Interfacial characteristics and thermal stability of polymer-derived SiCf/Ti composite fabricated by powder hot isostatic pressing

Abstract

The novel SiCf/Ti composite is prepared by hot isostatic pressing (HIP) with polymer-derived (PD) SiC fiber and powder titanium alloy as raw materials in this work. The interfacial characteristics and thermal stability of the PD SiCf/Ti composite have been systematically investigated. The interfacial properties of the PD SiCf/Ti composites are quantified to discuss the interfacial reaction mechanisms and kinetics. The results show that with the proposed HIP process, the powder matrix can be near-fully dense, and the matrix and SiC fiber are well bonded with a uniform interfacial layer. The major interfacial products are C-Ti compounds and Si-Ti compounds, which are formed by atomic diffusion reaction. During subsequent thermal exposure conditions, the interfacial layer growth is temperature-dependent and diffusion-controlled, following the parabolic relation and Arrhenius law. The frequency factor k0 is 102–103 times lower than that in the chemical vapor deposition (CVD) SiCf/Ti composites, showing better interfacial thermal stability. After thermal exposure, the element diffusion becomes significant, and the microhardness of the near-interface zone is noticeably greater than the matrix microhardness because of the atomic diffusion of C. The microhardness of both the matrix and near-interface zone reaches the highest value after 900 °C/9 h thermal exposure. It is concluded that the PD SiCf/Ti composites with good thermal stability can be successfully fabricated by powder HIP.