3D electron backscatter diffraction study of α lath morphology in additively manufactured Ti-6Al-4V

R. DeMott, P. Collins, C. Kong, X.Z. Liao, S.P. Ringer, S. Primig
Ultramicroscopy 218 (2020) 113073.

Although Ti-6Al-4V is a very commonly studied alloy in additive manufacturing, the exact microstructural evolution is still ambiguous due to the extreme conditions and cyclic heating involved in AM. This ambiguity is exacerbated by the presence of multiple solid-solid phase changes, which result in complex microstructures with features at widely varying length scales. One outstanding question is the role that variant selection during the β to α phase transformation plays in determining the final microstructure, especially in electron beam powder-bed fusion. In order to develop a better understanding of the microstructural evolution, thorough characterization of the final microstructure is critical.

In this work we use 3D-EBSD by serial sectioning in a Xe plasma FIB to observe 3-dimesional microstructural features of interest for studying variant selection and microstructural evolution in titanium alloys. All these features are difficult or impossible to characterize fully from 2D data and further analysis of them could reveal important insight into the microstructural evolution during AM. This work highlights the importance of 3D characterization methods for a complete understanding of complex microstructures.

This paper is from our AUSMURI grant on the role of interfaces during additive manufacturing.