Study on atomic-scale deformation mechanism based on nanoindentation of duplex full lamellar TiAl alloys with different orientation relationships

The effect of the orientation relationship between gamma and alpha 2 phases on the mechanical properties and microstructural evolution in duplex full lamellar TiAl alloys is investigated by the nanoindentation technique using molecular dynamics (MD) simulation method. In this paper, we construct separately the Blackburn orientation relationship: ⟨1-10⟩gamma parallel to⟨11-20⟩alpha 2 and {111}gamma parallel to(0001)alpha 2, the Parallel orientation relationship: [010]gamma parallel to[1-210]alpha 2 and (001)gamma parallel to(0001)alpha 2 as well as the Vertical orientation relationship: [001]gamma parallel to[1-210]alpha 2 and (100)gamma parallel to(0001)alpha 2 these three models. The results show that the effect of different orientation relationships cause variability in the fluctuation amplitude and magnitude of force, the accumulation shape and area of surface morphology, the atomic displacement, and the temperature on the substrate during the indentation process. The hardness and the modulus of elasticity for the alloys vary according to the orientation relationships, with the Blackburn orientation relationship having the highest hardness and modulus of elasticity, the Parallel orientation relationship having the lowest modulus of elasticity, and the Vertical orientation relationship having the lowest. The amount of deformation and defect evolution of the substrate during the indentation process are also affected by the orientation relationships, with the Blackburn orientation relationship model producing the most defects, the Vertical orientation relationship the next most, and the Parallel orientation relationship being the least.