Enhancing the mechanical and tribological properties of TiAl alloy by network structured Ti2AlC

Network-structured Ti2AlC/TiAl composites were successfully designed by spark plasma sintering utilizing Ti-45Al-8Nb powder with different carbon nanotubes (CNTs) contents. The microstructural evolution, compression property and wear resistance of network-structured Ti2AlC/TiAl composites were investigated. The results showed that the microstructure was significantly refined, which was attributable to the network-like Ti2AlC phase that precipitated at the lamellar colony boundaries by in situ reacting between the CNTs and TiAl powders. As the CNTs contents increased from 0 to 1.0 wt.%, the compressive strength of the composites first increased and then decreased, while the friction coefficients and wear rate were reversed. Typically, the TiAl composites exhibited the best mechanical and tribological properties synchronously by adding 0.6 wt.% CNTs, which increased the ultimate compressive strength (1921.9 MPa) by 25.6% and decreased the wear rate (1.45x10(-4) mm(3) N-1 center dot m(-1)) by 38.8% compared to pure TiAl alloy. The improvement in the mechanical properties of the Ti2AlC/TiAl composites was primarily caused by pull out, debonding, and delamination effecting of Ti2AlC particles. In addition, the Ti2AlC/TiAl composites exhibited low friction coefficients and wear rates, attributable to the load-carrying effect induced by network-like Ti2AlC particles during friction.