Texture Evolution and Mechanical Anisotropy in Dual-Phase Ti₃Al-Based Alloy Loaded at 700 °C to 1000 °C

The super α₂ Ti₃Al-based alloy with a fine grain size of ∼2.2 μm exhibits superplastic elongations over 1000 pct at 920 °C to 1000 °C, 600 pct at 900 °C, 330 pct at 850 °C, and 140 pct at 750 °C. Mechanical anisotropy is observed in this alloy, and relatively lower flow stresses and higher tensile elongations are obtained in the 45 deg specimen loaded at 25 °C to 960 °C. The texture characteristics appear to impose significant influence on the mechanical anisotropy at temperatures below 900 °C (under the dislocation creep condition), and the {111} <2ĪĪ> and {0001} basal textures evolve in the β and α₂ phases after tensile straining. At loading temperatures higher than 900 °C (under the superplastic flow condition), the anisotropy effect is less pronounced and the grain orientation distribution becomes basically random in nature. Rationalizations for the mechanical anisotropy in terms of the Schmid factor calculations for the major and minor texture components in the β and α₂ phases provide consistent explanations for the deformation behavior at lower temperatures as well as the initial straining stage at higher temperatures.