Microstructure analysis and mechanical properties of electron beam powder bed fusion (PBF-EB)-manufactured γ-titanium aluminide (TiAl) at elevated temperatures

Abstract

Abstract Additively manufactured γ-titanium aluminide has a high specific strength and temperature resistance. This opens new possibilities for future lightweight constructions for aerospace applications. The objective of this work was to characterize additively manufactured Ti–48Al–2Cr–2Nb alloy specimens, which were successfully manufactured by electron beam powder bed fusion. For microstructural characterization, the as-built state was investigated with light and scanning electron microscopy. In the electron backscatter diffraction analysis, the size and the orientation of the grains were observed. The pore size and distribution were examined in computer tomographic scans, which showed a near fully dense material with a relative density of >99.9%. Furthermore, the hardness curve over the building height was examined in hardness mappings. Thereby, a strong decrease in hardness could be observed with an increase in part height. To evaluate the reliability of the manufactured alloy, quasi-static compression tests were carried out at temperatures up to 650 °C. Within these tests, a high compression strength (σ c,p,0.2,650 °C = 684 MPa) was determined, which implicated a potential substitution of nickel-based superalloy components in aerospace applications under compressive loads.