Measurement of internal stresses of TiC/titanium based composites after heat-treatment using XRD method

The thermal internal stresses were determined by XRD method in TiC particles reinforced Ti-6Al-4V(T64), Ti-3Al-2.5V(T32) and Ti-6Al-2.5Sn-4Zr-0.5Mo-lNb-0.45Si (T650) based composites. These stresses were generated during the cooling after high temperature processing and heat treatment. In these composites, there is an internal stress character change point, i.e. the metallic matrix phase and TiC particles ceramic phase were found to be under tension and compressive stresses over about 800°C, respectively, and on the contrast under 800°C or so. According to Eshelby Model, this point is corresponding to phase change point of titanium. With the increase of heat treatment temperature, internal stress level increases gradually.