Equiaxed α microstructure evolution in wrought Ti-10Al-1Zr-1Mo-1Nb alloy during annealing

Abstract Evolution of α microstructure on the thermomechanical treated Ti-10Al-1Zr-1Mo-1Nb alloy during annealing was studied. The solution-treated materials were groove-rolled or uniaxially compressed in the α+β region and annealed at 1173 K. The flow softening behavior and crystal rotation in α platelets revealed an evolution of deformation texture. The volume fraction of equiaxed α grains was increased during annealing. Especially in the material compressed at a strain rate of 1 s−1, the equiaxed α grains developed within a shorter annealing duration than 1.8 ks. The deformation with higher strain rates promoted the division and fragmentation of α platelets during annealing. Transmission electron microscopy and X-ray diffraction analyses were employed to characterize dislocation components and structure, where the installed screw dislocations provided a fine substructure and high energy α/α boundaries in α platelets. The triple junction consisting of α/β boundaries and α/α boundaries may provide a site for thermal grooving, which induces the division and fragmentation of α platelets. Therefore, deformation at a higher strain rate is necessary in α+β processing to develop a fine equiaxed α microstructure for the Ti-10Al-1Zr-1Mo-1Nb alloy during annealing.