WEI Xiaozhuang, ZHANG Youfeng, GAO Yifei, YING Jie
(College of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620, China)

Abstract: TiB-TiB₂ composite ceramics were fabricated by in-situ reaction synthesis and pressureless sintering in vacuum atmosphere the mixture of Ti and B powders. The microstructure and phase types of the samples were observed by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Results showed that there are pores and defects in the composite ceramics, and the samples exhibit four phases:TiB, TiB₂, TiO and Ti6O. The grain sizes are uniformly distributed in composite ceramics with B content of 5vol.%, 10vol.% and 25vol.%.A small amount of needle-like TiB and TiB₂ grains is shown in the fractographs of TiB-TiB₂ composite ceramics with B content of 5vol.% and 10vol.%, and with the increase of B, more needle-like and sheet TiB and TiB₂ phases appear in the froctographs of TiB-TiB2 composite ceramics, mixed in large grains.

Key words: in situ reaction; composite ceramics; microstructure; TiB-TiB₂