Investigating the Replacement of Nickel-based Superalloys with Niobium-Based Superalloys in the New Generation of Turbine Blades in the Aero-space Industry

Abstract

To improve the thermal properties of superalloys or replacing them with new materials is necessary to increase engine efficiency. When considerable progress in superalloys is unlikely, researchers started to turn their attention to alternative materials. Metallic silicide alloys are cheaper choices for increasing engine efficiency. The melting point for molybdenum and niobium silicide is much higher than the melting point of the current alloys. This shows these alloys have the potential to increase temperature in gas turbine engines. These alloys have poor oxidation resistance. Improving oxidation resistance of each alloy system is a significant step toward a new material for turbine blades. To improve oxidation resistance in these alloys, many experiments have been done in which alloy elements such as Ti, Cr, Al, Zr, Ta, and Sn have been used. According to these experiments, it can be concluded that Zr is practically ineffective and it cannot improve oxidation resistance in alloys. In some temperatures, Ta is even harmful for oxidation resistance. Sn has the best function to increase oxidation resistance by forming a rich layer of Sn, oxygen penetration into depth is prevented. Despite these alloy elements, they are not enough resistant to oxidation to function in higher temperatures. To be replaced by nickel-based superalloys in gas turbine blades in the aerospace industry they need to have higher oxidation resistance.