材料期刊网

SYNTHESIS OF TiN BY MICROWAVE CARBOTHERMAL REDUCTION OF TiO_2

B.H Liu , Y Zhang , S.X. Ouyang , and H.C. Gu (Research Institute of Technical Chemical Physics , East China University of Science and Technology , Shanghai 200237 , China)(Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China)(State Key Laboratory for Synthesis and Processing of Advanced Materials , Wuhan University of Technology , Wuhan 430070 , China)

金属学报(英文版)

Titanium nitride powder was synthesized by microwave carbothermal reduction of titanium oxide. The mechanism and thermal dynamics of the reaction process were studied. The results show that the microwave carbothermal reduction technology has unique advantages over the conventional reduction methods. It can not only lower the reaction temperature, shorten the synthesis cycle, but also refine the product particles,as well as improving the reactivity of the powder.

关键词: TiN microwave , null

University of Science and Technology Beijing

JIA Shizhen University of Science and Technology Beijing , China.

材料科学技术（英文）

关键词:

HARDENING OF L1_2-ORDERED Co_3Ti BY PRECIPITATION OF FCC-Co PHASE

W. H. Tian , S.L. Hu and M. Nemoto(Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Forming , University of Science and Technology Beijing , Beijing 100083 , China)(Department of Materials Science and Engineering , Faculty of Engineering , Kyushu University , Fukuoka 812 , Japan)

金属学报(英文版)

The Co3 Ti phase hardens appreciably by the fine precipitation of disordered fcc Co-rich phase upon aging after quenching from solution annealing temperature. Transmission electron microscope (TEM)observations revealed that the precipitates are platelet in shape, lying nearly parallel to the {100} planes of the L12-ordered matrix, and perfectly coherent with the matrix lattice at the beginning of aging. The high temperature strength increases appreciably with the fine precipitation of disondered Co-rich phase over the whole temperature range investigated. TEM observations of the deformed alloys after underaging revealed that saperdislocations are pinned by precipitates indicating an attractive interaction between dislocations and precipitates.

关键词: Co_3 Ti , null , null , null , null

EFFECT OF Cr ADDITION ON MICROSTRVCTURES AND MECHANICAL PROPERLIES OF β-NiAl ALLOYS

W.H. Tian , S.L. Hu and M. Nemoto(1) Department of Materials Physics , University of Science and Technology Beijing , Beijing 100083 , China 2) Department of Materials Forming , University of Science and Technology Beijing , Beijing 100083 , China 3) Department of Materials Science and Engineering , Faculty of Engineering , Kyushu University , Fukuoka 812 , Japan)Manuscript received in revised form 12 October 1998

金属学报(英文版)

The effect of Cr addition on the microstructures and mechanical properties of NiAl inermetallic alloys containing 4 to 8 mol% Cr has been characterized. It is shown that Cr is not only an efficient soild solution strengthener in NiAl, it is also an efficient precipitation Strengthener by fine dispersion of α-Cr particles. Transmission electron microscope observations have revealed that fine spherical particles of α-Cr appeared homogeneously in the NiAl matrix by aging at temperatures around 1073K after solution annealing at 1563K. The aging behavior was investigated by microhardness measurements and the temperature dependence of the yield stress of NiAl containing α-Cr particles was investigated by compression tests over the tempemture range from 298 to 1173K. NiAl alloys happened appreciably by the precipitation of α-Cr particles.Dislocations bypass the particles during deformation and typical Orowan loops were observed surrounding the α-Cr particles after deformation. Although the dispersion Of α-Cr particles increases the yield strength of NiAl at intermediate temperutre, the strength decreases appreciably at higher temperatures.

关键词: NiAl , null , null , null , null

SOLUBILITY OF NITROGEN IN MOLTEN GRAY CAST IRON

ZHAI Qijie , HU Hanqi , University of Science and Technology Beijing , Beijing , China HU Hanqi , Professor , Faculty of Foundry , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

The expressions of the dependence of nitrogen solubility in molten gray cast iron on the temperature and composition of the melt were proposed under the condition of foundry practice. Three gray cast iron specimens with different compositions were examined in good agreement with the derived expression.

关键词: gray cast iron , null , null

Abstracts of papers from Journal of University of Science and Technology Beijing

稀有金属（英文版）

关键词:

MAGNETIC PROPERTIES AND STRUCTURES OF NANO-CRYSTALLINE Fe-P-C-Mo-Cu-Si ALLOYS

Y.F. Gao , J.Tan , G.D. Liu , C.L.Zhang , T.Liuand R.Z Ma (Rapidly Quenched Materials Research and Development Centre , Central Iron & Steel Research Institute , Beijing 100081 , China)(Metal Physics Department , University of Science and Technology Beijing , Beijing 100083 , China)

金属学报(英文版)

A mostly single bcc phase with grain sizes of 15-20 nm was prepared by crystallization of amorphous Fe-P-C-Mo-Cu-Si alloys.The Bs value (H=10000 Oe) reaches 1.595 T for Fe(79.5) P(12)C6Cu(0.5)Mo(0.5)Si(1.5) alloys. The low core loss of 0.14 w/kg at 1.3 T and 50 Hz was confirmed for the bcc Fe(79.5)P(12)C6Cu(0.5)Mo(0.5)Si(1.5) alloy.The structures of the alloy annealed at different temperatures have been investigated by means of Xray diffraction and transmission electron microscope. The relationship between the structure and magnetic properties of the alloy is discussed.

关键词: : amorphous alloy , null , null

EFFECT OF INTERPHASE LIFT FORCE ON THE FLUID FLOW IN AN AIR-STIRRED CYLINDRICAL VESSEL

L.F. Zhang , K.K. Cai , Y. Qu and Y.S. Shen Postdoctoral Fellow of Japan Science Promotion Society Taniguchi Lab. , Department of Metallurgy , Graduate School of Engineering , Tohoku University , Sendai980-8579 , Japan School of Metallurgy , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.

关键词: two-phase Eulerian model , null , null , null

CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词: stress corrosion cracking , null , null , null

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALE PARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

Z. Bian , G. He and G.L. Chen (State Key Laboratory for Advanced Metals and Materials , University of Science and Technology Beijing , Beijing 100083 , China) J. Lu , D.J. Chen , G.C. Tu , G.J. Chen and X.J. Hu (Shougang Metallurgical Research Institute , Beijing 100085 , China)

金属学报(英文版)

Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystallization kinetics of Al80Ni6 Y8 Co4 Cu2 amorphous alloy shows that the precipitation of α-Al particles is the growth process controlled by diffusion of the solute elements rejected from the growing crystals. By quenching at different cooling rates, a mixed structure consisting of nanoscale α-Al particles and the remaining glass matrix or structure consisting of nanoscale particle (Al phase or Al3Ni compound) with a size of about 100nm was formed. The addition of Co elements and Cu elements to Al-Ni-Y alloy systems increases the glass formation ability of the alloy and the thermal stability of the supercooled liquid region against crystallization, which results from significant difference of atomic size, strong bonding nature among constituent elements and the low diffisivity of the solute elements due to the concentration gradient in the growing front of crystals.

关键词: a mixed structure , null , null , null , null , null , null