Papers by Author: Wen Xia

Abstract: In this paper, a new method mesoscopic been studied for metal material deformation to fracture process. In the polycrystalline material plastic flow process, mesoscopic structural features was obtained for translation - vortex by digital image correlation principle. A preliminary analytical method of material deformation is established. The behavior of plastic deformation of 7B04 high strength aluminum alloy was analyzed. Grain groups deformation, amount of rotation and the energy dissipation distribution were analyzed. An important deformation features is that micro cracks were bred in severe plastic strain region on mesoscopic scale. Based on the stress concentration, the formation of rotational deformation can be regarded as the beginning of an irreversible damage criterion. The Rotation of grain groups is the reason of the formation of microcracks.

Abstract: Without addition of any thermodynamically stable perovskite compound such as PbTiO3, Pb(Mg1/3Nb2/3)O3 was fabricated by a new sol-gel route, and the processing parameter was studied. The result showed that the chelating effect of ammonium citrate was relatively better than that of citric acid in this system. When the ratio of ammonium citrate to Nb2O5 was 8.33, the colloid of Nb2O5·nH2O was in state of transparency. The effects of heat treatment on the formation of perovskite phase of Pb(Mg1/3Nb2/3)O3 powders were characterized by X-Ray Diffraction (XRD) method. With increasing heat treatment temperature or holding time, pyrochlore phase turned into perovskite phase gradually, and after second calcination, the content of perovskite phase increased significantly from 54% to 72%.