Effect of crystal orientation on the size effects of nano-scale fcc metals

Abstract

The present work investigates the dominant mechanisms in the plasticity of nano-sized fcc metallic samples. Molecular dynamics simulations of nanopillar compression show that plasticity always starts with the nucleation of dislocations at the free surface, and the crystal orientation affects the subsequent microstructural evolution. The Schmid factor of leading and trailing partials plays a decisive role in leading to the twinning, or slip deformation. A significant difference is observed in the strength of pillars of the same size with different orientations. The power-law equation exponent is completely dependent on the crystal orientations, and a weak or no size effect is observed in the compression of [100]- and [110]-oriented nanopillars. The observed orientation based behaviour decreases by confining the free surface.

KEYWORDS:

• Size effects
• Plasticity
• Dislocations starvation
• Twinning
• Slip
• Surface effect
• Crystal orientation
• Molecular dynamics simulation

Acknowledgements

The authors wish to acknowledge the financial support for this research from the Natural Sciences and Engineering Research Council of Canada (NSERC) under the Discovery Grant program. The authors also acknowledge Compute Canada (www.computecanada.ca) for providing the computational time necessary for this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada.