Molecular Dynamics Simulation of Tensile Deformation Behavior of Monocrystalline Ni and Its Alloys with Different Stacking Fault Energies

JJ Chen and YT Ding and YJ Ma and YB Gao and XM Wang, RARE METAL MATERIALS AND ENGINEERING, 52, 3198-3209 (2023).

The uniaxial tensile deformation of monocrystalline Ni and Ni57Cr19Co19Al5 alloy models with different cross-sectional size models in the 100 orientation was simulated by molecular dynamics, and the appropriate simulation model size with stable plastic flow stress was determined. The tensile deformation behavior of monocrystalline Ni and its alloys of the same model with stable flow stress were further studied. The results show that the monocrystalline Ni57Cr19Co19Al5 alloy with smaller model sizes are likely to form multi-layer twins or deformation twins during the tensile process because of low stacking fault energy. As the cross-sectional side length of model is greater than 30 times of lattice constant, the fluctuation of the flow stress, phase structures and dislocation density in the plastic flow stage tends to be stable with the variation of strain. When the monocrystalline Ni and Ni-based alloys with same model at stable flow stress stage are stretched, the lower the stacking fault energy is, the larger the area of the stacking faults plane during plastic deformation. During the tensile process of monocrystalline Ni and Ni-based alloys, Shockley partials play a leading role in the plastic deformation process. The formation of multi-layer twins is accompanied by dislocation exhaustion, while the formation and annihilation of deformation twins are mainly dominated by the dislocation starvation mechanism.

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