检索结果-南通市图书馆

Thermophysical properties of Ni-5%Sn alloy melt

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2006年第2期49卷 236-245页

作者： dai fuping cao chongde {3. bingbo Laboratory of Materials Science in Space Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China Laboratory of Materials Science in Space Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China Laboratory of Materials Science in Space Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China

The surface tension and specific heat of Ni-5%Sn alloy melt were measured by the oscillating drop method and the drop calorimetric method using electromagnetic levitation, respectively. The temperature coefficient of surface tension is 6.43.10-4 N·m?1K?1 within the temperature regime of 1464-193. K. The enthalpy change was measured in the temperature range from 1461 to 1986 K, and the average specific heat was obtained as 43.03.J·mol?1K?1. Some other thermophysical properties, such as viscosity, solute dif-fusion coefficient, density, thermal diffusivity and thermal conductivity of this alloy melt, were derived based on the experimentally measured surface tension and specific heat. Using these thermophysical parameters, the relation between solute trapping and under-cooling in rapidly solidified α-Ni was calculated, and the theoretical prediction shows a good agreement with experimental data.

关键词： Thermophysical properties Surface tension Specific heat melt alloy Undercooling.

Rapid dendritic growth of Al-Ge hypoeutectic alloy in a drop tube

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2003年第2期 79-82页

作者： LIU Xiangrong, cao chongde and wei {3.(department of applied physics, northwestern polytechnical university, Xi’an 710072, china) department of applied physics Northwestern Polytechnical University Xi'an 710072 China

Abstract Dendritic growth in Al-45% Ge hypoeutectic alloy has been investigated during free fall in a 3.m drop tube. Calculationsindicate that the undercooling obtained for the falling Al-45% Ge droplets ranges from 13.K to 201 K. The maximum undercooling attains0. 27 TL. With the increase of undercooling, the primary (Al) phase undergoes a "columnar dendrite to equiaxed dendrite" structural tran-sition. According to the current rapid dendritic growth theory, the growth of primary (Al) phase is always controlled by solute diffusion.

关键词： dendritic growth undercooling containerless processing Al-Ge alloy.

Rapid solidification of Al-Cu-Ag ternary alloy under the free fall condition

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2009年第6期52卷 848-855页

作者： dai fuping wei bingbo department of applied physics Northwestern Polytechnical UniversityXi’an 710072China

The rapid solidification of Al-3.%Cu-18%Ag ternary alloy is investigated by using the free fall method. Its solidified microstructure is composed of θ(Al2Cu), α(Al) and ξ(Ag2Al) phases. The liquidus temperature and solidus temperature are determined as 778 and 827 K, respectively. The alloy melt undercooled amounts up to ΔTMax=171 K (0.20TL). Its microstructural evolution is investigated based on the theoretical analysis of undercooling behavior and nucleation mechanics. It is found that the undercooling increases with the decrease of the diameter of the alloy droplet. When ΔT<78 K, the primary θ (Al2Cu) phase of the alloy grows into coarse dendrite. When 78 K≤ΔT≤171 K, its refined θ (Al2Cu) phase grows alternatively with α(Al) phase. Once ΔT≥171 K, its microstructure is characterized by the anomalous (θ+α+ξ) ternary eutectic.

关键词： Al-Cu-Ag free fall nucleation ternary eutectic rapid solidification high undercooling

Rapid growth of ternary eutectic un der high undercooling conditions

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2004年第6期47卷 717-728页

作者： RUAN Ying cao chongde wei {3. department of applied physics Northwestern Polytechnical University Xi'an 710072 China Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China

Rapid solidification of bulk Ag42.4Cu21.6Sb3. ternary eutectic alloy is accomplished by glass fluxing method,during which the maximum undercooling attains 114 K (0.16 TE). Under high undercooling conditions,the ternary eutectic consists ofε (Ag3.b),(Sb)and θ(Cu2Sb)phases,instead of (Ag),(Sb)and θphases as predicted by the phase *** the sample of small undercooling,the alloy microstructure is characterized by the mixture of primary θ(Cu2Sb),(ε+θ) and (ε+Sb) pseudobinary eutectics,and regular (ε+θ+Sb) ternary *** the increase of undercooling, θ (Cu2Sb) primary phase and pseudobinary eutectics disappear gradually,and ternary eutectic transfers from regular to anomalous *** undercooling exceeds 102 K,anomalous (ε+θ+Sb) ternary eutectic is the unique *** nucleation and growth of these three eutectic phases is the main cause for the formation of complex growth *** on the current experiments and theoretical calculations,it can be concluded that the intermetallic compound phaseθ(Cu2Sb) is the leading nucleating phase.

关键词： eutectic growth, crystal nucleation, high undercooling, ternary eutectic.

