Microstructure refinement assisted by α-recrystallization in a peritectic TiAl alloy

Abstract

Fine-grained nearly-lamellar (FGNL) microstructures and ultrafine α2/γ lamellar microstructure were successfully obtained by means of α-recrystallization in a Ti–48Al–2Nb–2Cr alloy. The dynamic recrystallization of α phases and subsequent cooling control contributed to microstructure refinements, which were governed by small-strain α-deformation. Lamellar grain refinement is due to dominating continuous dynamic recrystallization (CDRX). Lamellar structure refinement is mainly achieved by the increase in γ lamellae precipitation sites by α-deformation and fast cooling. Finally, the microstructure evolution and control mechanisms were illustrated, suggesting a promising method for improving the mechanical properties of TiAl alloy.

Keywords

• Titanium aluminides
• α-Processing
• Microstructure refinement
• Continuous dynamic recrystallization
• Phase transformation