Effect of composition on the mechanical properties of newly developed Ti2AlNb-based titanium aluminide

Among titanium aluminides Ti2AlNb-based alloys have received considerable attention in recent years, as potential materials for high-temperature applications in jet engines. Several compositions based on Ti-22Al-25Nb with molybdenum, silicon, zirconium additions were developed. The investigated microstructures consist of bi-lamellar O-Ti2AlNb structure with alpha(2)-Ti3Al nodules, surrounded by a B2 matrix. Effects of Aluminium and Niobium contents are, especially, examined on tensile properties, on creep strength and on oxidation resistance. It is shown that a high Al/Nb ratio is required for a good oxidation resistance, but is associated with a loss of ductility. Reducing Nb results in a decrease of creep strength that can be compensated by zirconium and/or molybdenum additions which improve the creep resistance significantly without impairing ductility or yield stress. (c) 2004 Elsevier Ltd. All rights reserved.