Characterization on Solid Phase Diffusion Reaction Behavior and Diffusion Reaction Kinetic of Ti/Al

The solid phase diffusion reaction behavior between Ti and Al was characterized from 520℃ to 630℃ for different annealing time with titanium and aluminum being superfluous. When the samples are annealed up to 46 h, only intermetallic TiAl₃ phase forms and grows at the Ti/Al interface. It can be found that the growth rate of TiAl₃ towards TiAl₃/Al interface is more rapid than that towards Ti/TiAl₃ interface. Additionally, the solid-state diffusion reaction kinetic equation of TiAl₃ was successfully established in the present work. The reaction activation energy of Ti/Al is calculated to be 170.1 kJ·mol^-1 and dynamic index n is 0.5. Hence, the growth of TiAl₃ is controlled by normal parabolic law with annealing time. Ti/Al powder compact was employed as experiment material to identify the proposed reaction kinetic equation for the growth of TiAl₃. It is suggested that no extra aluminum is found in the specimen annealed at 590℃/4.5 h, while the aluminum is still found at 590℃/3.5 h, indicating that it is in a good agreement with the developed solid-phase diffusion reaction equation.