Papers by Keyword: Cu-Based

Abstract: The shape memory effect,the classification and the principle of shape memory alloys are introduced.The performance features such as melting point,density, resistivity,thermal conductivity, thermal expansion coefficient, phase change heattensile strength fatigue limit, grain size, transition temperature,lag size,one-way shape memory, two-way shape memory of Fe-based,Cu-based and Ti-Ni based shape memory alloys are researched in detail.

Abstract: This paper discusses the effect of several variables in plasma spray method, namely; the flow rate, spray distance and power used on the mechanical properties of Cu-Ni coated A7075. All spraying techniques were designed using 23 factorial plans prior to the actual experiments. The produced coatings were characterised using a scanning electron microscopy (SEM). Morphological observation indicated that most sprayed particles were formed in splash shape splats. The effects of interactions between the response variable factors were screened using a response surface methodology. Three coating factors were used, namely, plasma power, number of coating layer and spraying distance where as the coating hardness and surface roughness were set as the responses. In general, an ideal parameter of 5 coating layers with a power of 30 kW and a spraying distance of 150 mm gave a maximum hardness of 622 Hv and a minimum surface roughness of 9.7 µm.

Abstract: Multifarious fracture features, such as coarse rive-like, micro holes, rugged and flat fracture surface, were systematically investigated in the monolithic Cu46-xZr45Al7Gd2Agx (x=0, 0.5) bulk metallic glasses. The fracture planes presented different angles with the loading direction. These fracture features were completely different from the typical fracture characteristics of amorphous alloys, i.e. vein-pattern and fracturing approximately along the maximum shear stress plane. On the other hand, some tiny strips with about 50 nm intervals were also detected on the flat fracture plane. The preliminary discussions on the formation mechanisms of these exceptional features were presented.

Abstract: The (Cu42Zr42Al8Ag8)100-xSix amorphous alloy rods, x =0 to 1, with 3 mm in diameter were prepared by Cu-mold drop casting method. The glass forming ability, thermal properties and microstructure evolution was studied by differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The XRD result reveals that these as-quenched (Cu42Zr42Al8Ag8)100-xSix alloy rods exhibit a broaden diffraction pattern of amorphous phase. The crystallization temperature and GFA (glass forming ability) of (Cu42Zr42Al8Ag8)100-xSix alloys increase with the silicon additions. The highest Trg (0.59) and γ value (0.405) occurred at the (Cu42Zr42Al8Ag8)99.75Si0.25 and (Cu42Zr42Al8Ag8)99.5Si0.5 alloy. In addition, both of the activation energy of crystallization and the incubation time of isothermal annealing for these (Cu42Zr42Al8Ag8)100-xSix alloys indicates that the (Cu42Zr42Al8Ag8)99.25Si0.75 alloy posses the best thermal stability among the (Cu42Zr42Al8Ag8)100-xSix alloy system.

Abstract: The bulk metallic glass matrix composite comprising Cu54Ni6Zr22Ti18 metallic glass powder and ductile brass powder was fabricated by the warm process. The warm process was carried out by spark plasma sintering, which led to the homogeneous distribution of both phases of brass and metallic glass without pores. The metallic glass matrix composite material exhibits the same crystallization behavior of the metallic glass powder. A compressive strength of 1.0 GPa with a plastic strain of 3 % was obtained in the present metallic glass composite. The composite with enhanced strength and ductility was successfully achieved by introducing a ductile phase in the hard bulk metallic glass.