Abstract

Twin boundaries are known for their strengthening influence and elevation of ductility in metallic nanopillars. They function both as a source of dislocation nucleation and as impediments to dislocation mobility. This study employs molecular dynamics simulations to examine the tensile properties, specifically strength, and ductility, of a twinned Al nanopillar featuring a horizontally orientated [111] twin boundary subjected to uniaxial tensile loading. Five models were constructed using Atomsk by varying the number of twin boundaries ranging from 1 up to 7, and an additional Al sample free of twins was also created to compare the changes in twin boundaries. The tensile deformation was performed at the room temperature using a constant strain rate of 10^10 s^(-1) for 30 ps. From the results, the ultimate tensile strength of Al without twins was 5.72 GPa, whereas UTS increased in each model and stood at 5.91 GPa in the 7-twin model, an almost 3.5% increase. Though the yield strength peaks at 4.17 GPa in the no twin model and reaches its lowest at 1.85 GPa in the 7-twin model. The findings indicated that reduced inter-twin spacing resulted in reduced yield strength, elucidating the anomalous Hall-Petch relationship. The post-processing of the simulation data was conducted by dislocation extraction analysis (DXA) provided by OVITO.