Microstructural heterogeneity in hexagonal close-packed pure Ti processed by high-pressure torsion

Microstructural evolution was studied quantitatively by electron backscattering diffraction in commercial purity Ti processed by high-pressure torsion (HPT) at room temperature. The results show that a heterogeneous microstructure develops during HPT processing with regions of both nanocrystalline grains (1 mm. The mechanism of grain refinement is characterized by dynamic recrystallization and the continuous formation of a necklace-like array of fine grains gradually consumes the larger grains in subsequent passes