Near-surface residual stress in TiAl after high temperatureWednesday (28.09.2016) 15:45 - 16:00 Part of:
It is well known that the room temperature ductility of gamma-based titanium aluminide alloys is significantly reduced by exposure to elevated temperatures. In some cases exposure can even lead to brittle fracture on the reloading of an initially ductile alloy. As the reason behind the loss of ductility is unknown, development of mitigating strategies remains difficult. In the past it has been reported that a tensile surface stress develops after exposure. This paper is concerned with re-confirming this finding and determining the state of stress within the near surface region, as a function of depth, both before and after exposure in air at 700°C for 1 hour. It has been found that the significant near surface compressive stress is reduced after exposure and that a significant tensile stress develops within the first micron of material below the surface.