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 12 May
,
1994
金属学报(英文版)
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 equation is given, which shows the azimuthal velocity closely relates to electrical conductivity, magnetic density, viscosity of liquid metal and radius of casting. The results show that the stationary magnetic field can effectively restrain the fluid flow and the relative velocity between liquid metal and casting mould and the velocity gradient at solid / liquid interface increases with rising magnetic density, which has a great effect on the solidification of liquid metal and crystal growth characteristics.
关键词:
fluid field of liquid metal
,
null
BAL■ P
,
ACHIMOVI■OV M
,
SEPLAK VInstitute of Geotechnics of Slovak Academy of Sciences
,
Kosice
,
SlovakiaBASTLZJ.Heyrovsky Institute of Physical Chemistry
,
Academy of Sciences of the Czech Republic
,
Prague
,
C. R. LIPAKJSlovak Technical University
,
Electrotechnical Faculty
,
Bratislava
,
Slovakia Manuscript received 22 February
,
1994
金属学报(英文版)
The mechanical activation of tetrahedrite Cu_(12)Sb_(4)S_(13) was carried out in a planetary mill. The changes in the surface and bulk properties produced in mineral by mechanical activation were detected by infrared, photoelectron and Mossbauer spectroscopy. The rate and selectivity of tetrahedrite acid leaching depends on conditions of mechanical activation.
关键词:
mechanical activation
,
null
,
null
LI MeiyaShantou University
,
Shantou
,
Guangdong
,
ChinaCOWLAMNUniversity of Sheffield
,
Sheffield S3 7RH
,
UKCOCCOGUniversita di Sassari
,
via Vienna 2
,
07100 Sassari
,
Italy Manuscript received 10 May
,
1994
金属学报(英文版)
Small angle neutron scattering(SANS) technique has been used to investigate the Ni_(50)Mo_(50) system prepared by mechanical alloying(MA). Significant changes of the scattering intensity have been observed among the samples with different milling time.Interesting fractal-like behavior of the sample system have been found and attempts have been made to determine the fractal dimensions. It is expected that the fractal dimension can be related to the different stages of MA to some extent.
关键词:
mechanical alloying
,
null
,
null
ZHANG Haifeng
,
LIJie
,
SONG Qihong
,
HU ZhuangqiInstitute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
ChinaLI WenShenyang Institute of Technology
,
Shenyang. China Manuscript received 26 April
,
1994
金属学报(英文版)
Amorphous Ni-Pd-Si ribbons were partially crystallized by relaxation treatment then secondary amorphous Ni-Pd-Si alloy powder prepared by mechanical milling. The surface states of amorphous and crystalline Ni-Pd-Si powders were studied by XRD, TEM, AES and ESCA spectra. The catalytic activities of amorphous and crystalline powders in hydrogenation of styrene was measured.The result shows that the catalytic activity of amorphous Ni-Pd-Si powder was higher than that of crystalline one by 6 times in hydrogenation of styrene.
关键词:
Ni-Pd-Si alloy
,
null
,
null
PA N JinChangsha Institute of Technology
,
ChinaLI Jihong
,
NING Xiaoguang
,
YE HengqiangLab. of Atomic Imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences. Shenyang
,
China Manuscript received 28 February
,
1994
金属学报(英文版)
A newly developed whisker K_(2)O 6TiO_(2) reinforced 6061 Al composite was prepared by squeeze casting process. The flexural strength of the composite is 518MPa, and decreases to 490 M Pa after T6 treatment.The hardness of the composite also shows the similar change while T6 treating. The results of HRTEMobservation may explaine this property change. It was considered that there is a continuous TiO layer at the whisker-matrix interface, which is easily to react with the segregated Mg and to form MgTi_(2)O_(4), MgAl_(2)O_(4). The thickening of TiO layer after T6 treatment is the main reason resulting in strength degradation of composite.
关键词:
potassium titanate. whisker
,
null
,
null
GAO Ruwei
,
XIAO MingshanShandong University
,
Jinan
,
ChinaZHOU Shouzeng
,
LIFubiao
,
ZHANG LidongNational Laboratory
,
University of Science and Technology Beijing
,
China Manuscript received 11 April
,
1994
金属学报(英文版)
The effect of the orientation magnetic field on the permanent magnetism of Nd-Fe-B sintermagnets is investigated. The results show that the variation law of magnetism with orientation field obviously changes at the critical orientation field and the intensity of the orientation field should he determined by the dimension ratio of the magnet for effectively utilizing its magnetic energy product.
关键词:
orientation magnetic field
,
null
,
null
,
null
MA Zhongyi
,
LU Yuxiong
,
BI JingInstitute of Metal Research
,
Chinese Academy of Sciences. Shenyang
,
ChinaZHANG YuzhengNortheastern University
,
Shenyang. China Manuscript received 16 May
,
1994
金属学报(英文版)
The tensile tests on the silicon carbide whisker and paniculate reinforced 2124A1 and 2024Al alloy composites fabricated by P/ M technique were carried out at the temperatures ranging from room temperature to - 196C . and the fracture surfaces were examined. The cryogenic strength of the composites increases with the decreasing test temperature. Clean interface is beneficial to the improvement in cryogenic strength of the composites. The effect of the interface characteristics on the paniculate composite is less than that on the whisker composite. With the decreasing temperature, the increase in strength of the whisker composite is more than that of the paniculate composite, which could be attributed to different strengthening mechanism.
关键词:
composite
,
null
,
null
,
null
GAO Wen and LI ChunzhiInstitute of Aeronautical Materials
,
Beijing
,
Beijing Laboratory of Electron Microscopy
,
Chinese Academy of Sciences
,
Beijing
,
China Manuscript received 11 April
,
1994
金属学报(英文版)
The mierostructure of an AuNiFeCrlnZr alloy has been studied by means of TEM,CBED. SEM and EDS. The results show that the alloy contains Au-rich solid solution, Ni-rich solid solution, and η- and -ωphases. The η-phase containing 90at%Cr possesses an orlhorhombic .structure with a = 0.448nm. b = 1.40nm and c = 1.21nm, and space group of Pmm2 or Pmmm. The ω-phase is an fee structure with a = 0.682nin and space group of Fm3m. The ω-phase dispersed in the alloy matrix plays an important role in increasing strength and wear resistance of the alloy.
关键词:
Au-base alloy
,
null
,
null
,
null
CAl Yingwen
,
MAO Xiemin
,
LI Jianguo
,
FU HengzhiNorthwestern Polytechnieal University
,
Xi'an
,
China Manuscript received 14 March
,
1994
金属学报(英文版)
Theoretical model for non -equilibrium solidification is constructed with consideration of diffuse interface and multiphase fluctuation. It can he degenerated to Aziz continuous growth model in the case of mono-atomic approximation. for large undercooling, the change of heat capacity should not he neglected and it usually gives an increase in the interface partition coefficient. Solute trapping may happen at a rather slow growth rate compared with that predicted by other models, because the undercooling and structural relaxation ahead of the S/ L interface lowers the interfacial diffusivity to a great extent. Plase fluctuation has two contending effects, decrease in energy barrier and increase in atomic dragging, therefore exerts dual influences on the partition coefficient.
关键词:
diffuse interface
,
null
,
null
