Dependence of flow stress of 8.5Nb-TiAl based alloys on strain rate and temperature

The behavior of high temperature compression deformation for 8.5Nb-TiAl based alloys was studied in this paper. Ti45Al-8.5Nb-0.2W-0.2Mo-0.05Y (TAMWY) and Ti-45Al-8.5Nb-0.2W-0.2Mo-0.3B (TAMWB) exhibit the softening state during the compression tests at 760°C∼1 000°C. The dual logarithm of true stress and true strain for these two alloys is coincided with linear relationship. At above mentioned temperatures, the strain sensitivity m for TAMWY and TAMWB alloy is 0.06∼ 0.09 and 0.06∼0.08 respectively. The activation energy of high temperature deformation is 243kJ/mol, 279kJ/mol and 287kJ/mol for TAMWB alloy; 289kJ/mol, 327kJ/mol and 345kJ/mol for TAMWY alloy. These two alloys are deformed easily at 760°C ∼1 000°C. The deformed constitutive equations for TAMWB and TAMWY alloys are showed as follows: for TAMWB,ε = 6.3 σ^13-7exp(-270 000//RT); for TAMWY, ε̇= 6.6σ^14.1exp(-320 000/RT).