The effect of shock velocity and defects on laser shock peening of single crystal copper: A molecular dynamics research

YY Wang and XB Jing and ZZ Kuai and B Liu, MATERIALS TODAY COMMUNICATIONS, 47, 112982 (2025).

DOI: 10.1016/j.mtcomm.2025.112982

In order to further improve the properties of parts formed by selective laser melting (SLM), post-treatment of the parts has become an important improvement approach. The laser shock peening (LSP) has been demonstrated in improving the comprehensive properties of metal materials and its application achievements in the field of additive manufacturing. In this work, the molecular dynamics method is used to study the mechanisms of microstructure evolution of single crystal copper under different shock velocities and defect types during LSP process. The results indicate that the deformation mode of single crystal copper undergoes three main period with the increase of shock velocity: the elastic deformation stage, the elastic and plastic deformation stage, and the plastic deformation stage. The phase transition from FCC to BCC and the phase transition from BCC to HCP are discovered during plastic deformation, which follow the Bain and Burgers mechanisms, respectively. When the shock velocity is extremely fast (Up=1.5 km/s), the formation of twin crystals (1012)1011 is observed. The structure of shock waves is transformed due to the presence of defects, leading to "reflection unloading" or "reflection loading". In addition, the defects also affect atomic movement and stress distribution, thereby affecting the propagation speed of shock waves in the copper matrix.

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