The lamellar microstructure and fracture behavior of γ-based TiAl alloy produced by centrifugal spray deposition

The lamellar structure and fracture behavior of a γ-based Ti–48A1–2Mn–2Nb (at.%) alloy produced by centrifugal spray deposition (CSD) processing have been systematically investigated. The results show that the formation of the lamellar structure observed with scanning electron microscopy (SEM) results from the dendrite segregation during rapid solidification, and the lath structure revealed by transmission electron microscopy (TEM) stems from phase transformation under α-transus temperature. The CSD processing provides finer lamellar colonies in γ-titanium aluminide, and as a consequense, moderate ductility with appropriate fracture toughness can be achieved. Based on the experimental observations, the toughening mechanisms in the CSD Ti–48Al–2Mn–2Nb alloy are discussed.