Papers by Author: Shu Qing Yan

Abstract: The microstructures characteristics of interface and wear resistance Of ZnAl27 composite reinforced by SiC particles have been studied by means of SEM and HRTEM. The results shown that SiC particles could be distributed in ZnAl27 alloy uniformly, and the excellent combined interface between SiC particles and ZA27 matrix is formed. CuZn4 could nucleate on SiC particles and grow up at higher speed along SiC particles than at the vertical direction. The wear resistance of the ZnAl27 alloy could be increased remarkably due to the addition of SiC particles. When the SiC particles are added to 30％, the wear resistance was raised by 126.5 times

Abstract: In this study, some low-titanium aluminum alloys produced by electrolysis were prepared and the effect of various titanium contents on microstructure and tensile property of Zn-Al alloy was investigated. The test results showed that addition of titanium by electrolysis is an effective way to refine the grain size of Zn-Al alloy. As the titanium content is 0.04 wt%, the grain size becomes to be a minimum value and the tensile property of the alloy reaches to the maximum. Electrolysis showed that titanium atoms are to be some inherent particles in low-titanium aluminum alloy. These titanium atoms enter into the aluminum melt liquid and spread to the whole melt rapidly under stirring action of electromagnetic field of the electric current. The heterogeneous phase nuclei are high melting TiC and TiAl3 particles formed from in-situ precipitating trace C and Ti during cooling process. These in-situ precipitating heterogeneous nucleation sites with small dimension, high dispersity, cleaning interface and fine soakage with melt, have better capacity of heterogeneous nucleation than of exotic particles. It may inhibit grain growth faster and more effective in pinning dislocations, grain boundaries or sub-boundaries.

Abstract: In the present work, rapidly solidified alloys strips with Al-0.24Ti and Al-21Si-0.24Ti(in wt.%) were prepared by single roller melt-spinning method. The microstructures, phase and morphology characteristics of the resultant strips were characterized by means of scanning electron microscopy (SEM),transmission electric microscopy (TEM) and XRD technique. The results show that the grains have been refined after rapid solidification processing, and the micro-nanocrystalline grain are formed. The morphology characteristics can be changed. The microstructures of Al-0.24Ti alloys strip are micro-nanostructure α-Al solid solutions which are similar with granular or nodular, the corresponding SAD pattern is rings, it presents characteristic of polycrystal; Compared with equilibrium solidification, the microstructures of hypereutectic Al-Si alloy are changed obviously. They are composed of primary micro-nanostructure α-Al supersaturated solid solution and nanocrystal granular (α+Si) eutectic which set in the supersaturated solid solution. The nucleation and growth of primary silicon are suppressed and primary silicon can not precipitate, meanwhile, α-Al phase is nucleated which prior to eutectic, therefore the microstructures become into the metastable state. The mechanism of the formation for microstructures of melt-spinning alloys has also been discussed.