SEMINAR
The State Key Lab of
High Performance Ceramics and Superfine Microstructure
Shanghai Institute of Ceramics, Chinese Academy of Sciences

　　中 国 科 学 院 上 海 硅 酸 盐 研 究 所 高 性 能 陶 瓷 和 超 微 结 构 国 家 重 点 实 验 室

　　Normal and abnormal grain growths in BaTiO3 fibers

　　Speaker

　　彭 飞 教授

　　Department Materials Science and Engineering

　　Clemson University，South Carolina

　　时间：2014年12月24日（星期三）下午 2:00

　　地点： 2号楼607会议室 （国家重点实验室）

　　欢迎广大科研人员和研究生参与讨论！

　　Abstract

　　The grain growth mechanisms along the BaTiO3 fibers were studied between 1150°C and 1250°C. The normal grain growth always reached a stagnant stage after certain heat-treatment duration caused by the surface pinning effect. However, the abnormal grain growth (AGG) was not pinned by such surface effect, and can grow continuously. The confined normal grain (or matrix grain) size provides the driving force for AGG. The fiber diameter has an important influence on the grain growth behaviors. Submicrometer fibers have relative small stagnant grain sizes, resulting in large driving force for AGG. Abnormal grain growth occurred below 1200°C in the submicrometer diameter fibers, but was not observed at the same temperature in the fibers with diameter of above 1 μm. Due to the large AGG driving force, large number densities of abnormal grains were observed in submicrometer fibers, resulting in “bamboo-like” microstructure. Fibers with diameters of 1–2 μm were able to be converted into single crystal fibers up to several tens of micrometers due to the relative small AGG driving forces.

　　Biography

　　Fei Peng is currently assistant professor of Materials Science and Engineering Department at Clemson University. He obtained his Ph.D. degree in 2009 at Georgia Institute of Technology. His research has been focused on kinetics of materials, such as grain growth kinetics and diffusional phase transformations. He has made original contributions to the understanding of grain growth in one-dimensional fibers and of corrosion and oxidation protection of ultra-high temperature ceramics under extreme environments. He has extensive ceramic materials’ processing and characterization experience, especially in ceramic fibers and coatings. He has published 24 peer-reviewed journal papers.