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

摘要

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 ofα2,B2/βand O phases were quantitatively studied.As the heating time increases at 970℃,the mean grain size and content ofα2-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/βphase transition and the globularization of O-phase lamellar grains at 970℃.Calculated by the creep equation and the iso-stress method,the grain size exponent wasμ=1.1 and the relationship between the material constants of B2/βand O phase was KO=1.14KB2/β.