Advances in Materials Characterization for Ti-based alloys

It has been well established that the composition and microstructure govern the properties of titanium alloys. Traditionally, materials characterization has focused on optical and scanning electron microscopy techniques, which have often provided critical information regarding the size and fraction of key phases and features, such as equiaxed alpha particles, alpha laths, and prior beta grain factors. When necessary, transmission electron microscopy has provided critical information regarding the omega phases and fine scale alpha, and electron backscattered diffraction has given a capability to determine local texture and features such as microtexture. However, key features such as dislocation densities as well as large-scale texture analysis have not been possible. This talk introduces both precession electron diffraction (an transmission electron microscope - orientation microscopy technique with 2 nm resolution) and spatially resolved acoustic spectroscopy (a new method of imaging spatial variations of orientation in specimens over 25 square inches). These techniques have been applied to titanium alloys, and the results related to the mechanical properties.