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

摘要

The creep and tensile deformation behavior of a Ti-21Al-29Nb (at. percent) alloy were studied. Monolithic sheet materials were produced through conventional thermomechanical processing techniques. Heat treatments at all temperatures above 1050 deg C, followed by water quenching, resulted in fully-B2 microstructures. Below 1050 deg C, either equiaxed or Widmanstatten O-phase precipitated within the B2 grains. RT elongation-to-failure values of less than 2 percent were recorded for aged microstructures containing 72-78 volume percent O-phase. Tensile-creep experiments were conducted in the temperature range 650-710 deg 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 Ti_2AlNb-based alloys.