Atomic simulation on the effect of twin boundary angles on the mechanical properties of TiAl alloys under supersonic fine particles bombardment

Abstract TiAl alloys have been widely adopted in aerospace due to their exceptional mechanical properties. However, surface defects such as cracks and voids that develop during service significantly compromise component longevity. To enhance surface mechanical performance, this study employs supersonic fine particle bombardment (SFPB) to treat TiAl alloys with varying twin boundary angles, systematically investigating post-treatment deformation mechanisms, tensile properties, and indentation characteristics. Findings demonstrate that twin boundary angles significantly influences the mechanical properties of SFPB-treated TiAl alloys. The 0° specimen exhibits the highest yield strength, while the 30° specimen achieves maximum hardness. Surface analysis reveals that the 30° specimen undergoes the least severe plastic deformation following SFPB treatment. The tensile deformation mechanisms involve: dislocation motion, dislocation-twin boundary interactions, and vacancy evolution. The 60° specimen fractures along the twin boundaries, where the formation of secondary twins and stacking fault tetrahedrons during deformation effectively retards crack propagation. In contrast, other specimens fracture at the surface. Nanoindentation analysis confirms that dislocation-twin boundary reactions dominate the deformation behavior across SFPB-treated specimens. These results demonstrate that controlled adjustment of twin boundary angles provides an effective approach for tailoring the mechanical properties of TiAl alloys processed by SFPB, offering valuable theoretical guidance for practical engineering applications.