Growth Behaviors of Alpha Cases in Ti-6Al-4V and Ti-10V-2Fe-3Al Alloys during High Temperature Heat Treatment in Air

摘要

It is known that titanium alloys have a high affinity for oxygen during exposure at high temperatures. Therefore oxidized layers, which are called alpha cases, are formed on the surface of titanium alloys during high temperature exposure. For the practical application of titanium alloys, it is very important to clarify the behavior of alpha case growth. Then the results will be reflected in the processes for manufacturing aircraft components. For this study, two titanium alloys, Ti-6Al-4V and Ti-10V-2Fe-3Al, as common aircraft structural titanium alloys, were selected. The alpha cases of both alloys were investigated with heating in air. It was revealed that the alpha cases of both alloys were formed in accordance with the parabolic law. However, the growth rates of the alpha cases on the two alloys differed: the growth rate of Ti-10V-2Fe-3Al was faster than that of Ti-6Al-4V. The reason for the faster growth rate of Ti-10V-2Fe-3Al is considered by the lower activation energy of self-diffusion in beta titanium.