High temperature deformation behavior of powder metallurgy TiAl based alloys

The high temperature mechanical properties and deformation behavior of powder metallurgy Ti-47.5Al-2.5V-1.0Cr alloy were investigated in a temperature range of 600 to 1 050 ℃ and a strain rate range of 0.002 to 0.2 s^-1.The results show that during the hot deformation the yield strength of the TiAl based alloy decreases,whereas the ductility tends to rise with increasing deformation temperature and decreasing strain rate.The interrelations of peak flow stress,strain rate and deformation temperature can be described by Arrhenius' equation modified by a hyperbolic sine function,which indicates that the hot compression deformation is controlled by thermal activation.Under the deformation condition of 800 to 1 050 ℃/0.002 to 0.2 s^-1,the strain sensitivity of the alloy is 0.152,whereas the deformation activation energy of high temperature deformation is 376 kJ·mol^-1.