共查询到20条相似文献,搜索用时 62 毫秒
1.
JIAO Yuning LIU Qingmin YANG Yuangsheng HU Zhuangqi Institute of Meta Research Chinese Academy of Sciences Shenyang ChinaGAO Yunyan JIA Guanglin ZHANG Guozhi QIAO YuanjunNortheast University Shenyang China Manuscript received May 《金属学报(英文版)》1994,7(2):145-148
Navier-Stokes equation and Lorentz force equation are used to calculate the fluid field of liquid metal of electromagnetic centrifugal casting(EMCC) in this paper.A field equationis given,which shows the azimuthal velocity closely relates to electrical conductivity,mag-netic density,viscosity of liquid metal and radius of casting.The results show that the sta-tionary magentic field can effectively restrain the fluid flow and the relative velocity be-tween liquid metal and casting mould and the velocity gradient at solid/liquid interface in-creases with rising magnetic density,which has a great effect on the solidification of liquidmetal and crystal growth characteristies. 相似文献
2.
EVOLUTION OF AS—CAST MICROSTRUCTURES OF 356 ALUMINIUM ALLOY CAST BY LIQUIDUS CASTING 总被引:1,自引:0,他引:1
A new method (liquidus casting) was used for 356 Al alloy semi-solid slurry making. The structures of 356 Al alloy cast by a Fe mould and semi-continuous casting machine at different temperatures were investigated. How the globular grains form was also discussed. The results show that either being cast by single Fe mould or semi-continuous machine, the micro structures are not conventional dendrites but fine and net-globular grains. The average gram size is smaller than 30?m and suitable enough for thixoforming, meanwhile it can improve the mechanical properties of following products. Under the suitable casting velocity and cooling intensity, most of global grains prolong their global growth and collide with each other before dendritic growth because of the large amount of the nucleation sites. 相似文献
3.
L.J.Shang A.Q.Sun J.F.Chen C.M.Zhang Q.K.Cai 《金属学报(英文版)》2004,17(5):713-718
A gradient coating of Fe-based alloy was manufactured with rare earths (RE) by plasma surfacing on Q235 steel substrate. The coatings were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM), differential thermal analyzer (DTA), and electron probe micro-analyzer (EPMA). The results show that the phases of the two kinds of coatings(with and without RE) both include α-Fe, Fe7C3, Fe3C, Cr2B, Fe2B and FeB. The microstructure of F314 coating is mainly hypereutectic, the pro-phases Cr7C3 and Cr2B are loose, crassi, spiculate and contain microcracks. The brittleness of the coating is high, and the average hardness is 787 HV. When 0.8wt% RE was added into the F314 alloy, the microstructure varied from hypoeutectic to hypereutectic continuously, The hardness appears as gradient distribution with the highest value of 773 HV, meanwhile, the brittleness decreases significantly. The formation of gradient structure depends on the fallowing factors: (i) the conversion of RE. The addition of RE lowers the elements point and Fe-C eutectic temperature, thus the base metal melting acutely. (ii) the heating of plasma arc.Graded temperature results in directional solidification, thus the gradient structure forms easily. The main reasons for the hardness decrease with RE addition in the alloy are the ratio of hard phase lowering and the hardness of the hard phase decreasing. 相似文献
4.
EVOLUTIONOFMICROSTRUCTUREINOXIDATIVEGROWTHOFAl_2O_3/AlALLOYCOMPOSITES¥XiaChangqing;JinZhanpeng(DepartmentofMaterialsScienceand... 相似文献
5.
REHEATING TEMPERATURE CONTRAST AND MICROSTRUCTURES OF 7075 Al ALLOY CAST BY LIQUIDUS SEMI-CONTINUOUS CASTING 总被引:4,自引:0,他引:4
J. Dong G.M. Lu J.Z. CuiThe Key Lab. of Electromagnetic Processing of Material Ministry of Education Northeastern University Shenvane China 《金属学报(英文版)》2002,(6)
In this study, reheating of liquidus semi-continuous cast billets of 7075 Al alloy was carried out in a resistance furnace, and the temperature contrast of the outer and the center of the reheated billets was investigated, then the reheating microstructures were investigated. Results show that: the difference of temperature between the outer and center is small and the difference of their microstructures are also small. During reheating at 576℃ the spheroidization of grains is significant after 5min and no rosettes are visible after 20min by optical microscopy. Similar observations were madeon materials reheated at 596℃, but the ripening process is faster. The grains growup to 30-60μm, fine enough for thixoforming. 相似文献
6.
