Deformation mechanisms of the ordered B82-ωo phase

ω structure is commonly observed in Ti and TiAl alloys with a small scale and has a significant impact on their mechanical properties. However, its deformation mechanisms are scarcely investigated due to the small sizes. In this study, a TiAl alloy containing large-scale ordered B8₂-ω_o phase grains was produced through heat treatment, and its room-temperature deformation mechanisms were investigated. Deformation in the ω_o phase primarily occurs through 〈a〉 type and 〈c + a〉 type in prismatic slip, and 〈c + a〉 type in pyramidal slip. Prismatic dislocations can dissociate into partial dislocations accompanied by complex stacking faults (CSF). In contrast, basal slip is more difficult to activate in the applied conditions. The elastic properties of the single ω_o phase were calculated by Density Functional Theory (DFT) method. The results show that the ω_o phase has a strong elastic anisotropy, which fits well with the experimental results.