Papers by Author: Rong Xi Yi

Abstract: Cu-4% mixed-powder consisting of rough copper powder and graphite powder was separately mechanical alloyed by high-energy ball milling. The phases and micrograph of these powders were determined by X-ray diffraction and scanning electron microscopy (SEM). The results show an increase in the lattice parameter of copper with milling times, up to a saturation value of about 24h; There was an absence of graphite reflections from X-ray diffractograms after longer milling times.

Abstract: This paper aims to study the effects of rare earth Cerium addition on mobility, solidification shrinkage, casting microstructure and hot tearing tendency of Al-4.5Cu alloy. Results show that by adding appropriate rare earth Cerium into the Al-4.5Cu alloy, the viscosity of liquid metals can be reduced, the mobility of alloy can be increased, and the shrinkage during the solidification of liquid metal can be reduced. Further more, as the tendency of alloy dendrite is inhibited and the microstructure of the casting alloy is improved, the alloy can be purified, its thermal conductivity can be enhanced, and the hot tearing tendency of it can be decreased remarkably. It proves that when rare earth Ceriumaddition in Al-4.5Cu alloy is 4w%, the mobility of Al-4.5Cu alloy will be the maximum, and its volume shrinkage will be the least. Meanwhile, the grains of alloy are refined and round. The alloy also shows the lowest hot tearing tendency.

Abstract: A new technique using slope vibration casting process during heating and isothermal holding period to prepare Al-7Si-2RE alloy has been studied. The small, near-spherical and non-dendritic microstructure with the semi-solid processing requirements has been obtained. Experiments show that the cooling method, pouring process and the convection of melt caused by slope vibration had significant effects on the formation of near-spherical primary gains. The water-cooled copper mold casting with slope vibration at the temperature near liquidus can obtain Al-7Si-2RE alloy with small homogeneous equiaxed grains, the average grain diameter is 48.3μm, and the average grain roundness is 1.92.