Atomic-scale understanding of the γ/α2 interface in a TiAl alloy

Abstract

The eutectoid reaction often produces lamellar structure of two alternating phases, which exhibits promising mechanical properties because of high density interfaces. However, the atomic-level understanding of these interfacial structures remains controversial. Here we report the atomic structure of γ/α2 interface in a fully lamellar TiAl alloy investigated by the aberration corrected transmission electron microscopy and density functional theory (DFT) simulations. The results reveal that the orientation relationship between α2/γ interface in TiAl alloy always follows (0001)α2||{111}γ and ⟨11–20⟩α2||⟨1–10⟩γ with a semi-coherent lattice match due to the ultralow interfacial energy predicated by DFT calculation.