On the Evolution of Banded Microstructures in an Electron Beam Melted Ti 48Al 2Cr 2Nb Alloy

Intermetallic  γ‐TiAl based alloys offer outstanding creep properties, high specific strength and sufficient oxidation resistance at application temperature in the range from 600 to 800 °C. These properties make them prosperous candidatesto substitute heavy Ni‐based alloys offering weightsavings up to 50%. Drawbacksinclude their inherent brittleness as well as reactive melts, which complicate processing and drive costs. In this regard, electron beam melting (EBM), a powder bed additive manufacturing technology, offers low impurity pickup due to the vacuum environment and elevated processing temperature, enabling the manufacturing of TiAl components with increased geometrical complexity. Still, microstructures of electron beam melted titanium aluminides often show a banded character and suffer from Al loss due to process related evaporation decreasing room temperature ductility. As the formation mechanism of banded microstructures in electron beam melted Ti‐48Al‐2Cr‐2Nb (in at. % unless stated otherwise) is not yet fully understood, a scientific explanation is presented in this work.