Fabrication, microstructure and compressive properties of Ti2AlC/TiAl composite with a bioinspired laminated structure

In the present work, Ti2AlC/TiAl composite with a bioinspired laminated structure was fabricated by an in-situ reactive vacuum hot-pressing sintering using flake powder metallurgy (flake PM) with Ti powders, Al powders and graphene nanosheets (GNSs) as raw materials (atomic ratio of Ti–44Al-2.6C). The phases, microstructure and compressive properties of the composite at room temperature were systematically investigated. The results have showed that the composite mainly consist of laminated Ti2AlC, needle-like Ti2AlC and lamellar γ-TiAl/α2-Ti3Al matrix. The laminated Ti2AlC particles are in-situ synthesized during the sintering process, and the Ti2AlC/TiAl interface is mostly an incoherent interphase boundary. The needle-like Ti2AlC particles are formed due to the different solubility of C in γ-TiAl and α2-Ti3Al during the cooling stage, and are preferentially precipitated from TiAl(111) plane and grown along Ti2AlC(0001) plane. Furthermore, the room-temperature compressive strength and strain of the Ti2AlC/TiAl composite in our work could reach 1477.1 MPa and 16.3%, respectively. The comparisons with other TiAl alloys and TiAl matrix composites have indicated that the Ti2AlC/TiAl composites with a bioinspired laminated structure could maintain a better balance of strength and ductility. The characteristic of fracture morphology is mainly crack arresting, pullout and kinking of the laminated Ti2AlC particles.