The influence of micro-nano Ti₂AlC on the hot deformation behavior of TiAl alloys

To strengthen TiAl alloys, micro-nano Ti₂AlC precipitates were fabricated in situ by spark plasma sintering using Ti–48Al–2Nb–2Cr pre-alloyed powder and multilayer graphene oxide. The effect of micro-nano Ti₂AlC precipitation on the hot deformation behavior of Ti–48Al–2Nb–2Cr alloy was systematically studied at 1100, 1150, and 1200 °C under strain rates of 0.01, 0.1, and 1 s⁻¹. The fully lamellar structure was transformed to a nearly lamellar structure when the graphene content was increased. In addition, the lamellar colony size significantly decreased and the number of Ti₂AlC particles increased with increasing graphene content. The hot deformation results show that the flow stress of the Ti₂AlC–TiAl composites first increased and then decreased with increasing graphene content, reaching the maximum with the addition of 0.3 wt% graphene. Micro-nano Ti₂AlC particles hindered dislocation slip, leading to a strengthening effect. However, Ti₂AlC particles promoted dynamic recrystallization through grain refinement and dislocation pile-up, resulting in a softening effect. The strengthening and softening effects of the Ti₂AlC–TiAl composites depend on the Ti₂AlC particle content.