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17 results on '"Liu, Wenxi"'

11. Transformation-induced plasticity of expandable tubulars materials

Author

Liu Jie, Guo Rui-song, Xu Ruiping, Liu Wenxi, and Zhang Yu-xin

Subjects
Materials science, Mechanics of Materials, Mechanical Engineering, Martensite, Diffusionless transformation, Metallurgy, Hardening (metallurgy), General Materials Science, Plasticity, Condensed Matter Physics
Abstract

A new concept on strengthening-plasticity is presented in this paper, along with the design rules of the alloys with high expandable performance. The plasticity of expandable alloys induced by the γ→ɛ martensitic transformation, can be obviously improved. In order to enhance transformation-induced plasticity, alloys with low stacking-fault energy and high starting temperature of ɛ martensite M s(ɛ) should be looked for. Therefore, a formula for the calculation of M s(ɛ) of Fe-based alloys is also given in this paper in order to facilitate the design of expandable tubular materials.

Published
2006

12. The role of Y2O3 in fine-grained (Y,Mg)-PSZ/MgAl2O4 during long term heat treatment

Author

Chen Yu-ru, Liu Wenxi, Zhang Qi, Yuan Qiming, and Wu Houzheng

Subjects
Toughness, Materials science, Process Chemistry and Technology, Thermal decomposition, Mineralogy, Microstructure, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Chemical engineering, Phase (matter), visual_art, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Thermal stability, Ceramic, Chemical decomposition, Eutectic system
Abstract

Fine-grained (Y, Mg)-PSZ/MgAl 2 O 4 ceramics are prepared by coating-coprecipitation technology. This kind of material exhibits very good thermal stability at 1100°C for it possesses strength values over 900 MPa and toughness over 15 MPam 1/2 even as the ageing time reaches 800h. The microstructures and phase compositions are examined with XRD, SEM and TEM. The results show that the material derives from a new sub-eutectoid decomposition reaction: c-ZrO 2 →c′-ZrO 2 +t-ZrO 2 +MgO, which is different from the thermal decomposition of conventional Mg-PSZ without Y 2 O 3 addition. Furthermore, two kinds of precipitations can be detected according to their stabilizer. It is found that the tweed-like and colony-like t-ZrO 2 phases in the ceramics, which are stabilized by Y 2 O 3 , can grow up and lead to an increase in volume of the transformable t-ZrO 2 with heat treatment. Only the transformable t-ZrO 2 , originating from the eutectoid decomposition of Css, plays an important role in toughening the matrix. 1998 Elsevier Science Limited and Techna S.r.l.

Published
1998

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