It is well known that the ductility of magnesium and magnesium alloy is too poor to be processed. After normal hot extrusion, the ductility of magnesium alloy will be improved, but not noticeably. In this paper, further extrusion (Extrusion Ratio is 6.25) is adopted to commercial AZ31 magnesium alloy rods (Extrusion Ratio is 2) at different temperatures in order to refine the size of grain, then the rods with the crystallite size between 4-10μm is obtained, and the influence of crystallite with different grain size on the ductility of this alloy is investigated further. A lot of experiments and research indicate that: the elongation of the initial billet with the grain size of 30μ m can reach about 12%; after extrusion at different temperatures, the grain size can be refined to below 10μm, and the ductility goes up to 24%-30%. It also shows that, when the grain size of AZ31 magnesium alloy is below 10μm, the ductility is effected obviously. Only when the grain size is about a few microns, the ductility of AZ31 magnesium alloy will be improved noticeably.

No abstract

No abstract

No abstract

Mg-3Ni-2MnO 2 nanocomposite is fabricated by mechanical-milling under hydrogen atmosphere, and heat transfer and mass transfer of reaction bed is measured through the self-made apparatus. The results shows that: compared to the intrinsic absorption and desorption kinetics of Mg-3Ni-2MnO 2 hydrogen storage material, the accumulated absorption and desorption kinetics of reaction bed behave so different. At the temperature range of 150 -250 during absorption process, the higher the temperature is, the better the intrinsic kinetics behave. But during the same temperature range, the lower the initial temperature of reaction bed is, the better the accumulated absorption kinetics is. During the absorption process, and the temperature of reaction bed wall is lower than center. When the reaction is finished, the reaction bed temperature turn to be homogeneous gradually. The interaction of mass transfer and heat transfer is remarkable during absorption. During desorption, it take so long time for reaction bed to discharge totally. At the initial stage of desorption, the temperature of reaction bed declines, and the center temperature falls lowest and is kept at this temperature for a long time; the higher the reaction bed temperature is, the shorter desorption time is.