材料期刊网

SCALING PROPERTIES OF INTERFACES IN CRYSTALS UNDER NONEQUILIBRIUM CONDITIONS

D. W Shi , J. Y Huang and Q. W Long(International Centre for Materials Physics , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China Laboratory of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , ChinaState Key Laboratory for Fatigue and Fracture of Materials , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China )

金属学报(英文版)

We proposed an equation of Langevin type to describe the interface evolution in crystals under nonequilibrium conditions(such as in Cu-Fe or Cu-Co system upon ball miling). The scaling property (H) of this equation is in good agreement with the Monte Carlo simulations decribed by Bellon and Averback. In this equation the volume dchsion and intedece diffusion are all important and this is consistent with some experimental results.

关键词: scaling , null , null , null

THE EFFECT OF SILICON ADDITIVE ON THE STRUCTURE AND PROPERTIES OF C-B_4C-SiC COMPOSITE

HUANG Qizhong , YANG Qzaoqin and WU Lijun(Powder Metallurgy Research institute , Central Sonth University of Technology , Changsha 410083 , China Materials Research and Test Center , Hnnan University , Changsha 410082 , ChinaLab. of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Sciences , Shenyang110015 , ChinaState Key Laboratory for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)Manuscript received 4 August 1995 , in revised form 6 April 1996

金属学报(英文版)

A Preliminary study of the effect of silicon additive on the structure and properites of C-B_4C-SiC composite was conducted. A liquid Phase has formed and the liquid Si reacts with C to form SiC at the grain boundary when sintering, which accelerates the sintering process and retards the grain growth. Consequently, the density and strength of the composite increase markedly. And the increase in the density increases the oxidation resistance and decreases the specific resistance of the composite. Furthermore,the C-B_4 C-SiC composite has good heat-shock resistance. The phenomena may be dueto the strengthening and toughening of microcracks.

关键词: :Si additive , null , null

MAGNETOSTRICTIVE BEHAVIOUR OF R(Fe_(1-x)Al_x)_y ALLOYS(R = Dy_(0.65)Tb_(0.25)Pr_(0.1))

WANG Bowen , WU Changheng , ZHUANG Yuzhi , JIN Ximei , LI Jingyuan(Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)(Shenyang Institute of Technology , Shenyang 110023 , China)(Institute of Physics , Chinese Academy of Sciences , Beijing 100080 , China)

金属学报(英文版)

The structure and magnetostriction of R(Fe_(1-x)Al_x)_y alloys(R=Dy_(0.65)Tb_(0.25)Pr_(0.1),x≤0.3,y=1.8 and 2) have been investigated using metallography, X-ray diffraction, electron probe micro- analysis(EPMA) and standard strain gauge techniques.It was found that the matrix of R(Fe_(1-x)Al_x)_2 alloys is cubic Laves phase(Dy,Tb,Pr)(Fe,Al)_2 and the second phase is PuNi3-type (Dy,Tb,Pr)(Fe,Al)_3 when x<0.15.The R(Fe_(1-x)Al_x)_(1.8) alloys contain trace of rare earth-rich phase.The magnetostriction of R(Fe_(1-x)Al_x)_y alloys decreases with increasing x in high magnetic fields; however, it exhibits a peak when x = 0.05 in low magnetic fields(H≤ 160 kA / m).The magnetostriction of R(Fe_(1-x)Al_x)_(1.8) alloys is higher than that of R(Fe_(1-x)Al_x)_2 alloys when x<0.15.

关键词: :rare earth-iron alloy , null , null

HREM STUDY OF GRAIN BOUNDARY PHASES IN Fe-Ni-Co-Nb-Ti SUPERALLOY

R.M. Wang , C.Z. Li , S. W. Zhang and M.G.Yan(1)Institute of Aeronautical Materials , Beijing 100095 , China 2)Laboratory of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China 3)Beijing Laboratory of Electron Microscopy , Chinese Academy of Sciences , Beijing 100080 , China Manuscript received 26 August 1996)

金属学报(英文版)

The microstructures of the grain boundary phases in Fe-Ni-Co-Nb-Ti superalloy have been studied by high resolution electron microscopy (HREM).Besides the Laves phase,three other grain boundary phases have been found and analyzed. The ε phase particles are needle-like with some stacking faults along the(0001) direction. The dominant phase at the grain boundaries is the orthorhombic phase that is also rod-like. High reselution image also confirms the existence of the triclinic phase at the grain boundaries that is irregular and scarce.

