Atomic-scale investigation on fretting wear mechanism of γ phase in a cast Ti-45Al alloy

The atomic-scale investigation on fretting wear mechanism of gamma phase in a cast Ti-45Al alloy was conducted. The fretting wear of the alloy at 25 degrees C was a mixture of abrasive and adhesive wear. The results showed that serrated waves were observed in the force-time curves, which was associated with the local welding between the abrasive particles and substrates when fretting wear occurred. The main plastic deformation mechanism was mechanical twinning in the substrates. The introduction of order-twin (RT) interfaces restricted the downward movement of abrasive particles. The twinning across lamellae was dominant in the substrates with a RT lamella. Dislocation pile-ups in RT interfaces induced the formation of twin embryo. The successive dislocation dissociation 1/6[12 - 1]-> 1/6[011] + 1/6[-11 - 2] was the nucleation mechanism of twinning across lamellae.