Atomistic simulations of mechanical characteristics dependency on relative density, grain size, and temperature of nanoporous tungsten

Abstract

A series of atomistic simulations are adopted to explore the influences of relative density, grain size, and temperature on the tensile characteristics of nanoporous tungsten (NPW). Results illustrate that the dominant mechanism of deformation for monocrystalline NPW is the combination of twin boundaries (TBs) migration and 1/2<111> dislocation movement. The relative density, which has a positive relationship with stiffness and strength, significantly affects the mechanical properties of NPW. With relative density growing from 0.30 to 0.60, Young's modulus, UTS, and yield strength of monocrystalline NPW increase from 18.55, 0.65, and 0.45 GPa to 93.78, 2.93, and 2.59 GPa, respectively. Young's modulus and relative density have a quadratic relationship, meaning that the dominant deformation is the bending deformation of ligaments during the elastic stage. The scaling law for yield strength reveals that the axial yielding of ligaments dominates the yielding behavior of NPW. The relationship between mean grain size (5.00 ~ 17.07 nm) and strength follows the reverse Hall-Petch relation. Besides, the effect of temperature on mechanical characteristics is discussed. With the increase of temperature from 10 K to 1500 K, Young's modulus of monocrystalline NPW and nanocrystalline NPW (d = 5.00, 10.99, and 17.07 nm) decrease from 69.24, 51.73, 61.08, and 63.75 GPa to 48.98, 34.77, 44.65, and 49.05 GPa. The findings systematically reveal the mechanical properties of NPW under tension and provide guidance for its application.

Size effects in molecular dynamic simulations of fracture in bcc iron crystals

“…Generally, twinning play very important role in mechanical properties of the bcc metals -see e.g. [25]. The results presented above illustrate that MD simulations can bring new information on microscopic processes generated by the crack itself.…”

Enhancing surface strength of tungsten by gradient nano-grained structure

“…Tungsten is a refractory metal with exceptionally high strength, hardness, and high melting point. [1][2][3][4][5] When it comes to hightemperature components such as plasma-facing walls and diverters, 6,7 tungsten has showcased its potential utility in fusion reactors. Additionally, it is a promising spallation target in accelerator-driven subcritical clean nuclear energy systems.…”

“…Hu et al 12 conducted molecular dynamics simulations to investigate the effects of grain size, indenter velocity, indenter size, and temperature on the indentation characteristics of tungsten metal. Hu et al 4 employed a series of atomistic simulations to explore the influences of relative density, grain size, and temperature on the tensile properties of nanoporous tungsten, demonstrating the critical role of relative density in mechanical performance, with different deformation mechanisms arising from variations in grain size and relative density. Additionally, research has been conducted on tungsten metal matrix composites, where Hu et al 5 proposed five different graphene/tungsten nanocomposites and employed molecular dynamics to study the mechanical properties and microstructural evolution of these nanocomposites.…”