Micro Defects Evolution of Nickel-Based Single Crystal Superalloys during Shear Deformation: A Molecular Dynamics Study

Nickel-based single crystal superalloys have become the main structural materials of the aero-engines due to excellent high-temperature strength. The micro defects evolution of nickel-based single crystal superalloys under shear deformation was investigated by molecular dynamics (MD) simulations in the present study. It is found that the interfacial dislocations decompose into Shockley dislocations under low shear stress, resulting in the plastic deformation of the Ni phase. The initial plastic deformation of the Ni₃Al phase is caused by Shockley dislocations cutting into the Ni₃Al phase. The following deformation from low temperature to medium temperature is controlled by dislocation slip, but the deformation at high temperature is changed. It is also found that the microvoid evolution can be divided into void growth and coalescence during shear deformation. The microvoid could prevent dislocation entanglement, accelerate dislocation decomposition, and promote earlier plastic deformation under relatively low temperatures.