Fracture Behavior of Directional TiAl Lamellar Structures

In order to assess the influences of macro- and microstructure as well as the cast flaw on the tensile properties, the fracture behavior of a number of ambient tensile TiAl specimens containing directional lamellar microstructure have been analyzed. It is found that all the fractures of tensile specimens are triggered by a critical Griffith crack. According to the desirable ambient tensile properties coincide with the initial cracking facets smaller than 600 mu m, it is proposed that the detrimental effect of the random oriented lamellar colonies on the tensile properties can be eliminated through cast technology improvement.