Formation of Diffusion Layer on Ti-6Al-4V Alloy during Longtime Friction with Al

Elements’ diffusion between Ti-6Al-4V alloy and Al in the process of sliding was investigated from 400 °C to 600 °C. The results showed that the atoms were diffused at the Ti-6Al-4V/Al interface. When sliding at 400 °C and 500 °C, no intermetallic compound was detected on the surface of Ti-6Al-4V alloy. When sliding at 600 °C, intermetallic TiAl3 was formed and grew on the surface of Ti-6Al-4V alloy. The diffusion thickness of Al atoms on the surface of Ti-6Al-4V alloy increased with increasing time and temperature. The diffusion kinetic equation of Al atoms on the surface of Ti-6Al-4V alloy was successfully established. The diffusion activation energy of Al atoms in the sliding process was calculated to be 28.22 kJ·mol−1 and the dynamic index n was 0.5. The diffusion growth of Al atoms was controlled by normal parabolic law with time.