Textures of rectangular extrusions and their effects on the mechanical properties of thermo-mechanically treated, lamellar microstructure, Ti-47Al-2Cr-2Nb-0.15B

Textures of alpha(2) and 7 phases in Ti-47Al-2Cr-2Nb-0.15B (at.%) rectangular billet, extruded below its a transus temperature, were evaluated and their relation to the mechanical properties of TMTL microstructure was investigated. Strong alpha(2) phase texture {11 (2) over bar}<10<(1)over bar>0> was found after extrusion and it evolved into {11 (2) over bar}<10<(1)over bar>0> recrystallization texture via oriented growth during a solution treatment. The alpha/alpha(2) phase texture changes alpha grain growth behavior at T-alpha, such that it is slow at first but becomes rapid when the solution time exceeds a critical value, creating a new method of obtaining fine-grained TMTL microstructure. Mechanical properties of the TMTL microstructure were shown to be closely related to the Kearns texture factor of the alpha(2) phase along the loading direction. The center and edge of as-extruded billet have distinct gamma phase textures, dominated by beta fiber (center) and featuring multiple texture components (edge), respectively. In the highly strained edge region, the presence of C-twin, Y, and Z texture components suggests the occurrence of mechanical twinning and shear band deformation, while BIG auxiliary component was found to act as a transition band from deformation to cubic recrystallization texture, in support of the oriented nucleation hypothesis for the formation of cubic texture. (C) 2014 Elsevier Ltd. All rights reserved.