Microstructure, creep, and tensile behavior of a Ti–21Al–29Nb(at.%) orthorhombic+B2 alloy

The creep and tensile deformation behavior of a Ti–21Al–29Nb (at.%) alloy were studied. Monolithic sheet materials were produced through conventional thermomechanical processing techniques. Heat treatments at all temperatures above 1050 °C, followed by water quenching, resulted in fully-B2 microstructures. Below 1050 °C, either equiaxed or Widmanstätten O-phase precipitated within the B2 grains. RT elongation-to-failure values of less than 2% were recorded for aged microstructures containing 72–78 volume percent O phase. Tensile-creep experiments were conducted in the temperature range 650–710 °C and stress range 48–250 MPa. The measured creep exponents and activation energies suggested that the creep mechanisms were dependent on stress and microstructure. Microstructural effects on the tensile properties and creep behavior are discussed and the data was compared to that for other Ti2AlNb-based alloys.