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A Near-bulk Quasicrystal Alloy Formed in Zn-Mg-Y System

Yali TANG , Ningfu SHEN , Xiaofang LIU(Research Center for Materials , ZhengZhou University of Technology , Zhengzhou 450002 , China)Zhiping LUO(Institute of Aeronautical Materials , Beijng 100095 , China)Baicheng LIU(Tsinghua University , Beijing 100084 , China)

材料科学技术（英）

Zn-Mg-Y and Mg-Zn-Y-Zr ingots with different chemical compositions were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The icosahedral phases were found in all alloys studied in present work under the as-cast conditions. There are nearly all quasicrystal phases with some MgZn2 Laves phase in a Zn-28.31Mg-13.80Y alloy (wt pct).After annealing at 400℃ for 8 h, the quasicrystal phases transformed to an fcc "W" phase in an Mg-5.57Zn-1.08Y-0.60Zr alloy (wt pct).

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Microstructural Characteristics and Stability in a Rapidly Solidified Al-Fe-Nb-Si Alloy

Shaokang GUAN and Ningfu SHEN(Dept. of Materials Science and Engineering , Zhengzhou University of Technology , Zhengzhou 450002 , China) Yulin GONG(Central China Petroleum and Natural Gas Development Corporation of Henan Province , Zhengzhou 450002 , China)Ha

材料科学技术（英）

The microstructure and stability in a rapidly solidified Al-Fe-Nb-Si alloy were studied by using transmission electron microscopy (TEM) with energy dispersive X-ray spectrometry (EDXS) and X-ray difFraction technique. It is shown that the addition of Nb to Al-Fe-Si alloy may increase undercooling of melt, and form the featureless zone structure, the size of the intercellular phases and the distance betWeen intercellulars of Al-Fe-Nb-Si alloy are two times smaller than that of Al-Fe-V-Si alloy under the same conditions. Further, the microstructure of the featureIess zone has the better thermal stability after annealing at 623 K for 24 h.

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Laboratory Assessment of Lubricants for Wheel/Rail Lubrication

Xingzhong ZHAO , Jiajun LIU and Baoliang ZHU (Tsinghua University , Beiing 100084 , China)Cuiyuen WANG (Zhengzhou Research Institute of Mechanical Engineering , Zhengzhou 450002 , China)

材料科学技术（英）

The antiwear properties of two wheel/rail lubricating oils were tested and compared on an Amsler machine. Under same testing conditions, oil A (developed by authors) showed much better wear resistance and higher load-carrying capacity than oil B (imported from abroad). The X-ray diffraction (XRD) analyses of the worn surfaces showed that different extreme pressure (EP) lubricating films were formed on the surfaces when the rollers were lubricated with different oils under boundary Iubrication condition. The EP film of oil A was a composite film containing three compounds, FeO, FeSx and FeP, while oil B formed only a simple EP film of FePO4. The composite EP film showed lower shear strength and better antiwear property than the simple EP film,which brought about different wear resistance of the two wheel/rail lubricating oils.

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A DEVELOPMENT STUDY OF CAST COPPER ALLOY WITH HIGH STRENGTH AND HEAT-RESISTANCE

WANG Zheng , REN Chenxing and WANG Suying(Department of Materials Science , Zhengzhou Institute of Technology , Zhengzhou 450002 , China)Manuscript received 2 January 1996 , in revised form 7 March 1996)

金属学报(英文版)

By means of Precipitation hardening, a cast copper alloy with high strength and heatresistance named Cu-6Ti-Cr-Al has been developed. This alloy has good castability. After water quenching at 860℃ for 1 h and aging at 450℃ for 4 h, the tensile strength, σ_b, is greater than 890MPa and the compressive strength, σ_(bc), reaches 1300MPa, while the ratio of compression, ε_c, is maintained at 20%. When the environmental temperature is raised to 450℃, the mechanical properties do not show any appreciable loss. These copper alloy castings have been used on the roll sleeves of rubber formers and the journal bearings of sheet mills. The results have shown that the service life of these parts is much longer than that of aluminium bronze and 904alloy castings. In the present work, the microstructure, mechanical properties and strengthening mechanism were investigated.

关键词: : cast copper alloy , null , null , null

ACTIVATION MECHANISM OF AMORPHOUS Ni_(63)Zr_(32)La_5 ALLOY HYDROGENATION CATALYST

X.K. Wang. N. F. Shen and G.J Lei(Dept. of Materials Science and Engineering , Zhengzhou Institute of Technology , Zhengzhou 450002 , China)H. C. Gu(Dept. of Materials Science and Engineering. Xi'an Jiaotong University , Xi'an 710049 , China Manuscript received 27 September 1995)

金属学报(英文版)

The catalytic activity of amorphous Ni_63 Zr_32 La_5 ribbon for hydrogenation of ethyne to ethylene can be greatly enhanced when the alloy ribbon is pretreated with dilute acid solution,heated under negative atmosphere pressure and subjected to hydrogen reduction successively. The change of surface state of the ribbon during the activation has been analysed by AES and XPS. The surface of as-received ribbon is covered with a thin film of La_2 O_3. After pretreatment. the surface concentrations of both Ni and Zr increase obviously, whereas the surface concentration of La decreases markedly.Finally, on the surface of activated catalyst the Ni and NiO disperse finely on the matrix consisting of oxides of both Zr and La and a small amount of fluorides of Zr and La.

关键词: :amorphous Ni_(63) Zr_(32) La_5 alloy;catalyst;activation mechanism

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