Tensile creep deformation and fracture behaviors of the lamellar TiAl alloy of elemental powder metallurgy

Under the basis of the measured apparent activation energy and TEM observation for the dislocation structure, the creep deformation of the EPM alloy under the conditions of 150-250 MPa/775-900 deg C is assumed to be progressed by the dislocation glide in the gamma lath but is considered to be controlled by the dislocation climb. However, in condition of 100-150b MPa/800 deg C, it is suggested that the diffusional creep dominates the creep deformation rather than dislocation motion. Pore formation and coalescence at the lamellar grain boundaries having the normal direction to the tensile stress axis are observed to be the cause of the creep fracture.