Effect of spark plasma sintering temperature on the multi-scale microstructure evolution and mechanical properties of Ti2AlC/TiAl composites with network architecture

Abstract

In the present work, Ti2AlC/TiAl composites with network architecture were fabricated by the method of spark plasma sintering (SPS) at different temperature using Ti–48Al–2Cr–2Nb pre-alloyed powders and graphene nanosheets (GNSs) as raw materials. The effect of sintering temperature on the multi-scale microstructure evolution and mechanical properties of Ti2AlC/TiAl composites with network architecture was investigated. The results showed that equiaxed γ-TiAl matrix composite reinforced with the continuous network structured micro-Ti2AlC phases could be in-situ fabricated at the sintering temperature of 1200 °C. With the increase of sintering temperature from 1200 °C to 1320 °C, the micro-Ti2AlC continuous network structure gradually transforms into the nearly continuous, quasi-continuous and semi-continuous network. While the equiaxed γ-TiAl matrix gradually transforms into duplex, nearly lamellar, fully lamellar TiAl. Meanwhile, the micro-nano Ti2AlC precipitates would be formed in the TiAl matrix when the sintering temperature exceeds 1200 °C. When the sintering temperature is 1310 °C, the near lamellar TiAl matrix composite reinforced with the quasi-continuous network structured micro-Ti2AlC phases and micro-nano Ti2AlC precipitates is obtained, and the as-prepared composite possesses the best mechanical properties at both room and high temperature due to the synthetic effect of quasi-continuous network structure, intrinsic properties of Ti2AlC and lamellar TiAl.