|About this Abstract
||2022 TMS Annual Meeting & Exhibition
||Phase Transformations and Microstructural Evolution
||Understanding Microstructural Evolution in Powder Bed Fusion Additive Manufacturing: Observations of Phase Transformation in Ti-6Al-4V Using In Situ TEM Heating Experiments
||Sriram Vijayan, Carolin Fink, Joerg Jinschek
|On-Site Speaker (Planned)
Powder bed fusion (PBF) additive manufacturing results in steep thermal gradients (~10^6 K/m) and rapid thermal cycles (~ 10^3 K/s), which significantly affects the microstructural evolution within the build. The non-equilibrium process conditions result in metastable microstructures and columnar grain morphologies, which deviate significantly from conventionally processed alloy microstructures. New in situ tools can observe thermally activated phase transformations (PT) under AM process conditions. Here, we use a modified MEMS-based heating stage to simulate ‘AM like’ processes inside a transmission electron microscope (TEM). This modified device enables us to study the microstructural response of a material under the combined influence of large thermal gradients (10^6 K/m) and rapid thermal cycling. The approach is used to observe the sequence of PT in Ti-6Al-4V to further our understanding on microstructural evolution under super-transus thermal cycling and sub-transus thermal cycling conditions as experienced during electron beam melting PBF processing.
||Additive Manufacturing, Phase Transformations, Characterization