Investigations on the mechanics and tribology of multilayer graphene nanosheet in TiAl aviation composites

Requirements of low energy consumption and material-volume reduction in the aerospace industry have spurred improvements of mechanical and tribological behaviors of TiAl (TA) alloys. TA-graphene (TAG) has poorer mechanical properties (6.02 ± 0.42 GPa nano-hardness, 150 ± 12.32 GPa elasticity modulus, and 802 ± 21 MPa yield strength) than (6.25 ± 0.52 GPa nano-hardness, 159 ± 14.21 GPa elasticity modulus, and 850 ± 19 MPa yield strength) of TA-graphene-silver (TAGS). Multilayer graphene nanosheets were curled into small loops to resist the applied forces, and helped to improve the mechanical properties of the TAGS. Subsequently, the graphene nanosheets enhanced the tribological performances as observed by the ball-on-disk tribometer. The following factors were primarily responsible for more excellent tribological behaviors (approximately 0.27 friction coefficient, 2.82 × 10−4 mm3 N−1 m−1 wear rate) of TAGS than those of the TAG: intra-lamellar separation of graphene, graphene-enhanced capacity of wear scar, plastic deformation of silver, the excellent cooperation lubrication of graphene-silver, the low-hardness lubrication film on the grain-refined layer, the well-distributed film grain, and low grain orientation angles.