Collaborative behavior in α lamellae and β phase evolution and its effect on the globularization of TC17 alloy

The globularization behavior of the basketweave microstructure in TC17 alloy is quantitatively analyzed during deformation and subsequent heat treatment. Collaborative behavior in the α lamellae and β phase evolution are proposed to affect globularization based on the transmission electron microscopy (TEM) and high-resolution electron backscatter diffraction (EBSD) observations as follows: (i) the interleaved α lamellae restrain the rotation of neighboring α lamellae and promote the formation of low-angle boundaries (LABs) and grooves, and then (ii) the β phase has a positive effect on facilitating the complete separation of α lamellae during deformation. During heat treatment, (iii) the formation of the LABs in the β grain interiors accelerates the appearance of necklace-like α grains, and (iv) the α lamellae promotes the break-up of β phase while the β phase has a positive effect on facilitating the complete separation of α lamellae. In other words, Collaborative behavior in α lamellae and β phase evolution promotes the globularization of TC17 alloy containing a basketweave microstructure. Except for the boundary splitting and termination migration, the mechanism of substructure rotation also participates in the globularization of TC17 alloy containing a basketweave microstructure, which is different to that of the alloys containing a colony microstructure.