The influence of lamellar twins on deformation mechanism in nanocrystalline magnesium under uniaxial compression

Abstract

Molecular dynamics simulation is employed to investigate the deformation mechanism of nanocrystalline (NC) Mg with lamellar $$ \{ 1 0 {\bar{\text{1}}\text{1}}\} $$ twins. Five models including a twin-free model and four nanotwinned models with increasing twin boundary (TB) spacing from 2.5 to 20 nm are simulated under uniaxial compressive strain rate of 1 × 108 s−1 at 300 K. Compared with notwinned NC Mg, the introduction of lamellar twin structure can decrease the strength that behaves as a softening mechanism due to the migration of initial TB and newly formed twins. The strength decreases with the reduction in TB spacing. In addition, the model with TB spacing of 2.5 nm is also simulated under uniaxial compression at 0.01 K and 500 K in order to study the effect of temperature. The result shows that the compressive stress increases as the temperature decrease due to the promotion of grain boundary motion and TB migration.