Effects of Anisotropy in Polycrystalline Ti-7Al Using Far-Field High Energy X-Ray Diffraction Microscopy

On the grain scale, materials are inhomogeneous and anisotropic, and these non-uniformities are often the initiation sites for failure. However, most traditional models assume a homogeneous and isotropic material to predict performance and failure, so focus has begun to turn to micromechanical materials models. These models rely on experiments which supply three-dimensional, in situ, multi-scale data to make accurate predictions. Titanium alloys are commonly used in many biomedical and aerospace applications. However, the alpha-phase in this material is both thermally and mechanically anisotropic due to its

hexagonal closed packed structure. This anisotropy can lead to the development of significant internal stresses in polycrystals. Far-field high energy x-ray diffraction microscopy (ff-HEDM), a synchrotron-based in situ x-ray characterization technique, is employed to study the micromechanical evolution of Ti-7Al under thermal and cyclic loading. In turn, this data will be used for the validation of micromechanical models and eventually the prediction of materials failure.