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| 1 | Morphologies of Fe-66.7 at.%Si alloy solidified in a drop tube显示文摘Solidification of 0.1―1.0 mm diameter droplets of Fe-66.7 at.%Si alloy was achieved in a 3 m drop tube. The XRD, EDS, and SEM measurements reveal that all the droplets are composed of the primary phase α and the α+ε eutectic. With decreasing droplet diameter, the growth mode of the primary phase α changes from faceted to nonfaceted growth and the eutectic changes from needle-like to anomalous eutectic. In addition, the width of the primary phase α decreases with decreasing droplet size. The different cooling rates and undercooling levels corresponding to the samples with different sizes are responsible for the morphology changes. The cooling rates of the samples with different diameters during free fall were calculated and their effects on the microstructure formation were discussed. This kind of transition is also found inside the same sample, which is due to the larger cooling rate on the surface than at the center. | WANG Haiyan1,2, LIU Riping1, MA Mingzhen1, JING Qin1, LI Gong1, SUN Liling2 & WANG Wenkui1,2 1. Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China 2. Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China | 2005 | Science China(Physics,Mechanics & Astronomy)2005，48，6： | 5 |
| 2 | Effect of interface kinetics on the eutectic growth显示文摘The atom-attachment kinetics at the solid-liquid interface was incorporated into the eutectic growth theory. The dependence of kinetic undercooling on the structure of the eutectic phases was investigated. Due to the introduction of the kinetic effect, the coupled eutectic growth can proceed in a wider undercooling range, but the growth velocity decreases while the minimum eutectic lamellar spacing remains unchanged. The proportion of kinetic undercooling to the total undercooling is dependent not only on the growth velocity, but also on the phase diagram. Calculation indicated that the proportion decreases as the crystallization temperature range of single eutectic phase at the eutectic composition enlarges. | LI Jinfu ZHOU Yaohe | 2005 | Science China(Technological Sciences)2005，48，4： | 4 |
| 3 | Rapid monotectic solidification under free fall condition显示文摘Fe-48.8% Sn monotectic, Fe-40% Sn hypomonotectic and Fe-58% Sn hypermonotectic alloys have been rapidly solidified during free fall processing in drop tube. For droplets of 100—1000 mm, the maximum undercooling for Fe-48.8% Sn, Fe- 40% Sn and Fe-58% Sn alloys is 270, 282 and 288 K respectively. For Fe-48.8% Sn monotectic alloy, a homogeneously dispersed microstructure can be obtained when the droplet diameter is small, and the Marangoni migration velocity Vm is 37 times as fast as Stokes velocity Vs when the dispersion sphere radius is 6 mm and undercooling is 30 K. For Fe-40% Sn hypomonotectic alloy, the microstructure undergoes a transition from columnar a-Fe dendrites distributed in Sn-rich matrix to a-Fe particles. The growth velocity of a-Fe dendrite changes from 0.45 to 4.65 m/s when the droplet diameter varies from 1000 to 100 mm. For Fe-58.8% Sn hypermonotectic alloy, the grain size of primary a-Fe dendrites decreases remarkably when undercooling increases. | LIU Xiangrong LU Xiaoyu WEI Bingbo | 2004 | Science China(Technological Sciences)2004，47，4： | 3 |
| 4 | COUPLED NUMERICAL SIMULATION OF STEEL FLOW AND SOLIDIFICATION IN SOFT-CONTACT BILLET MOLD显示文摘A coupled model including electromagnetic field, fluid dynamic, heat transfer and so-lidification, is developed and applied to the numerical simulation of steel flow andsolidification in a 100mm× 100mm soft-contact mold. In this study, the 3D finite dif-ference method and n, on-staggered grid system for fluid flow with body fitted coordinatewere employed. Numerical results show that the electromagnetic force mainly affectsthe steel flow at upper part of mold, especially in the vicinity of meniscus. There existupward flows covering the surfaces of the billet due to the concentration of electro-magnetic force on the upper part of the billet. This flows join together and form adownward flow near the SEN, so a distinct circulating flow zone is formed at upperpart of mold. After applying electromagnetic force, the steel velocity is improved andthe temperature is raised. The strong stirring of electromagnetic force on liquid steelmakes the kinetic energy on free surface increase. It is clearly seen that the solidifi-cation start point shifts downward in soft contact mold. As a result, the initial shellthickness gets thin and the initial solidification shell length is shortened. | A.Y. Deng and J.C. HeKey Laboratory for Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China | 2002 | Acta Metallurgica Sinica(English Letters)2002，15，5： | 2 |
