Metastable liquid phase separation and rapid solidification in a metastable miscibility gap were investigated on the Cu60Co30Cr10 alloy by using the electromagnetic levitation and splat-quenching.It is found that the ...Metastable liquid phase separation and rapid solidification in a metastable miscibility gap were investigated on the Cu60Co30Cr10 alloy by using the electromagnetic levitation and splat-quenching.It is found that the alloy generally has a microstructure consisting of a（Co,Cr）-rich phase embedded in a Cu-rich matrix,and the morphology and size of the（Co,Cr）-rich phase vary drastically with cooling rate.During the electromagnetic levitation solidification processing the cooling rate is lower,resulting in an obvious coalescence tendency of the（Co,Cr）-rich spheroids.The（Co,Cr）-rich phase shows dendrites and coarse spheroids at lower cooling rates.In the splat quenched samples the（Co,Cr）-rich phase spheres were refined significantly and no dendrites were observed.This is probably due to the higher cooling rate,undercooling and interface tension.展开更多
The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was foun...The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two sepa- rated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respec- tively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) drop- lets with the same size.展开更多
（Fe50Co25B15Si10）80Cu20 ribbons are prepared by using the single-roller melt-spinning method. A dual-layer structure consisting of a （Fe, Co）-rich amorphous phase and a Cu-rich crystalline phase forms due to metas...（Fe50Co25B15Si10）80Cu20 ribbons are prepared by using the single-roller melt-spinning method. A dual-layer structure consisting of a （Fe, Co）-rich amorphous phase and a Cu-rich crystalline phase forms due to metastable liquid phase separation before solidification. The magnetic hysteresis loops of the as-quenched and annealed samples are measured at room temperature. It is indicated that the coercivity of the ribbon is almost zero in the as-quenched state. The crystallization leads to the increase of coercivity and decrease of saturation magnetization.展开更多
The bonding of solid steel plate to liquid al uminum was studied using rapid solidification. The relationship models of interf acial shear strength and thickness of interfacial layer of bonding plate vs bond ing para...The bonding of solid steel plate to liquid al uminum was studied using rapid solidification. The relationship models of interf acial shear strength and thickness of interfacial layer of bonding plate vs bond ing parameters (such as preheat temperature of steel plate, temperature of alumi num liquid and bonding time) were respectively established by artificial neural networks perfectly.The bonding parameters for the largest interfacial shear stre ngth were optimized with genetic algorithm successfully. They are 226℃ for preh eating temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8s for bonding time, and the largest interfacial shear strength of bonding pl ate is 71.6 MPa . Under these conditions, the corresponding reasonable thickne ss of interfacial layer (10.8μm) is gotten using the relationship model establi shed by artificial neural networks.展开更多
The bonding of solid steel plate to liquid aluminum was studied using rapidsolidification. The surface of solid steel plate was defatted, descaled, immersed (in K_2ZrF_6 fluxaqueous solution) and stoved. In order to d...The bonding of solid steel plate to liquid aluminum was studied using rapidsolidification. The surface of solid steel plate was defatted, descaled, immersed (in K_2ZrF_6 fluxaqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at theinterface of steel-aluminum solid to liquid bonding under rapid solidification, the interface ofbonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationshipbetween bonding parameters (such as preheat temperature of steel plate, temperature of aluminumliquid and bonding time) and thickness of Fe-Al compound layer at the interface was established byartificial neural networks (ANN) perfectly. The maximum of relative error between the output and thedesired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacialshear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperatureof aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer10.8 μm was got.展开更多
The bonding of solid steel plate to liquid aluminum was studied by using rapid solidification. The relationship between the bonding parameters such as preheat temperature of steel plate, temperature of aluminum liquid...The bonding of solid steel plate to liquid aluminum was studied by using rapid solidification. The relationship between the bonding parameters such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time, and the interfacial shear strength of bonding plate was established by artificial neural networks perfectly. This relationship was optimized with a genetic algorithm. The optimum bonding parameters are: 226 ℃ for preheat temperature of steel plate, 723 ℃ for temperature of aluminum liquid and 15.8 s for bonding time, and the largest interfacial shear strength of bonding plate is 71.6 MPa.展开更多
Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work,rapid solidification of an undercooled liquid Al80.4Cu13.6Si6 ternary eutectic allo...Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work,rapid solidification of an undercooled liquid Al80.4Cu13.6Si6 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The re-lationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K (0.18TE). The undercooled ternary eutectic is composed of α(Al) solid solution,(Si) semiconductor and θ(CuAl2) intermetallic compound. In the (Al+Si+θ) ternary eutectic,(Si) faceted phase grows independently,while (Al) and θ non-faceted phases grow coopera-tively in the lamellar mode. When undercooling is small,only (Al) solid solution forms as the leading phase. Once undercooling exceeds 73 K,(Si) phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary (Al) dendrite,(Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling,while at large undercooling primary (Si) block,(Al+θ) pseudo-binary eutectic and (Al+Si+θ) ternary eutectic coexist. As undercooling increases,the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases.展开更多
The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experim...The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experiments.It is found that a large temperature gradient exists along the vertical direction of melt puddle,whereas there is no obvious temperature variation in the tangent direction of roller surface.After being sprayed from a nozzle,the alloy melt changes the magnitude and di-rection of its flow and velocity rapidly at a height of about 180 μm.The horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-300 μm in height and a momentum boundary layer with 160-240 μm in thickness are formed at the bottom of melt puddle,and the Reynolds number Re is in the range of 870 to 1070 in the boundary layer.With the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases monotonically.The thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases sharply.If Re < 1024,the liquid flow has remarkable effects on the microstructure formation due to dominant momentum transfer.The separated liquid phase is likely to form a fiber-like microstructure.If Re>1024,the heat transfer becomes dominating and the liquid phase flow is suppressed,which results in the formation of fine and uniform equiaxed microstructures.展开更多
基金Projects(51171152,50871088) supported by the National Natural Science Foundation of ChinaProject(20126102110048) supported by Doctoral Fund of Ministry of Education of China+2 种基金Project(SKLSP201202) supported by Foundation of State Key Laboratory of Solidification,ChinaProject(2012JC2-02) supported by Natural Science Basic Research Plan in Shaanxi Province,ChinaProject (JC201268) supported by the NPU Foundation for Fundamental Research,China
文摘Metastable liquid phase separation and rapid solidification in a metastable miscibility gap were investigated on the Cu60Co30Cr10 alloy by using the electromagnetic levitation and splat-quenching.It is found that the alloy generally has a microstructure consisting of a（Co,Cr）-rich phase embedded in a Cu-rich matrix,and the morphology and size of the（Co,Cr）-rich phase vary drastically with cooling rate.During the electromagnetic levitation solidification processing the cooling rate is lower,resulting in an obvious coalescence tendency of the（Co,Cr）-rich spheroids.The（Co,Cr）-rich phase shows dendrites and coarse spheroids at lower cooling rates.In the splat quenched samples the（Co,Cr）-rich phase spheres were refined significantly and no dendrites were observed.This is probably due to the higher cooling rate,undercooling and interface tension.
基金the National Natural Science Foundation of China (Grant Nos. 50121101 and 50395105)the Scientific and Technological Creative Foundation of Youth in Northwestern Polytechnical University of China (Grant No. W016223)
文摘The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two sepa- rated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respec- tively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) drop- lets with the same size.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51171152 and 50871088)the Foundation for Fundamental Research of Northwestern Polytechnic University,China (Grant No. JC201268)the Fund of the State Key Laboratory of Solidification Processing,China (Grant No. SKLSP201202)
文摘（Fe50Co25B15Si10）80Cu20 ribbons are prepared by using the single-roller melt-spinning method. A dual-layer structure consisting of a （Fe, Co）-rich amorphous phase and a Cu-rich crystalline phase forms due to metastable liquid phase separation before solidification. The magnetic hysteresis loops of the as-quenched and annealed samples are measured at room temperature. It is indicated that the coercivity of the ribbon is almost zero in the as-quenched state. The crystallization leads to the increase of coercivity and decrease of saturation magnetization.
