Papers by Author: Hong Wei Cui

Abstract: The microstructure of magnesium alloy sheets (nominal composition Mg–6Zn–Y in at. %) was investigated with the Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) technique after the annealing treatment. Tensile test at room temperature was performed to show the influence of annealing treatment on mechanical properties. Experimental results indicate that there are a large number of twin crystals appearing in microstructure of the extruded Mg-Zn-Y alloy sheet at 350 °C. The distinct icosahedral phase appears on the α-Mg matrix in granular form and the strength gets largely improved to the maximum. The uniform distribution of isometric crystal contributes to the best elongation at the annealing temperature of 400 °C.

Abstract: Equal channel angular pressing (ECAP) has been conducted on as-extruded Mg-Zn-Y alloy containing quasicrystal phase at a temperature of 523 K. The optical images indicate that after 8 ECAP passes through route BA, the grain size of the extruded alloy is decreased sharply; and the coarse eutectic icosahedral quasicrystal phases (I- phases) are broken and dispersed in the alloy; and the distributions of Zn and Y elements become more homogeneous. These can be attributed to the shear effect during the ECAP processing. TEM micrographs show the grain refinement, the evolution of broken and dispersed I- phases and dispersion precipitation of nano I-phases during 1- ,4- and 8- pass ECAPed Mg-Zn-Y alloy. And the mechanism of grain refinement is also discussed.