Molecular dynamics simulations of void shrinkage in γ-TiAl single crystal

Molecular dynamics simulation was performed to study the shrinkage of spherical nano-void under uniaxial compression load in gamma-TiAl single crystal. During the compression, the nano-void crystal undergoes elastic then plastic deformation process. In the elastic period, the nano-void shrinks linearly along compression direction while it expands linearly along the directions perpendicular to the compression direction. Finally, the nano-void collapses from all directions at the beginning of the plastic process. The formation and extension of dislocations and the shrinking mechanism of void were analyzed in detail. The dependence of the void shrinking on the specimen size, strain rate, and void volume fraction were also investigated. It is found that the stacking faults' slipping in the crystal during plastic period is the main deformation mechanism of the void shrinkage: dislocation structures initially start to nucleate around the equator area of the void, then partial dislocations and planar faults constantly propagate, finally the stacking faults and partial dislocations swap through the entire system and the void shrinks. (C) 2015 Elsevier B.V. All rights reserved.