An in-situ transmission electron microscopy study on room temperature ductility of TiAl alloys with fully lamellar microstructure

Abstract

An in-situ transmission electron microscopy study was conducted at room temperature in order to understand an underlying mechanism on room temperature ductility of TiAl alloys. From in-situ straining transmission electron microscopy experiments, it was revealed that the crack path is different between the TiAl alloys with/without room temperature ductility. The crack in TiAl alloys having room temperature ductility interacted with lamellae by forming bridging ligaments between the two α2 lamellae and the γ lamellae. In contrast, the cracks in TiAl alloys without room temperature ductility propagated along grain (colony) boundaries showing brittle intergranular fracture. Finally, we proposed the important microstructural factors to have room temperature ductility of TiAl alloys.