Molecular dynamics simulations of dynamics mechanical behavior and interfacial microstructure evolution of Ni-based single crystal superalloys under shock loading

Abstract

In this paper, molecular dynamics simulations are performed to study the dynamic mechanical response and microstructural evolution of Ni-based single crystal superalloys under different shock velocities. The results show that when the shock velocity (Up ≤ 0.75 km/s), the interfacial dislocation network composed of the Stair-rod dislocation will prevent the Shockley dislocation from shearing the γ′ phase, the deformation of the microstructure is dominated by the slipping and dragging of dislocations. When the shock velocity (Up ≥ 1 km/s), the interfacial dislocation network is destroyed under the shock loading, the dislocations basically disappear, the atomic structure becomes disordered and undergoes structural phase transformation. In addition, the increase of the shock velocity leads to the regular increases of the shock pressure, internal energy and normal stress of the superalloys. However, the shear stress increases sharply once the shock velocity is greater than 1 km/s due to the change of the microstructural deformation mechanism. This work has an important guiding significance for in-depth understanding of the failure mechanism of Ni-based single crystal superalloys under shock loading.

Keywords

• Ni-based single crystal superalloys
• Shock loading
• Dislocation evolution
• Dynamic mechanical response
• Molecular dynamics simulation