Effects of exposure at 700 °C on RT tensile properties in a PM γ-TiAl alloy

Gas atomized powder compacts of a Ti–47Al–2Cr–2Nb alloy have been used to assess their mechanical performance after long-term exposure at potential service temperatures. Unexposed test specimens were prepared with different machining conditions including turning, grinding and electro-polishing and the results revealed that the room-temperature tensile properties were not really affected by the machining conditions. On the other hand, tensile test specimens, when exposed to a temperature of 700 °C up to 400 h, showed a pronounced reduction in tensile elongation irrespective of the machining procedure. A number of techniques including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) experiments and surface roughness measurements, were used to identify the origins of such an embrittlement.