Hot deformation behavior of in-situ TiB_w/Ti6Al4V composite with novel network reinforcement distribution

TiB whiskers reinforced Ti6Al4V (TC4) alloy matrix composite (TiB _w/Ti64) was fabricated by in-situ reactive hot pressing. The high temperature deformation behavior of the composite was studied by hot compression tests carried out in the temperature range of 900-1100°C and strain rate range of 0.001-10 s^-1. The results show that the flow stress of the composite decreases with the increase of temperature and the decrease of strain rate. At strain rate of 10 s^-1, discontinuous yielding followed by flow oscillations can be observed, especially in the β phase region. Constitutive equations were constructed based on the peak flow stresses of the stress-strain curves in α+β phase region and β phase region, respectively. Activation energies for the plastic deformation were also calculated in different temperature ranges according to the constitutive equations, namely, 822.3 kJ/mol in α+β phase region and 209.4 kJ/mol in β phase region. The deformed morphologies of the reinforcement network microstructure and the matrix microstructure greatly depend on the deformation regions and parameters.