Fragmentation of α Grains Accelerated by the Growth of β Phase in Ti–5Al–2Sn–2Zr–4Mo–4Cr during Hot Deformation

The fragmentation of elongated α grains accelerated by the growth of β phase in Ti–5Al–2Sn–2Zr–4Mo–4Cr during hot deformation was examined using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). It was determined that boundary splitting resulted in the fragmentation of αE. The kinked sharp α grains, which were formed with help of “civilian” growth of β phase, are necessary structures for the fragmentation of elongated α grains. In addition, the texture results showed an initial deviation from Burgers orientation relationship (OR) in α/β interphase boundaries, indicating that the “civilian” growth of the β phase based on the pre‐existing β grain boundaries implied a constant loss of coherency in α/β interphase boundaries, which also accelerated the fragmentation of elongated α grains. The “civilian” growth of the β phase preferentially occurs in the location surrounded by DT, which promotes the formation of groove that plays an important role in the fragmentation of αE. The “ civilian” growth of the β phase based on the pre‐existing β grain boundaries, suggesting a constant deviation from Burgers OR in α/β interphase boundaries, also accelerates the fragmentation of αE.