Fracture Behavior of the New beta Ta-TiAl Alloy During the Hot Deformation

As-cast TiAl-3Ta-x(Cr, W)(at%) alloys were hot compressed by Gleeble-3800 thermal simulation tester in the temperature range from 1150 to 1300 degrees C and strain rate range from 0.1 to 1 s(-1) for high temperature fracture behavior and microstructure evolution study. The results show that the main fracture modes consist of 45 degrees shear fracture and longitudinal fracture on free-surface, but the crack location is different. Moreover, the cracking degree increases with the decreasing of deformation temperature, or the increasing of strain rate and height reduction. In the high strain rate range, deformation twinning dominates the entire deformation process. Moreover, the cracks nucleation sites are observed at grain boundary of the colonies and/or interfaces between lamellae of the specimens, and cracks initiate and propagate perpendicular to the compression axis.