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Quasicrystalline Phase in As-cast Mg-Zn-Y-Zr Alloy

Yali TANG , Ningfu SHEN and Xin YUAN (Research Center for Materials , Zhengzhou Institute of Technology , Zhengzhou , 450002 , China)Zhiping LUO and Shaoqing ZHANG (Institute of Aeronautical Materials , Beijing , 100095 , China)(To whom correspondence should be ad

材料科学技术（英文）

An icosahedral phase in as-cast Mg 5. 78Zn-0.89Y-0.48Zr (wt-%) alloy has been identified with transmission electron microscope (TPM) The selected area diffraction patterns (SADP) from the phase show a five-fold symmetry of a quasicrystalline structure. The energy dispersive X-ray spectra (EDXS) indicate that the quaternary phase has a chemical composition of 67.6Zn-1 9.4Mg-8,1 Y-4 9Zr in at -%

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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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