材料期刊网

Wettability of Ni-base Reactive Brazing Alloys on Alumina

Chuangeng WAN(Welding Division , Dept. of Materials Engineering , Jilin University of Technology , Changchun , 130025 , China)Polyvios Kritsalis and Nicolas Eustathopoulos(Lab. de Thermodynamique et Physico-Chimie Metallurgiques , ENSEEG , Institut National Pol

材料科学技术（英文）

The influences of the additions of Ti or / and Si on the wettability of Ni-base alloys on alumina were investigated with the sessile drop method. The interfacial chemical reaction products were analyzed by scanning etectron rnicroscope and microprobe. Their effects on the wettability and the affecting factors for them to be produced were discussed. A new Ni-base braze alloy (NiFeCr10Si15Ti) was designed for brazing alumina with the superior qualities such as low contact angle (less than 25 degrees), high work temperature (near 1073 K) and good resistance to oxidations, etc.

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Size-dependent Initial Sintering Temperature of Ultrafine Particles

Qing JIANG(Dept. Materials Science and Engineering , Jilin University of Technology , Changchun 130025 , China)Frank G.Shi(School of Engineering , University of California , Irvine , CA 92697-2575 , USA)

材料科学技术（英文）

A model for the size-dependent initial sintering temperature of ultrafine particles was established. The theoretical predictions for the size-dependent sintering temperatures of W, Ni and Ag ultrafine particles are consistent with available experimental evidence

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Influence of Ti on MC Carbide in M2 Steel

Yanjun LI(Shcool of Materials Science and Engineering , Harbin Institute of Technology , Harbin 150001 , China)Qichuan JIANG , Yuguang ZHAO and Zhenming HE(Dept. of Metallic Materials , Jilin University of Technology , Changchun 130025 , China)

材料科学技术（英文）

Influence of Ti on MC carbide of M2 high speed Steel was investigated by experimental observation, thermodynamic calculation and crystallographic calculation. With addition of Ti into M2 steel, large quantities of dispersed TiC particles formed in the steel melt at higher temperature than that of the formation of MC carbide. TiC can act as heterogeneous nuclei for the crystallization of MC carbide particles, and therefore promote the formation of blocky MC carbide.

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Institute of Materials Science at Jilin University——A Brief Overview

WANG Yuming Institute of Materials Science , Jilin University , Changchun , 130023 , China

材料科学技术（英文）

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A Theoretical Study of the Pressure for Liquid Metal Infiltration of a Fiber Preform

Sirong YU and Zhenming HE(Dept. of Metallic Materials Engineering , Jilin University of Technology , Changchun , 130025 , China)

材料科学技术（英文）

A theoretical model has been established for calculating the infiltration pressure of metal melt into the preform of ceramic fibers according to the basic principle of hydromechanics. There are three forces acting on the infiltration process in the model, i.e. viscous friction, capillary force, and gravity The effects of the volume fraction of fibers (Vf) and infiltrating depth on the infiltration pressure are discussed. The results show that the infiltration pressure increases with the increase of fiber volume fraction and infiltration depth. There is a linear relationship between infiltration pressure and infiltiation depth. The effect of gravity on the infiltration pressure can be ignored

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EFFECT OF MODIFICATION ON CARBIDE GRANULATION AND ITS MECHANISM

S.Q. Wang , Q.C. Jiang , X.H. Cui and Z.M. He(School of Materials Science and Engineering , Jilin University of Technology , Changchun 130025 , China) Manuscript received in revised form 15 September 1998

金属学报(英文版)

By the modification, network carbide was disconnected at 1100℃ through uneven dissolution at higher energy places in carbide, where there is twin or lattice distortion,and granulated at 1130℃ through element diffusion. The stability of M7C3 carbide was decreased owing to the modification reducing the segregations of Cr and M0, thus the temperature, at which uneven dissolution of carbide commenced, was decreased. Also lattice distortion or defect such as twin in carbide was increased by the modification, which prompted widespread disconnections in carbide. In addition, the modification prompted element diffusion to accelerate the kinetics process of carbide granulation.

关键词: ledeburite steel , null , null , null

CALORIMETRY OF PARTIAL MARTENSITIC TRANSFORMATIONS

LI Jianchen , NAN Shenghui and JIANG Qing.(Department of Materials Science and Engineering , Jilin University of Technology , Changchun 130025 , China)Manuscript received 20 Angust 1995 , in revised form 7 April 1996

金属学报(英文版)

Partial thermoelastic martensitic transformations have been studied by calorimetry on CuAlNi single crystals with special methods. The chemical enthalpy change, the elastic energy stored at the interfaces or inside of the martensite and the energy dissipated in acoustic emission were calculated for a partial transformation; the relationship among them was studied based on measured latent heat and transformation temperatures. The influence of specimen shape on the stored elastic energy was evaluated and discussed.

关键词: : partial martensitic transformation , null , null , null

Wettability of CuNi-Ti Alloys on Si_3N_4 and Interfacial Reaction Products

Chuangeng WAN , Huaping XIONG and Zhenfeng ZHOU (Dept. of Materials Science and Engineering , Jilin University of Technology , Changchun 130025 , China)(To whom correspondence should be addressed)

材料科学技术（英文）

Based on the alloy Cu55Ni45 (at pct), holding the proportion of Cu to Ni in constant and in the temperature range of 1233~1573 K, the wetting angles of CuNi-0~56 at pct Ti alloys on Si3N4 have been measured by the sessile drop method. With the increase of Ti content, the wetting angles decreased. The equilibrium wetting angle was 5° when Ti content ≥32 at pct.In the case of same Ti content, the activity of Ti in CuNiTi alloy was weaker than that in CuTi alloy The cross-section of the CuNiTi-Si3N4 interface and the elements distribution were examined by scanning electron microscope with X-ray wave-dispersion spectrometer, and the reaction products formed at the interface were determined by X-ray diffiaction analysis method.

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Effect of Si, Al and Bi on Structure and Properties of As-welded and Austempered Ductile Iron Weld Metals during Gas Welding

Daqian SUN , Zhenfeng ZHOU and Haicheng CAO (Dept. of Mater. Sci. Eng. , Jilin University of Technology , Changchun 130022 , China)

材料科学技术（英文）

Effect of Si, Al and Bi on the microstructure and mechanical properties of as-welded and austempered ductile iron weld metals has been studied with SEM, TEM, X-ray diffraction, image analysing system, tension and other test methods. Results show that increasing weld Si, Al and Bi content favours improving the chilling tendency of as-welded ductile iron weld and mechanical properties of austempered ductile iron weld and the mechanism is also discussed. On this basis the optimum chemical composition of weld is determined. The mechanical properties of weld and welded joint after austempering can match those of austempered ductile iron

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Packing Densities and Glass Forming Ability of Alloys

Qing JIANG , Xiaoya XU , Hongjun NIU and Xiaoxia LU(Dept. of Materials Science and Engineering , Jilin University of Technology , Changchun 130025 , China)

材料科学技术（英文）

The random closed packing fraction of hard balls of three different sizes were measured by use of the Archimedes method. This packing fraction increases as the kind of balls with different sizes increases. The packing fraction is related to the mixing entropy of an ideal solution in respect to the holes among the hard balls. The composition zone of La-Al-Ni amorphous alloy made by cooling the alloy melt with a cooling rate of 90 Ks-1 is located at same zone of the largest values of packing fraction and mixing entropy of hard balls in the ternary system. where the proportion of atom sizes of La, Al and Ni is similar to that of hard balls. The packing fraction and the mixing entropy are qualitatively considered as one of the criteria of the glass forming ability of alloys

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