Rapid growth of primary dendrite in highly undercooled copper-antimany alloy

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2002年第12期12卷 57-61页

作者： YAO Wenjing , cao chongde and wei {3.(Laboratory of Materials Science in Space, department of applied physics, northwestern polytechnical university, Xi’an 710072, china) northwestern Polytech Univ Dept Appl Phys Lab Mat Sci Space Xian 710072 Peoples R China

The droplets of Cu-11wt. %Sb hypoeutectic alloy have been rapidly solidified during containerless processing in a 3.m drop tube. The undercooling and cooling rates are estimated, and both play a dominant role in the dendritic growth of primary Cu phase. Undercoolings up to 200 K (0. I&TL, where TL is the liquidus temperature) have been obtained in the experiment. With the increase of undercooling, the microstructural evolution of primary Cu phase proceeds from remelted dendrites to the equiaxed grains. A coarse dendritic grain microstructure can form in the undercooling range of 61 - 102K and at cooling rates of 1.3.X 102-2.66X 103./s. The seg-regationless solidification of Cu-llwt. %Sb hypoeutectic alloy occurs when undercooling is more than 176 K. The growth of primary Cu phase is mainly controlled by solute diffusion.

关键词： rapid growth undercooling copper dendrlte drop tube.

Heat and mass transfer characteristics during rapid solidification of Fe-Cu peritectic alloys

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2008年第5期51卷 459-469页

作者： XU JinFeng dai fuping wei bingbo department of applied physics Northwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China

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 *** 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 *** 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 μ*** horizontal flow velocity increases rapidly,but the vertical flow velocity decreases sharply.A thermal boundary layer with 160-3.0 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 *** the increase of Re number,the cooling rate increases linearly and the thickness of thermal boundary layer increases *** thickness of momentum boundary layer decreases slowly at first,then rises slightly and decreases *** 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.

关键词： peritectic alloy liquid phase separation fluid flow heat transfer rapid solidification

Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2007年第4期50卷 472-490页

作者： WANG weiLi dai fuping wei {3. department of applied physics Northwestern Polytechnical UniversityXi’an 710072China

The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic com- pound may grow cooperatively within ternary eutectic microstructures, they sel- dom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of sol- ute solubility.

关键词： undercooling dendritic growth eutectic growth ternary eutectic solute trapping

Dendritic growth and solute trapping in rapidly solidified Cu-based alloys

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2011年第5期54卷 901-908页

作者： SONG RuiBo dai fuping wei bingbo department of applied physics Northwestern Polytechnical University Xi'an 710129 China

Rapid solidification of binary Cu-22%Sn peritectic alloys and Cu-5%Sn-5%Ni-5%Ag quaternary alloys was accomplished by glass fluxing, drop tube and melt spinning methods. The undercooled, by glass fluxing method, Cu-22%Sn peritectic alloy was composed of a（Cu） and δ（Cu41Snll） phases. If rapidly solidified in a drop tube, the alloy phase constitution changed from α（Cu） and δ（Cu41Sn11） phases into a single supersaturated （Cu） phase with the reducing of droplet diameter, and the maximum solubility of Sn in （Cu） phase extended to 22%. The Cu-5%Sn-5%Ni-5%Ag quaternary alloy was composed of （Cu） and （Ag） phases under the containerless processing condition in a drop tube, and the solute microsegregation of （Cu） phase was obvious. When the Cu-5%Sn-5%Ni-5%Ag quaternary alloy was solidified by melt spinning method, microsegregation was suppressed and solute trapping occurred. The experimental results show that the microstructures of primary （Cu） phase in the two alloys transfer from coarse dendrites into equiaxed grains with the increase of cooling rate and undercooling, which is accompanied by the grain refinement effect.

关键词： Cu-based alloy rapid solidification dendritic growth solute trapping

Solidification microstructure and phase constitution of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第16期55卷 1674-1678页

作者： LI Li LU XiaoYu cao chongde dai fuping department of applied physics Northwestern Polytechnical University Xi'an 710072 China

Solidification of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy is investigated by using differential scanning calorimetry (DSC) and drop tube containerless processing *** primary phase is identified as R (Fe5Mo3.i2) and the quasiperitectic phases are τ1 (Fe5MoSi4) and *** the decrease of droplet diameter, the cooling rate and undercooling of the droplets in-crease *** experiment result indicates that the solidification microstructure is composed of remnant primary phase, qua-siperitectic phases and ternary eutectic when the droplet diameter exceeds 400 μm, whereas the ternary eutectic is suppressed when the droplet is smaller than 400 μm in diameter.

关键词：三元合金凝固微观组织硅合金 Fe 差示扫描量热法液滴直径宪法钼