Effects of heat treatment on the formation of oxygen-rich α layer in TC6 alloy

The oxygen-rich α layer in TC6 alloy at various heat treatment conditions was studied, and the forming thermodynamics and kinetics of the oxygen-rich α layer were discussed. The results show that oxygen-rich α layer forms at the temperature higher than 700°C. Higher the temperature is, thicker the oxygen-rich α layer is. The kinetics curves of the oxygen-rich α layer shows parabolic shape, which can be described as y=at^1/2 and the growth of oxygen-rich α layer is controlled by oxygen diffusion. The forming of oxygen-rich α layer belongs to thermal activation behavior with the thermal activation energy of 140 kJ/mol.