National Natural Science Foundation of China under contract No. 59895151-01.
文摘Based on pair potential, the Bragg Williams (B-W) model is modified to takeinto account the effect of the lattice parameter on theoretical order-disorder transformationanalysis. The main purpose of this work is to understand the basic aspects of this effect andrelated reasonable model on order-disorder transformation. In the present approach, theconfiguration free energy is chosen as function of the lattice parameter and the long-range order.This energy is calculated through Taylor's expansion, starting from the disordered state. It wasfound that the configuration free energy has been strongly modified when the lattice parameter istaken into account. It was also found only one type of order-disorder transformation exists in ABalloy and three kinds of order-disorder transformations for non-equiatomic alloy system such as A_3Balloy. This result is in agreement with experiments.
基金[This work was financially supported by National Natural Science Founds of China (No. 59872003).]
文摘The growth of (100} oriented CVD (Chemical Vapor Deposition) diamond film under Joe-Badgwell-Hauge (J-B-H) model is simulated at atomic scale by using revised KMC (Kinetic Monte Carlo) method. The results show that: (1) under Joe's model, the growth mechanism from single carbon species is suitable for the growth of (100) oriented CVD diamond film in low temperature; (2) the deposition rate and surface roughness (Rq) under Joe's model are influenced intensively by temperature (Ta) and not evident bymass fraction W of atom chlorine; (3)the surface roughness increases with the deposition rate, i.e. the film quality becomes worse with elevated temperature, in agreement with Grujicic's prediction; (4) the simulation results cannot make sure the role of single carbon insertion.
基金This work was supported by Cross-Century Talents Projects of Educational Ministry of China the "973" Key Foundation under the contract No.G1998061510.]
文摘A second order heat equation with convection in an infinite medium isstudied. Suitable similarity transformations are used to reduce the parabolic heat equation to aClass of singular nonlinear boundary value problems. Numerical solutions are presented for differentrepresehtations of heat conduction, heat convection, heat flux, and power law parameters byutilizing the shooting technique. The results reveal the heat transfer characteristic and the effectof parameters on the solutions.
基金This work was financially supported by the Major State Basic Research Development Program of China (No. G2000067206_1).
文摘A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solid-liquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.
基金This work was financially suppoded by the Key Project Foundation for Science and Technology Research by the Education Ministry of China (No.00020).
文摘Temperature distribution and control have been investigated in a liquefiedpetroleum gas (LPG) fluidized bed with hollow corundum spheres (A1_2O_3) of 0.867-1.212 mm indiameter at moderately high temperatures (800-1100℃). Experiments were carried out for the airconsumption coefficient α in the range of 0.3 to 1.0 and the fluidization number N in the range of1.3 to 3.0. Particle properties, initial bed height, α and N all affect temperature distribution inthe bed. Bed temperature can be adjusted about 200℃ by combined the adjusting of α and N.
文摘An aerosol process for making aluminum nitride nano-powder by decompositionof single compound diethylalumimm az-ide was described. X-ray diffraction (XRD) and transmissionelectron microscopy (TEM) were used to study characters of the A1N powder. It is shown that theprocess can produce spherical A1N powder with mean particle diameters ranging from 10 to 50 nm at500-800°C. The generated amorphous A1N powder is characterized by a BET (Brunauer-Emmett-Teller)surface area of 103 m2/g and is very reactive to moisture.
基金This work was financially supported by the Projects of Development of the State Key Fundamental Research(National 973 Project)(No.G19980601507).]
文摘The dynamic process of non-equilibrium grain boundary segregation of traceboron in Fe-40 percent Ni alloy during cooling and the effect of cooling rate were investigated byboron tracking autoradiography technique. The results indicate that during cooling process, theamount of segregated boron on grain boundary firstly increases fast, then enters a comparativelyeven increasing stage and increases rapidly again at the third stage. The details of each stagevaried with cooling rate are explained. When the segregation develops to a certain degree, thesegregated boron atoms transform from solute status to precipitate status.
