材料期刊网

INTERFACIAL STRUCTURE AND PHASE REACTION IN SiC/NiCr ALLOY JOINT

J. C. Feng , M. Naka , J. C. Schuster(School of Materials Science and Engineering , Harbin Institute of Technology , Harbin , 150001 , China , Joining and Welding Research Institute , Osaka University , Mihogaoka 11 - 1 , Ibaraki , Osaka 567 , Japan , Institute of Physical Chemistry , University of Vienna , Austria )

金属学报(英文版)

Bonding of SiC to SiC using Ni and Ni - 25at%Cr foils was performed at high temperature.Interface structures and reaction phases were investigated by EPMA analyses and XRD diffraction method, re- spectively. At a bonding temperature of 1273K Ni reacts with SiC and forms various Ni silicides con- taining graphite baside SiC. Ni3Si without graphite was formed at Ni side.The interface structure of SiC/Ni joint was SiC/Ni2Si + C/Ni31 Si12 + G/Ni3 Si/Ni. At the interface between SiC and Ni- 25at%Cr alloy the Ni silicide was only Ni2Si at the same bonding temperature,and further(Cr, Ni)7 (Si, C)3 carbide was formed between Ni silicide + graphite zone and Ni - 25at%Cr alloy.The interface structure of SiC/Ni - 25at%Cr alloy was SiC/Ni2Si + C/(Cr, Ni)7 (Si, C)3+Ni(ss. Cr, Si)/Ni - 25at%Cr.

关键词: interfacial structure , null , null , null

Investigation on Initial Stage of Electroless Deposition on Low Carbon Steel and Pure Iron

Yiyong WU , Yongqian WANG , Yongzhong ZHANG and Mei YAO (School of Materials Science and Technology , Harbin Institute of Technology , Harbin , 150001 , China)Xinguo HU(Applied Chemical Department , Harbin Institute of Technology , Harbin , 150001 , China)

材料科学技术（英）

Initial process is influenced by substrate microstructure according to the study of initial stage of electroless plating on low carbon steel and pure iron. For low carbon steels, depositing on cementite is prior to that on ferrite, and for pure iron, the grain boundaries and some favourable grains are deposited more easily. The initial reactions of electroless depositing of Ni-P alloy have been tentatively proposed

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MICROSTRUCTURE AND COMPRESSIVE PROPERTIES OF NiAl-TiB_2 PARTICULATE COMPOSITES

XING Zhanping* , GUO Jianting , HU Zhuangqi , AN Geying*Institute of Metal Research , Chinese Academy of Sciences , Shenyang , China * Harbin Institute of Technology , Harbin , China

金属学报(英文版)

Ni-50at.%A1 matrix composites containing 0 to 20v.% TiB2 particles have been successfully fabricated by HPES technique. The results show that the Vickers hardness at room temperature and the compressive yield strength from room temperature to 1000℃ of the composites increase with increasing volume fraction of the strengthening phase. Especially, the yield strength of NiAl-20TiB2 was approximately twice as high as that of unreinforced NiAl. The ductility of the composites at room temperature is also superior to the monolithic NiAl.

关键词: intermetallic matrix composite , null , null , null , null

INFLUENCE OF AGING ON MICROSTRUCTURE AND TENSILE BEHAVIOR OF Al ALLOY 8090

JIANG Daming , SUN Fenglian , HONG Bandc , LEI TingquanHarbin Institute of Technology , Harbin , ChinaDOWNHAM D A , LORIMER G WUniversity of Manchester , UK

金属学报(英文版)

The variations of microstructure and tensile behavior of an Al-Li-Cu-Mg-Zr alloy during aging are studied in this paper. It has been found that the fine δ-phase precipitated in the underaging condition and that the δ-, S-and T1-phases precipitate in the peak aging and the overaging conditions. The alloy exhibits transgranular fracture on the underaging condition, and mixture of transgranular and intergranular ruptures in the peak aging and overaging conditions.

