Tension/compression asymmetry of grain boundaries with non-planar structure

Molecular dynamics simulations were carried out to investigate the mechanical property and the

deformation mechanisms of Cu bicrystal with non-planar structured grain boundaries(GBs) under

uniaxial tension and compression. The simulation results showed that the non-planar GBs could

change their equilibrium configurations under the applied stress, and the deformation mechanisms

varied when altering the misorientation angle. The stacking fault energy curve was affected by the

stress perpendicular to the slip plane and therefore has an influence on the dislocation nucleation

mechanisms. Previous studies have revealed a ubiquitous tension/compression (T/C)strength

asymmetry of many ultra-fine or nanocrystalline materials, and a higher compressive strength was

usually reported. However, in the present study, the bicrystal samples with non-planar structured GBs

show a higher tensile strength than the compressive one. The unusual T/C asymmetry property has an

implication that the GBs with non-planar structure can play a significant role in affecting the

mechanical properties of nanostructured materials.