7.
QUENCH IN STABILIZATION OF Cu-Zn-Al ALLOY 总被引:1,自引:0,他引:1
Peng Kun Tan Shusong Li Shutang Department of Materials Science Engineering Central South University of Technology Changsha Chung C Y Lam C W H Department of Physics Materials Science City University of Hong Kong Tat chc 《中国有色金属学会会刊》1997,(3)
QUENCHINSTABILIZATIONOFCuZnAlALLOY①PengKun,TanShusong,LiShutangDepartmentofMaterialsScienceandEnginering,CentralSouthUniver... 相似文献
8.
Li Yichun General Research Institute For Non-ferrous Metals Beijing China Shao Wenzhu An Xiyun Harbin Institute of Technology Harbin China 《中国有色金属学会会刊》1993,(3)
The process of aging precipitation in SiC_p/6061 and Al_2O_3/6061 composites were investigated. Hardness testing, differential scanning calorimetry(DSC) and transmission electron microscopy were employed. Results showed that the precipitation phase form directly along dislocation lines in the composites because the particles produce high densities of dislocations which makes vacancy densities in the composites decrease, and the main precipitation phase at peak hardness was β′ phase. 相似文献
9.
Wu Chao Wang Pinglong Meng Tingrang Department of Resources Exploitation Engineering Central South University of Technology Changsha 《中国有色金属学会会刊》1997,(1)
INSITUMEASUREMENTOFBREEDINGFIREOFSULPHIDEOREDUMPS①WuChao,WangPinglong,MengTingrangDepartmentofResourcesExploitationEnginerin... 相似文献
10.
MICROSTRUCTURE ANALYSIS AND MECHANICAL PROPERTIES OF Zn—Al ALLOY ROD PRODUCED BY HEATED MOLD CONTINUOUS CASTING 总被引:1,自引:0,他引:1
The new technology of continuous casting by heated mold was used to produce directional solidification ZA alloy lines to eliminate the inter defects of these lines and increase their mechanical properties. The results are as follows: (1) The microstruc-ture of the ZA alloy lines is the parallel directional dendritic columnar crystal. Every dendritic crystal of eutectic alloy ZA5 was composed of many layer eutectic β and η phases. The micro structure of hypereutectic ZA alloys is primary dendritic crystal and interdendritic eutectic structure. The primary phase of ZA8 and ZA12 is β, among them, but the primary phase of ZA22 and ZA27 is a. (2) Through the test to the as-cast ZA alloy lines made in continuous casting by heated mold, it is found that the tensile strength and hardness increase greatly, but the elongation decreases. With the increase of aluminum amount from ZA 5 to ZA 12, ZA22 and ZA27, the tensile strength increases gradually. ZA27 has the best comprehensive mechanical properties in these 相似文献
11.
LIU Qingmin JIAO Yuning YANG Yuamheng HU ZhuangqiInstitute of Metal Research. Chinese Academy of Sciences Shenyang China Manuscript received April 《金属学报(英文版)》1994,7(2):107-113
A theoretical analysis was presented to produce gradient composite by centrifugal casting.particle movement in liquid metal is described and gradient distribution of particles in com-posite is calculated in a centrifugal field.The factors affected the gradient distribution are discussed in detail .There exist composite zone and blank zone in(?)radient composite.whichwas proved by experiments. Finally,a theoretical analysis is given to explain the abovementioned particle distribution. 相似文献
12.
Wu Jinming Wu Nianqiang Wang Guangxin Li Zhizhang Department of Materials Science Engineering Zhejiang University Hangzhou 《中国有色金属学会会刊》1997,(3)
INSITUOBSERVATIONOFSINGLE-POINTWEAROFPMAlTiALLOY①WuJinming,WuNianqiang,WangGuangxin,LiZhizhangDepartmentofMaterialsSciencea... 相似文献
13.
原位Al2O3和TiB2粒子增强Al-Cu合金基复合材料的制备和性能 总被引:9,自引:4,他引:5
由TiO2AlBCuO体系制备了原位Al2O3和TiB2粒子增强Al3.2%Cu和Al6.0%Cu合金基复合材料。X射线衍射分析表明,在两种复合材料中均有Al2O3和TiB2生成,没有发现Al3Ti相产生。原位生成的Al2O3和TiB2粒子为尺寸小于2μm的等轴状粒子,在Al基体中均匀分布。室温拉伸试验表明两种AlCu合金基原位复合材料具有很高的强度,并且随着基体合金中Cu含量的增加复合材料的强度增加。动态压缩试验表明,这种AlCu合金基原位复合材料的强度对应变速率是不敏感的,这可由不同应变速率变形后的复合材料基体中位错密度大致相同来解释。高温压缩蠕变试验表明,两种复合材料均表现出高的显态应力指数。随基体合金中Cu含量的增加复合材料的蠕变抗力明显提高。 相似文献
14.
