Tial Alloy Damage And Fracture Process

TiAl-based alloys with high specific strength are the most potential high temperature structural materials for aerospace and auto-engine application. These materials are the high intensity ratio, the low density, the high elevated mechanics performance and resistance high-temperature oxidation performance. However, the application of these materials is hindered by low resistance of damage, and low room temperature ductility and fracture toughness, it is vital to investigate room temperature fracture mechanisms of TiAl-based alloys.This paper sets about studying room-temperature fracture mechanisms of TiAl-based alloys of the fully lamellar microstructure through the measurements of mechanical properties, in-situ observations of fracture surface and FEM calculations on notch specimens, different unload experiment and analyzed SEM and TEM photography. Based on the results of experiments, simulation and FEM calculation, the following are found: The values of mechanical properties measured in tensile are lower than those measured in compression tests. The inferior properties presented in tensile tests are caused by the damages of material, during the deforming there are lots of microcracks initiate in the elasticity stage, which shows the driving force initiating a cleavage crack is the tensile stress rather than the shear strength. Because the is directional solidification materials, as the tensile axis is nearly parallel to the lamellae result to translamellar fracture and a few intergranular fracture. The fracture processing of notch specimens include the initial micro-cracks propagate and finally fracture, no notch specimens propagate many micro-cracks, the remain section reducing result in the strengthen of fracture intensity.Based on the results of the different unload experiment, analyzed SEM and TEM photography, there are the results as follows: Studying the cause of formation of damage, the total of crack act as the parameter of damage of TiAl-based alloys, and studying the parameter of damage effect on the performance of TiAl-based alloys, being damage result in the deteriorating of the materials performance, including reducing elasticity modul, rigidity and fracture energy. During the materials damaged, the dislocations, deformation twins and twin intersections initiate in the materials, but the fracture intensity (b) des not changed with the different damage in the materials.