Impact of γ/α2 phase and interface on the wear of biphasic titanium-aluminum alloys under lateral vibration friction

The effect of wear balls on the material under transverse periodic vibrational friction of the γ-TiAl and α₂-Ti₃Al phases was investigated on an atomic scale employing molecular dynamics simulations. Mechanical performance, temperature, atomic displacement, shear strain, and dislocation density of biphasic titanium-aluminum alloys were systematically analyzed. It is found that when the wear ball passes through the γ/α₂ interfaces it causes the structure of the interface to be damaged, resulting in a weakening of the reinforcement of the interface. At this point, the total force applied at the interface decreases accordingly. However, the existing boundary between the two phases prevents the movement of atoms and the transfer of stresses. The deepness of the abrasion marks for the α₂-phase during friction is smaller than for the γ-phase, due to the great resistance to slip of dislocations in the α₂-phase, which makes it difficult to drive the deformation in all directions. Dislocations first nucleate at the interface, and the evolution of dislocations in the α₂ and γ-phases leads to energy accumulation and release from the γ/α₂ interfaces. The increase in the density of dislocations in the γ-phases is significantly greater than that of the α₂-phases, so the stacking of dislocations in the γ-phases will improve the distortion resistance of the material as a whole.