A SIMPLE-MODEL OF DEFORMATION OF TI48AL-2CR-2NB AT HIGH-TEMPERATURES

The point of maximum deformation resistance (minimum creep rate) and the subsequent softening (tertiary creep) can be modelled on the basis of the tranformation of the fully lamellar structure into the globular structure by dynamic recrystallization. The globular material contains a steady-state dislocation structure with subgrains of size w = 8bG/σ in fine grains of size d ≈ 2 w. As the volume fraction with globular structure increases with strain at the expense of the lamellar structure, the deformation resistance approaches the steady state resistance of the globular structure which is of the order of magnitude predicted by the natural creep law for a solid solution. © 1994.