Microstructural and Phase Analysis of an Additively Manufactured Intermetallic TiAl Alloy using Metallographic Techniques and High-Energy X-Rays

Due to the unique combination of low density and their excellent properties-profile at elevated temperatures, intermetallic γ-titanium aluminide based alloys are a promising structural material for applications in aviation and the automotive industry. Additive manufacturing of a TiAl alloy of nominal composition Ti-48Al-2Cr-2Nb (in at. %), using electron beam melting, resulted in a banded and anisotropic microstructure. In this work, the present microstructure was examined by means of visible light and scanning electron microscopy with regard to morphology and phase distribution. Furthermore, a three-dimensional representation of the microstructure was generated based on differently oriented metallographic specimens. Phase analysis was performed using high-energy X-ray diffraction in order to quantitatively determine present phase fractions and to relate them to findings from microstructural analysis.