Microstructural assessment of interaction zone in titanium aluminide/TiC metal matrix composite

Abstract

Abstract Samples of Ti–24Al–11 Nb/TiC composites were heat treated at temperatures between 1000 and 1200°C for several hours and the extent of the reaction zone between the Ti–24Al–11Nb matrix and the TiC particulate was assessed using optical, scanning electron, and analytical transmission electron microscopy. It has been shown that there is an interaction zone surrounding each TiC particle caused by the diffusion of C from the TiC into the matrix and diffusion of Nb into the TiC. The extent of these interactions increases with increase of time and increase of temperature. The phases formed during heat treatment were shown to be Ti3(AlNb)C and (TiNb)C. The significance of these observations is briefly discussed in terms of recent work in which it has been shown that there is no detectable change in the matrix in similarly treated Ti–6AI–4V/TiC composites.MST/946