In-situ synthesized a dual-scale Ti2AlC reinforced TiAl composites with superior mechanical properties
Yupeng Wang, Guangfei Rong, Tengfei Ma, Zhanxing Chen, Xinfang Zhang, Dongdong Zhu, Hongze Fang, Ruirun Chen
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.