Atomistic Simulation of the Orientation-dependent Plastic Deformation Mechanisms of Iron Nanopillars

Tensile tests were performed on iron nanopillars oriented along [001] and [110] directions at a constant temperature of 300 K through molecular dynamics simulations with an embedded-atom interatomic potential for iron. The nanopillars were stretched until yielding to investigate the onset of their plastic deformation behaviors. Yielding was found to occur through two different mechanisms for [001] and [110] tensions. In the former case, plastic deformation is initiated by dislocation nucleation at the edges of the nanopillar, whereas in the latter case by phase transformation inside the nanopillar. The details during the onset of plastic deformation under the two different orientations were analyzed. The varying mechanisms during plastic deformation initiation are bound to influence the mechanical behavior of such nanoscale materials, especially those strongly textured.