Three-dimensional alpha colony characterization and prior-beta grain reconstruction of a lamellar Ti-6Al-4V specimen using near-field high-energy X-ray diffraction microscopy

摘要

Near-field high-energy X-ray diffraction microscopy has been used to characterize the three-dimensional (3-D) crystallographic orientation field of the hexagonal close-packed alpha phase in a bulk Ti-6Al-4V specimen with a lamellar (beta-annealed) microstructure. These data have been segmented using a 3-D misorientation-based grain finding algorithm, providing unprecedented information about the complex 3-D morphologies and spatial misorientation distributions of the transformed alpha lamella colonies. A 3-D Burgers orientation relationship-based flood-fill algorithm has been implemented to reconstruct the morphologies and crystallographic orientations of the high-temperature body-centered cubic prior-beta grains. The combination of these data has been used to gain an understanding of the role of the prior-beta grain structure in the formation of specific morphologies and spatial misorientation distributions observed in the transformed alpha colony structures. It is hoped that this understanding can be used to develop transformation structures optimized for specific applications and to produce more physically realistic synthetic microstructures for use in simulations.