材料期刊网

INFLUENCE OF EXTRUSION ON DAMPING CAMCITIES OF AS-SPRAY DEPOSITED HIGH SILICON ALLOY ZA27 MODIFIED BY CERIUM

YC. Liu , G.C. Yang , YL. Lu and Z.G. Zhu (State Key Lab. of Solidification Processing , Northwestern Polytechnic University , Xi'an 710072 , China Laboratory of Internal Friction and Defects in Solids , Chinese Academy of Science , Hefei 230031 , China )

金属学报(英文版)

The effects of cerium modification and extrusion on the resultant damping behavior and mechanical properties of the as-sprayed high silicon alloy ZA27 were investigated in an thort to develop a new functional material possessing high damping capacity and good mechanical properties. The damping capacity, as well as the rslative dynamic modulus, was tneasured at frequencies of 1 and 4 Hertz over the 30 to 200℃runge. At below 80℃ the as-sprayed materials appear to be approximately Asquency independent. Above 80℃, the,naterials becotne temperature sensitive, exhibiting the highest damping for the lowest hequency. The extruded, as-sprayed high silicon alloy ZA27 modified by cerium has the highest damping capacity and elongation values among them. The micro8tructure of the as-sprayed high silicon alloy ZA27 modified by 0. 5 wt% cerium was made up of fine lamellar eutectoid, porositg, a light dot-like phase and a polygonal silicon-rich phase. Finally, the opemtive damping tnechanisms were discussed in light of the data obtained hem characterization of microstructure and damping capacity. The high damping capacity was attributed primarily to phase interface thermoelastic damping between the lamellar phases with various substrvctures,except for the grain refinement.

关键词: spray deposition , null , null , null

Structural Phase Transition in Nanostructured TiO_2

Xisheng YE , Jian SHA and Zhengkuan JIAO(Dept. of Physics , Zhejiang University , Hangzhou 310027. China)Zifei PENG and Lide ZHANG(Institute of Solid State Physics , Chinese Academy of Sciences , Hefei 230031 , China)

材料科学技术（英）

Using DTA (difFerential thermal analysis) measurement on nanostructured TiO2, we find two endothermic peaks on the DTA curve. From XRD (X-ray diffraction) analysis of the original nanostructured TiO2 and its heat-treated samples, we obtain the following results: the first endothermic peak corresponds to the desorption of physical or chemical absorption, the second one is related to the structural phase transition from brookite to anatase then to rutile, and this structural phase transition is beneficial to the grain growth of nanocrystal

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Characterization of Nanocrystalline Intermetallic Compound NiAl Synthesized by Condensation

Yong QIN , Xiaoying QIN and Lide ZHANG (Institute of Solid State Physics , Chinese Academy of Sciences , Hefei 230031 , China)(To whom correspondence should be addressed)

材料科学技术（英）

Nanocrystalline intermetallic compound NiAl was Synthesized by evaporating NiAl master alloy in inert-gas followed by in situ compaction, and its structure was studied by means of X-ray diffractometry and transmission electron microscope. Experimental results reveal that the assynthesized nanocrystalline sample has a mean grain size of less than 10 nm and it is dominantly composed of the cubic structure phase NiAl. However, nanocrystalline Ni3Al as a trace phase mixed in NiAl phase, was also detected by transmission electron microscope observation.

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Conceptual design of Hefei advanced light source

中国物理C

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Conceptual design of Hefei Advanced Light Source(HALS)injection system

中国物理C

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Controversy about the Origin of the Grain Boundary Internal Friction Peak and Its Clarification

T.S.Ke (Tingsui GE)(Lab. of Internal Friction and Defects in Solids , Institute of Solid State Physics , Chinese Academy of Sciences , Hefei 230031 , China)

材料科学技术（英）

In the seventies some scientific workers from France and ltaly suggested that the grain boundary internal friction peak (named the Ke peak in the literature) widely accepted as a grain bound ary process, is originated from the motion of lattice dislocations. Since this problem is one of fundamental importance, this controversy has drawn much international attention. Started from 1982, the Hefei research group made a critical analysis of the large amount of literature concerning this problem and performed a series of crucial experiments to clarify the controversy It is concluded that the irrelevant evidence suggested by the controverters comes from the farfetched interpretation and the mis-identification of the internal friction peaks appeared under various experimental conditions and different states of the specimens.

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