Hot deformation behavior of in-situ TiBw/Ti6Al4V composite with novel network reinforcement distribution
(National Key Laboratory for Precision Heat Processing of Metals,
Harbin Institute of Technology, Harbin 150001, China)
Harbin Institute of Technology, Harbin 150001, China)
Abstract: TiB whiskers reinforced Ti6Al4V (TC4) alloy matrix composite (TiBw/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.
Key words: titanium matrix composites (TMCs); TiB whiskers; Ti6Al4V alloy; hot deformation; constitutive equation; network microstructure