Hideyuki Murakami

This study investigated the effect of Re addition on the microstructural evolution and oxidation resistance of Co-Cr-Ta-Ti-C alloys. The alloys tested in this study consisted of a Co-rich matrix with mixed HCP and FCC phases, together with TaTiC2- and Ti-based carbides. The addition of Re promotes the precipitation and growth of a CoCr-rich σ-phase. Differential thermal analysis (DTA) showed that the melting temperatures did not drastically change up to 10 at% Re addition, whereas 15 at% Re addition significantly increased the melting temperature of the alloys. Oxidation tests in air at 1200 °C showed that an excessive Re content could lead to a deterioration in oxidation resistance, mainly due to the accelerated formation of volatile Re oxides.