关键词: :high resolution electron microscopy , null , null

Guangzhou Institute of Energy Conversion,The Chinese Academy of Sciences,Guangzhou 510070,China

B.W. Wang , H. Shen

金属学报(英文版)

Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.

关键词: solar selective thin film , null , null , null

ANALYSIS OF FLUID FIELD OF LIQUID METAL IN ELECTROMAGNETIC CENTRIFUGAL CASTING

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

EFFECT OF Ti-ADDITION ON MECHANICAL ALLOYING OF NiAl

LIU Zhiguang+ * , GUO Jianting * , LI Gusong+ , HU Zhuangqi++State Key Lab. of RSA , Institute of Metal Research , Chinese Academy of Sciences , Shenyang , China * Institute of Metal Research , Chinese Academy of Sciences , Shenyang , China

金属学报(英文版)

Mechanical alloying (MA) of Ni50Al45Ti5 (atomic per cent) is studied by in situ thermal analyses, XRD and metallography. The results showed that the alloying process of Ni50Al45Ti5 is similar to that of Ni50Al50. The addition of 5 at.%Ti prolongs the milling time of alloy prior to the explosive reaction in the alloy. The final product is nanocrystalline β-phase NiAl(Ti) (B2 structure). The addition of 5 at.% Ti shows little effect on the lattice parameter of β-phase.

关键词: mechanical alloying , null , null , null

EFFECT OF CHROMIUM AND BORON ON ENVIRONMENTAL EMBRITTLEMENT OF FORGED Fe3Al

J.Q. Su , S.J Gao , and Z.Q. Hu (Liaoning Key Laboratory for Materials and Hydrogen , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)(National Key Laboratory for RSA , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

The effects of addition of chromium or boron on room temperature tensile properties,fracture behavior and susceptibility to test environments (air vs. vacuuwi of forged Fe3Al have been investigated. The results indicated that both chromium and boron result in increasing room temperuture ductility and fracture strength of the Fe3Al alloy whether tested in air or in vacuum. The susceptibility to test envimnment was described with the embrittlement index I: I=(δv-δA)/δv. The embrittlement indexes, for Fe-30Al, Fe-30Al-4Cr and Fe-30Al-0. 13B (at. %), are 24%, 37% and 29%,respectively. Scanning electron microscope examination of fracture surface revealed that the fracture mode of the three alloys remains unchanged, and all of them exhibited a transgranular cleavage fracture mode when tested in vacuum or air.

关键词: chromium , null , null , null

INVESTIGATION ON THE FORMATION MECHANISM OF TITANIUM CARBIDE PREPARED BY IN SITU REACTION IN MOLTEN ALUMINUM

B. Yang , Y.Q. Wang , J. Zhang and B.L. Zhou(Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)(Nanchang University , Nanchang 330029 , China)(International Center for Materials Physics , Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

A novel technique m which TiC particulates are prepared by an in situ reaction in molten aluminum is introduced for producing TiC/Al composite. In order to reveal the characteristic of the technique, the formation mechanism of TiC particulates prepared by this method is studied in this paper. Both theoretical and experimental results have shown that the TiC particulates are formed by a diffusion mechanism when the molar fraction of aluminum in the preforms is higher than 20.02%. On the contrary, the TiC particulates are formed by a solution-precipitation mechanism when the fraction of aluminum in the preforms is lower than 20.02%.

关键词: in situ reaction , null , null

The Abstracts of Papers in Special Issue on the Seventh Five Year Project for Rare Earths of Chinese Academy of Sciences(in Chinese)

熊炳昆

中国稀土学报

关键词: