Process-induced evolution of prismatic dislocation loop and its effect on mechanical properties

Titanium aluminum alloy is widely used in aerospace, automotive engines and other fields, the attention of microstructure and mechanics of the machined workpiece can make it have better service performance. This paper constructs a molecular dynamics model that better fits with the actual nano-cutting of single crystal gamma-TiAl alloy. The formation of the sub-surface defect layer in the nano-cutting process is analyzed, and the evolution mechanism of the material sub-surface prismatic dislocation loop is discussed in detail. In addition, the nano-indentation simulation is carried out on the surface of the material with prismatic dislocation loop structure to study the effect of process-induced sub-surface defect structure on the mechanical properties of the material. The simulation results show that the existence of Stair-rod dislocation in the prismatic dislocation loop hinders the slip of stacking fault. The nanoindentation process will release the residual stress in the material and make the material have a certain degree of elastic recovery. The original defect structure will increase the hardness of the material, which verifies the work hardening phenomenon of the machined surface caused by the internal defects of the material.