Effect of Cr and Al alloying on the oxidation resistance of a Ti5Si3-incorporated MoSiBTiC alloy

Abstract

The effects of adding Cr and Al on the oxidation behavior of a Ti5Si3-incorporated MoSiBTiC alloy (46Mo-28Ti-14Si-6C-6B, at%) were investigated at 800 and 1,100°C. The addition of Cr and Al largely improved the oxidation resistance of the MoSiBTiC alloy at 800°C due to the formation of Cr2(MoO4)3 and Al2(MoO4)3 in the oxide scales. These protective molybdates mainly formed on the molybdenum solid solution (Moss) and Mo3Si phases that show poor oxidation resistance in the Cr-and Al-free alloy and consequently increased the oxidation resistance of the alloys. However, accelerated oxidation occurred on the 10Al alloy after the long-Term oxidation test, suggesting that the formed oxide scale has limited protection ability. At 1,100°C, the addition of Cr and Al also enhanced the oxidation resistance to some extent by forming Cr2O3 and Al2O3 in the oxide scales.