Several core–shell nanosphere chains were observed in the electron beam melted Ti–48Al–2Cr–2Nb samples. The formation mechanism of such core–shell nanospheres, induced by Al vaporization, during the electron beam melting of γ-TiAl was investigated using the HRTEM, FESEM, STEM, and XRD analyses. The solidification of TiAl/Ti3Al lamellae, in the vicinity of the Al-diminished zones, was disclosed by microstructural studies. The core and shell of the nanospheres were characterized as porous Al and α-Al2O3, respectively. Finally, the formation of core–shell nanosphere chains in the additive manufactured γ-TiAl was schematically illustrated. © 2021 Elsevier Ltd