The effect of quaternary additions on the microstructures and mechanical properties of orthorhombic Ti2AlNb-based alloys

In an attempt to enhance the mechanical properties of the orthorhombic Ti2AlNb-based (O-based) alloy, six testing alloys were created by adding the quaternary elements to the O-based alloy. The microstructure, creep behavior and tensile properties of these alloys were investigated. The phase constitution was found to be either B2+O, B2+α2+O or B2+α2, depending on the Nb content and aging temperature. The results of the mechanical test showed that V was effective in improving room temperature ductility, while W was effective in enhancing high temperature tensile strength and creep resistance. Among the six alloys, Ti–22Al–20Nb–2W exhibited the best balance with its high-temperature 0.2% proof stress, room temperature ductility, and 1% creep-strain lifetime.