Yielding behavior of aluminum-rich single crystalline γ-TiAl

The yielding behavior of Al-rich single crystalline γ-Ti 55.5 at% Al has been measured along near [0 0 1], [0 1 0] and [ 1 ̄ 1 0 ] orientations in both tension and compression and as function of temperature. All three orientations displayed anomalous yielding and a pronounced tension/compression asymmetry. The relative strength of the material, location of the anomalous yielding peak, and tension/compression asymmetry are all orientation dependent. A micromechanical superdislocation model addressing crystal geometry, sense of the applied load, Escaig forces and the Yoo torque is presented to explain the observed experimental results.