Polycrystals of the γ-phase alone (54.1at%Al) were prepared by extrusion. The specimens contained interstitials which were typical of technical-purity material. Due to dislocation pinning by these impurities and precipitates, internal friction measurements indicated no relaxation between room temperature and 950K. At 1100K, a relaxation maximum was observed; with an activation enthalpy of 2.97eV and a pre-exponential of 2.5 x 10-16s. This was attributed to the reorientation of structural defects. At temperatures above 1200K, the damping exhibited a marked frequency-dependent increase with temperature. This was characteristic of diffusion-controlled dislocation climb.

Internal Friction Measurements of γ-TiAl. M.Hirscher, D.Schaible, H.Kronmuller: Intermetallics, 1999, 7[3-4], 347-50