| 5 | Pattern and phase selection of peritectic reaction during directional solidification显示文摘Based on the growth competition between different pattern and phases, the pattern and phase selection during peritectic solidification is analysed by applying the maximum interface temperature criterion to the interface response functions calculated from a numerical model for single phase solidification. The theoretical results agree very well with the experimental results published in literature. | 黄卫东 林鑫 王猛 沈淑娟 苏云鹏 刘振侠 | 2002 | Science China(Technological Sciences)2002，45，5： | 2 |
| 6 | Study on undercooling of metal droplet in rapid solidification显示文摘A mathematical model for the undercooling of the metal droplet during the rapid solidification is established, by which the factors that influence the undercooling of the metal droplet during the rapid solidification are analyzed, and the parameter ζ=σSL3/ (TL?H 2 ) is defined as the impact factor of the undercooling for the droplet solidification. Different undercoolings of droplets induced by various rapid solidification conditions are mainly ascribed to the change of the impact factor. Moreover, it is shown that the larger of ζ, the higher the relative undercooling can be gained. Meanwhile, the parameters such as solid-liquid interfacial energy σSL and latent heat of solidification ?H also vary with the rapid solidification conditions of droplets. | GAO Yulai GUAN Wanbing ZHAI Qijie XU Kuangdi | 2005 | Science China(Technological Sciences)2005，48，6： | 2 |
| 7 | Microstructure evolution of laser rapidly solidified Al-Mn alloys显示文摘A series of laser surface remelting experiments of Al-1.1, 3.2 and 5.6 wt% Mn alloys has been conducted using a 5 kW CW CO2 laser, and the microstructures of samples have also been investigated. The experimental results show that no apparent eutectic growth appears in the whole growth rate range for Al-3.2 wt% Mn alloy under laser rapid solidification condition, and the microstructure grows in the form of α(Al) cell/dendrite. With the increase of growth rate, the microstructures of Al-5.6wt%Mn alloy change from Al6Mn dendrite to α(Al) +Al6Mn eutectic, α(Al) cellular/dendrite and segregation-free solid solution. The critical rates of Al-1.1, 3.2 and 5.6 wt% Mn alloys to attain absolute stability are 44.1, 134.6 and 230.1 mm/s respectively, and a reasonable agreement has been found between the experimental results and those calculated according to Mullins-Sekerka's theory. | YANG Sen, HUANG Weidong, LIU Wenjin and ZHOU Yaohe(1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China 2. Department of Materials Science and Engineering, Inner Mongolia Polytechnic University, Hohhot 010062, China 3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China) | 2002 | Progress in Natural Science:Materials International2002，12，9： | 1 |
| 8 | Numerical and Experimental Studies of Substrate Melting and Resolidification during Thermal Spraying显示文摘A good understanding of melting and resolidification of the substrate will help us to achieve better bonding. Anumerical model is developed to investigate the solidification of the droplet, and melting and resolidification of thesubstrate. The molybdenum powder spraying onto three different substrates: a stainless steel, brass (70%Cu) andaluminum by atmospheric plasma spraying has been investigated. The maximum melting depth of the substrate hasbeen measured and compared with the numerical prediction. Experimental results show that the material propertiesof the splat and substrate and melting temperature of the substrate play the important roles on substrate melting.A dimensionless parameter, temperature factor, has been proposed and served as an indicator for substrate melting. | H. Zhang G. Wei L.Zheng L.Li X. Y. Wang A. Vaidya | 2003 | Journal of Materials Science & Technology2003，19，z1： | 1 |
| 9 | Additional force field in cooling process of cellular Al alloy显示文摘The foaming process of Al alloy is similar to that of Al, but there is a solid-liquid state zone in the solidification process of cellular Al alloy which does not exist in the case of Al. In the unidirectional solidification of cellular Al alloy, the proportion of the solid phase gradually reduces from the solid front to the liquid front. This will introduce a force and result in a serious quick shrinkage. By the mathematic and physical mode, the solidification of the cellular Al alloy is studied. The data measured by experiment are close to the result calculated by the mode. This kind of shrinkage can be solved by suitable cooling method in appropriate growth stage. The compressive strength of the cellular Al alloy made by this way is 40% higher than that of cellular Al. | 郑明军 何德坪 戴戈 | 2002 | Science China Chemistry2002，45，6： | 1 |
