Microstructural Refinement of a Ti‐40Al‐8Nb‐0.5B Alloy by Hot Deformation Within (α+β) Phase Field and Subsequent Tempering

In this work, a refined microstructure is obtained in a Ti‐40Al‐8Nb‐0.5B alloy (at%) by hot deformation in the (α + β) phase region and subsequent tempering at 800 °C. The results show that the dynamic recrystallization of α phase occurred during the hot deformation, which resulted in the grain refinement from 56 to 18 µm. Meanwhile, high‐density stacking faults are introduced into the deformed α phase. After tempering at 800 °C for 5 h, ultra‐thin γ lamellar precipitated from the ordered α2 phase by following the Blackburn orientation relationships. The average lamellar spacing is about 10 nm. The refinement of lamellar spacing is mainly attributed to the numerous nucleation sites of γ phase caused by the hot deformation. In addition, fine γ and ω0 particles formed in the retained B2 phase, leading to the formation of a refined near‐lamellar microstructure. A refined microstructure is obtained in a Ti‐40Al‐8Nb‐0.5B alloy by hot deformation in the (α + β) phase region and subsequent tempering. Dynamic recrystallization of α phase results in the refinement of lamellar colonies and the numerous crystal defects result in ultra‐thin lamellar structures.