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 °C to 630 °C 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 °C/4.5 h, while the aluminum is still found at 590 °C/3.5 h, indicating that it is in a good agreement with the developed solid-phase diffusion reaction equation.