Effects of microcrack-damage on fracture behavior of TiAl alloy part I displacement-controlled tensile test

Specimens of a directionally solidified cast of a fully lamellar TiAl alloy were tensile tested using displacement-controlled procedure. Numbers of microcracks were measured for specimens after they were subjected to various preload–unload processes. Combined with detailed fracture surface observations, the following effects of microcrack-damage on fracture behavior of TiAl alloy are proposed—(1) Volumetric effect: the apparent plastic elongation incorporates both plastic strain and the elongation caused by microcracks. (2) Volumetric effect: microcracks produced in entire specimen volume decrease the apparent elastic modulus and produce a stress-softening sector of the load–displacement curve just before final fracture. (3) Facial effect: microcracks extended on a weakest cross-section decrease and determine the fracture load.