基金Funded by the National Natural Science Foundation of China(No.50274047 and 50304001)the Foundation of Ministry of Edu cation of Chinaand the Foundation of Bejing Jiaotong University
文摘The bonding of solid steel plate to liquid al uminum was studied using rapid solidification. The relationship models of interf acial shear strength and thickness of interfacial layer of bonding plate vs bond ing parameters (such as preheat temperature of steel plate, temperature of alumi num liquid and bonding time) were respectively established by artificial neural networks perfectly.The bonding parameters for the largest interfacial shear stre ngth were optimized with genetic algorithm successfully. They are 226℃ for preh eating temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8s for bonding time, and the largest interfacial shear strength of bonding pl ate is 71.6 MPa . Under these conditions, the corresponding reasonable thickne ss of interfacial layer (10.8μm) is gotten using the relationship model establi shed by artificial neural networks.
基金This project is financially supported by National Natural Science Foundation of China (No.50274047) and Advanced Technical Committee of China(No. 715-009-060)
文摘The bonding of solid steel plate to liquid aluminum was studied using rapidsolidification. The surface of solid steel plate was defatted, descaled, immersed (in K_2ZrF_6 fluxaqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at theinterface of steel-aluminum solid to liquid bonding under rapid solidification, the interface ofbonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationshipbetween bonding parameters (such as preheat temperature of steel plate, temperature of aluminumliquid and bonding time) and thickness of Fe-Al compound layer at the interface was established byartificial neural networks (ANN) perfectly. The maximum of relative error between the output and thedesired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacialshear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperatureof aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer10.8 μm was got.
文摘The bonding of solid steel plate to liquid aluminum was studied by using rapid solidification. The relationship between the bonding parameters such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time, and the interfacial shear strength of bonding plate was established by artificial neural networks perfectly. This relationship was optimized with a genetic algorithm. The optimum bonding parameters are: 226 ℃ for preheat temperature of steel plate, 723 ℃ for temperature of aluminum liquid and 15.8 s for bonding time, and the largest interfacial shear strength of bonding plate is 71.6 MPa.
基金Supported by the National Natural Science Foundation of China (Grant Nos.50121101,50395105)the Doctorate Foundation of Northwestern Polytechnical University (Grant No.CX200419)
文摘Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work,rapid solidification of an undercooled liquid Al80.4Cu13.6Si6 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The re-lationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K (0.18TE). The undercooled ternary eutectic is composed of α(Al) solid solution,(Si) semiconductor and θ(CuAl2) intermetallic compound. In the (Al+Si+θ) ternary eutectic,(Si) faceted phase grows independently,while (Al) and θ non-faceted phases grow coopera-tively in the lamellar mode. When undercooling is small,only (Al) solid solution forms as the leading phase. Once undercooling exceeds 73 K,(Si) phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary (Al) dendrite,(Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling,while at large undercooling primary (Si) block,(Al+θ) pseudo-binary eutectic and (Al+Si+θ) ternary eutectic coexist. As undercooling increases,the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases.
基金the National Natural Science Foundation of China(Grant Nos.50121101 and 50395105)
文摘The viscose flow and microstructure formation of Fe-Cu peritectic alloy melts are investigated by analyzing the velocity and temperature fields during rapid solidifi-cation,which is verified by rapid quenching experiments.It is found that a large temperature gradient exists along the vertical direction of melt puddle,whereas there is no obvious temperature variation in the tangent direction of roller surface.After being sprayed from a nozzle,the alloy melt changes the magnitude and di-rection of its flow and velocity rapidly at a height of about 180 μm.The horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-300 μm in height and a momentum boundary layer with 160-240 μm in thickness are formed at the bottom of melt puddle,and the Reynolds number Re is in the range of 870 to 1070 in the boundary layer.With the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases monotonically.The thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases sharply.If Re < 1024,the liquid flow has remarkable effects on the microstructure formation due to dominant momentum transfer.The separated liquid phase is likely to form a fiber-like microstructure.If Re>1024,the heat transfer becomes dominating and the liquid phase flow is suppressed,which results in the formation of fine and uniform equiaxed microstructures.