关键词: A1 alloy 8090 , null , null , null

Comparison of K_(IC) Values for SiC Whisker Reinforced Ceramic Composites Obtained by Using Various Methods

Tingquan LEI , Guangyong LIN , Shuangxi WANG , and Yu ZHOU (Dept. of Metals and Technology , Harbin Institute of Technology , Harbin , 150001 , China)(To whom correspondence should be addressed)

材料科学技术（英）

The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those obtained by singte edge notched beam (SENB) technique. Experimental results show that the KIC (IM) values calculated with different equations are quite different one from another. For composites without phase transformable components the KIC (IM) and KIC (SENB) values are practically on the same level, but for composites with phase transformable components (partially stabilized zirconia) the KIC (SENB) values are always higher than KIC (IM). This is because that the IM method can not reveal sensitively the toughening effect due to dynamic t-m transformation of ZrO2 as the SENB method does. The accuracy of the IM method depends on the Suitability of the IM equations and was evaluated for the materials used in this investigation. Two new IM equations are suggested with which the KIC (IM ) values can be obtained very close to KIC (SENB) values for composites having phase transformable components.

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The Acoustic Emission Effects of Martensite Transformation in Alloys Cr12MoV and Fe-33Ni-4Ti-10Co

JIAO Chengge , ZHANG Baoqi , WU Gaohui , YAO Zhongkai Harbin Institute of Technology , Harbin , China. Daqing Petroleum College , Anda , China.

材料科学技术（英）

关键词: acoustic emission , null , null

STRUCTURE OF LIQUID Al-Si ALLOYS

GUI Manchang , JIA Jun , SONG Guangchun , LI Peiyong , LI QingchunHarbin Institute of Technology , Harbin , China

金属学报(英文版)

In the light of DSC, electronic microprobe and X-ray diffration analyses of the melt-spinning ribbons and the structures of liquid hypoeutectic Al-7%Si, euteclic Al-12.7%Si and hypereutectic A1-18%Si alloys have been investigated. The results show that the Al-Si clusters in liquid hypoeutectic Al-Si alloy, the Si-Si clusters in liquid eutectic and hypereutectic Al-Si alloys exist at low temperatures, however, the size of clusters decreases gradurally with increasing temperature. This process in which inhomogeneous liquid turns into homogeneous one happens in a range of temperatures.

关键词: Al-Si alloy , null , null

Fracture Analysis of Composites in High-speed Tension

JIANG Chiping , CAO Li , ZOU Zhenzhu , WANG Duo , YAO Zhongkai Harbin Institute of Technology , Harbin , China. To whom correspondence should be addressed.

材料科学技术（英）

In this paper the results of a high-speed tension experiment of the SiC_w/Al composite have been reported and a simplified theoretical model has been developed to study the fracture mechanism of composites in high-speed tension. This theoretical model provides a new explanation for the increase of dynamic fracture strength of composites in high-speed tension.

关键词: composite material , null , null , null

Microstructure and Mechanical Properties of Al-4.9Ni-4.9Ti Alloy Prepared by Mechanical Alloying

Guoxian LIANG , Zhichao LI and Erde WANG (College of Materials Science and Engineering , Harbin Institute of Technology , Harbin , 150001 , China)

材料科学技术（英）

Mechanically alloyed Al-4.9Ni-4.9Ti powders were prepared by milling mixed aluminium, titanium and nickel powders, and then consolidated by hot hydrostatic extrusion. The microstructures of milled powders and extruded bars were characterized by X-ray diffraction and transmission eIectron microscopy observation. The results show that mechanical alloying and consolidating processes have great effects on the microstructures and mechanical properties of extruded materials. Polycrystalline materials having an ultrafine grain size may be prepared by mechanical alloying. The strength and thermal stability are improved with the increasing of processing time of mechanical alloying, since grain size decreases and volume fraction of dispersoids increases as milling time increased

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Microstructure and Mechanical Properties of ZrO_2-Ni Functionally Gradient Material

Jingchuan ZHU , Zhongda YIN and Zhonghong LAI(Dept. of Metals and Technology , Harbin Institute of Technology , Harbin , 150001. China)

材料科学技术（英）

The fabrication. microstructure and mechanical properties of ZrO2-Ni functionally gradient materials (FGM ) have been studied. FGM as well as non-FG M of ZrO2-Ni system was developed by powder metallurgical process. X-ray diffractometer (XRD ). electron probe microanalyzer (EPMA), scanning electron microscope (SEM ) and optical microscope were employed to investigate the crystalline phases. chemical composition and microstructure Experimental results demonstrate that the composition and microstructure of ZrO2-Ni FGM have the expected gradient distribution. There are no distinct interfaces in the FGM due to the gradient change of components. that is, the constituents are continuous in microstructure everywhere. Moreover, Vickers hardness and flexural strength were measured for the common composites as a function of composition. It is made clear that the mechanical properties of the FGM vary corresponding to the constitutional changes as well

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