Abstract:The in-situ micro-nano Ti₂AlC particles reinforced TiAl (Ti₂AlC/TiAl) composite was fabricated using spark plasma sintering. The hot workability of Ti₂AlC/TiAl composite was studied, and the effect of micro-nano particles on flow stress and dynamic recrystallization of composite was discussed. The results showed that the micro-nano Ti₂AlC particles included strengthening and softening effects during hot deformation, resulting in the fact that the Ti₂AlC/TiAl composite exhibited a higher flow stress and more sufficient dynamic recrystallization. The strengthening effect was mainly attributed to the Ti₂AlC particles induced refinement strengthening and hindered dislocation motion at the initial stage. Moreover, the precipitation of nano-TiCr₂ particles induced by stress concentration during hot deformation also contributed to higher flow stress via impeding dislocation motion. Meanwhile, the refined microstructure and dislocation pile-up caused by micro-nano particles during deformation provided more nucleation sites for dynamic recrystallization, which significantly promoted the dynamic recrystallization of the second stage. The present results reveal that the Ti₂AlC/TiAl composite exhibited excellent hot workability, which is important to promote the application of TiAl alloys.

Key words: Ti₂AlC/TiAl composite; spark plasma sintering; hot deformation; microstructure evolution; dynamic recrystallization