On Interfacial Microstructure Evolution in an Isothermally Exposed SiC Fiber-Reinforced Ti-17 Matrix Composite

Abstract

The kinetics and mechanisms of interface reactions in a unidirectional continuous SiC fiber-reinforced Ti-17 matrix composite were investigated using transmission electron microscopy and scanning electron microscopy. It was found that a reaction zone (RZ) consisting of two-layered TiC-type carbide forms at the fiber/matrix interface during fabrication of the composite. After isothermal exposure at elevated temperatures, the two-layered TiC-type carbide is inherited, and a new TiC-type carbide layer forms within the RZ after exposure at temperatures lower than 900°C, while a new Ti3C2-type carbide layer forms after exposure at 900°C. It was also observed that the growth of RZ is a diffusion-controlled and temperature-dependent process, obeying the Fick's law-based parabolic relationship and the Arrhenius equation. Two material constants, the temperature-independent rate constant k0 and activation energy Q, are determined as 31.5 × 10−4µm/s1/2 and 49.9 kJ/mol, respectively.

Investigation of interface debonding behaviour in a unidirectional SiC fibre reinforced Ti-17 composite by a single fibre push-out technique

“…On the other hand, the development of the interfacial reactions is much more limited than that in other composite systems due to the difference of fibre/matrix chemical reactivity. 54 As a result, the reaction zone (RZ) in other composite systems, as listed in Table 1, is normally a few microns in thickness while it has a thickness of 0.4 mm in this study. It is believed that relatively strong interface bond can be promoted at the interface where stable chemical reactions are fully developed.…”