Microstructure evolution and hot workability of in-situ synthesized Ti2AlC/TiAl composite
(1. Northwest Institute for Non-ferrous Metal Research, Xi’an 710016, China;
2. Key Laboratory of Air-driven Equipment Technology of Zhejiang Province, Quzhou University, Quzhou 324000, China)
2. Key Laboratory of Air-driven Equipment Technology of Zhejiang Province, Quzhou University, Quzhou 324000, China)
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