| 10 | A new coupled model for alloy solidification显示文摘A new coupled model in the binary alloy solidification has been developed. The model is based on the cellular automaton (CA)technique to calculate the evolution of the interface governed by temperature, solute diffusion and Gibbs-Thomson effect. The diffusion equation of temperature with the release of latent heat on the solid/liquid (S/L) interface is valid in the entire domain.The temperature diffusion without the release of latent heat and solute diffusion are solved in the entire domain. In the interface cells, the energy and solute conservation, thermodynamic and chemical potential equilibrium are adopted to calculate the temperature, solid concentration, liquid concentration and the increment of solid fraction. Compared with other models where the release of latent heat is solved in implicit or explicit form according to the solid/liquid (S/L) interface velocity, the energy diffusion and the release of latent heat in this model are solved at differentscales, I.e. The macro-scale and micro-scale. The variation ofsolid fraction in this model is solved using several algebraicrelations coming from the chemical potential equilibrium andthermodynamic equilibrium which can be cheaply solved insteadof the calculation of S/L interface velocity. With the assumptionof the solute conservation and energy conservation, the solidfraction can be directly obtained according to the thermodynamicdata. This model is natural to be applied to multiple (>2)spatial dimension case and multiple (>2) component alloy. Themorphologies of equiaxed dendrite are obtained in numericalexperiments. | LI Daming LI Ruo ZHANG Pingwen | 2004 | Science China Mathematics2004，47，z1： | 0 |
| 11 | Undercooling and solidification of germanium melts studied by differential scanning calorimeter显示文摘Differential scanning calorimeter combined with flux(dehydrated B2O3) processing was used to realize and precisely measure the undercooling of germanium melts.The highest undercooling obtained in this way was 190 K.Relations between the undercooling and cooling rate or overheating tem-perature are analyzed respectively.The undercooling obtained is found to be increased with increasing of the cooling rate in the range from 5 to 40 K/min.At a given cooling rate,the undercooling reached is increased with the increasing of the overheating temperature of the melt,but tends to be constant at last.Crystallization of the undercooled germanium melt is investigated at the same time.It is clearly shown that,the higher the cooling rate,the shorter time is needed for crystallization. | LI Qiang1,2,ZHU Yuying2,HE Yunha3,WANG Xu2,LI Gong1,YU Jinku1 & SU Zhibin1 1.Key Laboratory of Metastable Materials Science &Technology,Yanshan University,QinhuangdaO 066004,China 2.Department of Mechanical Engineering,Yanshan University,Qinhuangdao 066004,China 3.Department of Environmental & Chemical Engineering,Yanshan University,QinhuangdaO 066004. China | 2004 | Science China(Physics,Mechanics & Astronomy)2004，47，5： | 0 |
| 12 | Nonlinear instability and dynamic bifurcation of a plane interface during solidification显示文摘By taking average over the curvature, the temperature and its gradient, the solute con-centration and its gradient at the flange of planar interface perturbed by sinusoidal ripple during solidifi-cation, the nonlinear dynamic equations of the sinusoidal perturbation wave have been set up. Analysisof the nonlinear instability and the behaviors of dynamic bifurcation of the solutions of these equationsshows that (i) the way of dynamic bifurcation of the flat-to-cellular interface transition vades with differ-ent thermal gradients. The quasi-subcritical-lag bifurcation occurs in the small interface thermal gradientscope, the supercritical-lag bifurcation in the medium thermal gradient scope and the supercritical bifur-cation in the large thermal gradient scope. (ii) The transition of cellular-to-flat interface is realizedthrough supercritical inverse bifurcation in the rapid solidification area. | 吴金平 侯安新 黄定华 鲍征宇 高志农 屈松生 | 2001 | Science China(Technological Sciences)2001，44，5： | 0 |
| 13 | Nonlinear Theory on Dynamic Controlling Interface Patterns DuringSolidification of a Dilute Binary Alloy显示文摘Nomenclaturea,bfcorrectnessfactors;aL,Qs'thermaldiffusivitiesofliquidandsolid,respectively,C:concentrationofsolute,D,'diffusioncoefficientofsolute;G,'concentrationgradient;G,,G,'temperaturegradientsofliquidandsolid,respectively,k'partitioncoefficient... | Zidong Wang Hanqi Hu(Material Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China) | 1999 | International Journal of Minerals,Metallurgy and Materials1999，13，4： | 0 |
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