Effect of γ/α 2 Phase Interface on Supersonic Fine Particle Bombardment of TiAl Alloy by Molecular Dynamics Simulation

Abstract:

In order to investigate the effect of γ/α₂ phase interface on the deformation mechanism and mechanical properties of TiAl alloy during bombardment process, the supersonic fine particle bombardment of dual-phase TiAl alloy was simulated by molecular dynamics. Results show that the impact deformation mechanisms of γ/α₂ models with different thickness ratios are different, and the deformation is mainly concentrated at the γ phase and interface. With decreasing the γ phase thickness, the dislocations in contact with the phase interface are firstly absorbed by the mismatched dislocation network, then they are nucleated at the phase interface, and eventually the dislocations pass through the phase interface, entering the α₂ phase. Shockley dislocation is the main dislocation type in the impact process, and incomplete stacking fault tetrahedron forms in the specimen. After impact, uniaxial tensile simulation and nano-indentation simulation were conducted to measure the strength and surface hardness of the specimens. The main deformation mechanisms of specimens with different thickness ratios are the phase transformation, twins, and stacking faults during tensile process. Compared with other specimens, TiAl alloy with thickness ratio of 1:3 has the highest yield strength, the highest hardness, and the highest elastic modulus after impact.

Key words:molecular dynamics;phase interface;TiAl/Ti₃Al;mechanical properties;plastic deformation