Repeatedly Load-unload-reload Tensile Tests of Fully Lamellar TiAl Alloys

A fully lamellar TiAl alloy was tested using load-controlled tensile unload procedure.The microcracks were measured for each specimen as it was subjected to various repeatedly load-unload-reload processes.The surface density of cracks do not increase with the increasing of unloading stress,indicating that the surface density of cracks is not regarded as damage parameter through statistical analysis.No appreciable effect of the volumetric effects of microcrack damage on the apparent elastic modulus could be found in the repeatedly load-unload-reload processes.Microcrack damage produced at relatively high preloading reduced the fracture stress (σf),fracture strain(εf) and fracture energy per unit (Uf).The facial effect of microcrack damage is appreciable:Microcrack damage produced by high preload on a weakest cross section reduce the fracture stress.