Investigation of Grain Boundary Content on Crack Propagation Behavior of Nanocrystalline Al by Molecular Dynamics Simulation

QH Li and ZB Dong and SZ Zhou and F Han and CK Li and H Chang and ZP Zhang, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 259, 2100570 (2022).

DOI: 10.1002/pssb.202100570

The nanocrystalline metal material has been an investigation hotspot due to its excellent mechanical property. The high content of grain boundaries (GBs) in microstructure is the key factor affecting its fracture behavior during service. Therefore, it is essential to investigate the effect mechanism of nanoscale GB on crack propagation. In this study, four molecular dynamics (MD) models of nanocrystalline aluminum (Al) with different GB contents are established. The results show that the high-content GBs in polycrystals can increase the toughness and absorb energy, reducing the risk of brittle crack propagation. The presence of GB can reduce the stress concentration of the crack, and the dislocation emission from the crack tip can be absorbed by the front GB. The microstructure with high-content GBs can actuate more plastic deformation mechanisms such as multiple slips, GB slip, and migration. The region with more GBs can induce a more even deformation of the whole microstructure by means of dislocation emission and GB migration to the region with fewer GBs. The purpose of this study is to provide a rational mechanism reference for the failure of nanocrystalline metal material.

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