Atomistic simulations of tungsten nanotubes under uniform tensile loading

Nanotubes (NTs) are generally lighter than nanowires (NWs) and can possess equal or greater strength, despite this, body-centered cubic (BCC) NTs have been scarcely studied. In this work, molecular dynamics simulations are performed to investigate the tensile loading of BCC tungsten NTs and NWs. NTs (of various thicknesses) and NWs with outer radii 5 nm, 10 nm, 15 nm, and 20 nm are uniformly stretched at 300K in the <100>, <110>, and <111> directions, respectively. Our simulations show that some NTs possess higher yield stress and yield strain than their NW counterparts. Specifically, (i) NTs with 5 nm outer radius exhibit consistently superior strength across examined thicknesses -- maximums being a 40% increase in yield stress and 5% increase in yield strain compared to the NW with the same outer radius; (ii) NTs oriented along <100> have consistently higher yield strains compared with the corresponding nanowires; (iii) when the experimental temperature is set at 800K, there is an increase in Young’s modulus for all orientations and a ductile brittle-transition in the 15 nm NW case.