Abstract：The nanoindentation cyclic deformation behavior of single crystal NiTi shape memory alloy films are simulated using the second nearest neighbor modified embedded atomic potential molecular dynamics method, and the effect of temperature on the microstructure evolution is mainly discussed. To further reveal the plastic deformation mechanism of single crystal NiTi shape memory alloy films, the effects of martensitic phase transformation, dislocations, disordered structure and elastic recovery coefficient involved in indentation are analyzed. The simulation results show that a critical load of steep drop in load-displacement curves at different temperatures (350K, 450K, 550K) is different, which is mainly related to the nucleation of dislocations. Increasing temperature can promote the nucleation and slip of dislocations, resulting in a decrease in resistance to plastic deformation. In addition, the superelastic cyclic deformation can reach stability after a certain number of cycles, and there is a correlation between plastic deformation and crystal structure evolution. The accumulation of nanoindentation residual deformation originates from dislocation slip, twinning deformation, residual martensite phase accumulation and disordered structural plasticity.
2023, Vol. 44 
