Atomic Simulation of Crystallographic Orientation Effect on Void Shrinkage and Collapse in Single-Crystal Copper under Shock Compression

M Wang and YQ Zhang and SY Jiang, JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE (2021).

DOI: 10.1007/s11665-021-06438-0

Molecular dynamics simulations were performed to study the evolution of void along different crystallographic orientations of single-crystal copper under shock compression, including 1 (1) over bar0, 111 and 100 orientations. For both 1 (1) over bar0 and 111 directions, the void only shrinks and does not collapse, whereas for 100 direction, the void can gradually shrink until it collapses completely. Dislocations react with each other to form sessile dislocations during the continuous loading of the shock waves, in both 1 (1) over bar0 and 111 directions, and almost all the dislocations are found to be a/6 < 110 > stair-rod partial dislocations which are of sessile type. However, for the 100 orientation, sessile dislocations are mainly a/3 < 001 > Hirth partial dislocations. For 100 direction, the sessile dislocation density is the lowest among the three orientations. Therefore, shock compression along 100 direction is more conducive to plastic deformation of the void. Dislocation slip is responsible for deformation mechanism of the void, where a/6 < 112 > Shockley partial dislocations are firstly generated on the surface of the void, and then they continue to move and multiply, which shall lay the foundation for the formation of stacking faults. Stacking faults sweep through the crystal plane and consequently the void shrinks. This work gives an atomic-scale observation perspective of the evolution of micro-void defects in single-crystal copper under shock compression and provides a clearer explanation for the understanding of the dislocation evolution mechanism behind the deformation.

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