原位Al2O3颗粒强化铝基复合材料的研究 总被引:12,自引:0,他引:12
研究了铝熔体内的原位反应Al CuO工艺对反应诱导时间、剧烈程度及产物分布的影响。结果表明随着稀释剂Al量的增多,熔体内自曼燃反应启动越慢,剧烈程度降低,反应产物的分布朝不均匀方向变化;熔体的温度越高,反应启动得越快,越剧烈;引发剂镁粉的添加极大地缩短反应诱导时间,制备了原位AlO3颗粒强化 含不同产物Cu的铝基复合材料,SEM观察表明铸造条件下Al2O3颗粒小于0.5μm,均匀地分布在材料的各种基体相上;随着Al2O3颗粒的增多,产物Cu以网状化合物形式分布,拉伸实验显示材料的塑性很低,为降低Cu量,在原反应物中混合入SiO2粉,或采用喷射沉积快速凝固法细化组织,提高固溶量。SEM显示网状相得到了细化和均匀分布,拉伸实验表明强度和塑性有大幅度提高。 相似文献
15.
利用透射电镜对2091铝锂合金在不同热处理状态下的变形断裂过程进行了原位观察,结果表明,在不同的时效状态,合金的应变局部化不同,在近峰值时效合金变形时,位错切割δ′相而产生强的共面滑移,引起应变不均匀;而在过时效态合金中,应变集中于晶界PFZ内,晶内的共面滑移带明显减弱 相似文献
16.
AN IN SITU SURFACE COMPOSITE AND GRADIENT MATERIALOF Al-Si ALLOY PRODUCED BY ELECTROMAGNETIC FORCE 总被引:1,自引:0,他引:1
Z.M. Xu T.X. Li Z.L. Zhu Y.H. Zhou School of Materials Science Engineering Shanghai Jiao Tong University Shanghai China 《金属学报(英文版)》2001,14(5):335-340
1. IntroductionAt present, the main processes fOr producing surface composite and gradient materialduring solidiflcation are casting infiltrationl1,2], electromagnetic stirring to separate eutec-tic process of the eutectic alloy[3l4], electromagnetic ..nt.iiug.l casting[5--7] and centrifugalcasting[s]. These processes, however, are complicated and require complex equipment;therefore, they are limited in application. The aim of this research is to develop a newmethod for production of in situ s… 相似文献
17.
采用一种新颖的离心成型法制备了无宏观界面的Al2O3/Ni功能梯度材料, 并研究了料浆调制工艺、离心成型制备机理和梯度材料的力学性能。结果表明, 配制料浆时,粘结剂(聚乙二醇)含量为2 mass%、固相含量为63vol.%、球磨时间为36h,可得到流动性良好的料浆,经离心成型(40min,转速3000 r/min)得到无宏观界面的坯体,在1400 C真空烧结2 h,最终得到致密、组元宏观连续过渡的Al2O3/Ni梯度材料。通过调整固相含量和粘结剂含量,可调控Al2O3/Ni复合材料的成分梯度。 相似文献
18.
EFFECT OF ROTATING MAGNETIC FIELD ON MACROSTRUCTURE OF A CENTRIFUGAL CASTING Al-1%Cu ALLOY 总被引:1,自引:0,他引:1
1. IntroductionCelltrifugal casting has been broadly used as it offers many advantages over the conventional casting methods. In a celltrifugal casting process, liquid metal is introduced intoa die that is spinning at a high rotational speed. The metal will take the shape of the dieand be subjected to a force 40 to 50 times of gravityg which then usually makes the castmore dense. The cast is also very clean, since the non-metallic inclusions that are presentin the liquid metal are celitrifuged… 相似文献
19.
Y.Ma Y.Hao S.Z.Kou X.N.Lu 《金属学报(英文版)》2004,17(5):732-740
Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the system is set up, and the influence of resultant concentration and temperature on adiabatic temperature is theoretically analyzed. The values of heat effect of CuO/Al system under different temperature are also caculated. 相似文献