Microstructure and hot flow stress at 970 °C of various heat-treated Ti2AlNb sheets

Abstract

The microstructure and hot tensile behaviors of the different heat-treated Ti2AlNb sheets were investigated by backscattered electron image (BSE), electron backscattering diffraction (EBSD), transmission electron microscope (TEM) and tensile tests. The grain sizes and contents of α2, B2/β and O phases were quantitatively studied. As the heating time increases at 970 °C, the mean grain size and content of α2-phase increased. The grain shapes and distributions of the O-phase lamellar grains were affected by the heat treatments. The plastic deformation promoted the O → B2/β phase transition and the globularization of O-phase lamellar grains at 970 °C. Calculated by the creep equation and the iso-stress method, the grain size exponent was $$\mu = 1.1$$ and the relationship between the material constants of B2/β and O phase was $$K_{{\text{O}}} = 1.14K_{{{\text{B}}2/\upbeta }}$$ .