An atomic study of the transitional region between γ/γ laths in γ-TiAl

• Orientation of the γ lath is found to be highly dependent on its Ti/Al ratio.
• IFFT is applied to characterize γ/γ lath interface.
• The special APB twin interface is observed.

In the present study, a transitional region between two thick γ laths is investigated with TEM, HAADF-STEM, EDX and HRTEM. The results show that the transitional region consists of three thinner γ laths, and all the thick and thin laths have a true twin relationship. The interface between γ/γ laths is basically a twin-related interface but involving a rigid body translation of the adjacent lamellae, and misfit compensating has been observed along the interface. Ti segregates into the transitional region, which is essential to formation of the three thin γ laths. Based on the characterization of the transitional region, the formation mechanism of the transitional region is revealed.