Effect of Cr and Al alloying on the oxidation resistance of a Ti 5 Si 3 -incorporated MoSiBTiC alloy

The effects of adding Cr and Al on the oxidation behavior of a Ti 5 Si 3 -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 Cr 2 (MoO 4 ) 3 and Al 2 (MoO 4 ) 3 in the oxide scales. These protective molybdates mainly formed on the molybdenum solid solution (Mo ss ) and Mo 3 Si 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 Cr 2 O 3 and Al 2 O 3 in the oxide scales.