In-situ synthesized a dual-scale Ti2AlC reinforced TiAl composites with superior mechanical properties

Abstract

To enhance the mechanical properties and service temperature of TiAl alloy, the dual-scale Ti2AlC particles reinforced TiAl composites were successfully designed and fabricated by spark plasma sintering (SPS), utilizing pre-alloyed Ti–48Al–2Nb–2Cr powder and multi-walled carbon nanotubes. The TiAl composites exhibited a fully lamellar structure, with micro-laminated Ti2AlC particles formed at grain boundaries and nano-laminated Ti2AlC particles precipitated at the interfaces of α2 and γ lamellae by adding 0.5 wt% multi-walled carbon nanotubes. The TiAl composites exhibited excellent mechanical properties at room temperature and elevated temperatures. The ultrahigh tensile strength of TiAl composite was 599.6 MPa at 800 °C which was improved by 28.3 % compared with TiAl matrix, while the fracture strain remained 4.2 % without sacrifice. These superior mechanical properties were mainly attributed to the refinement strengthening, solid solution strengthening, and the formation of dual-scale Ti2AlC particles. Moreover, the dual-scale Ti2AlC particles reinforced α2 and γ lamellar interfaces and lamellar colony boundaries resulting in improvement of strength and toughness simultaneously. The TiAl composite was reinforced by dual-scale Ti2AlC particles, which expected to further break the property limitation of TiAl alloy and expanded its application at high temperature.