Simulations of Nanocrystalline Iron Formation under High Shear Strain

Abstract

High-shear methods have long been used in experiments to refine grain structures in metals, yet the underlying mechanisms remain elusive. We demonstrate a refinement process using molecular dynamic simulations of iron, wherein nanocrystalline structures are generated from initially perfect lattices under high-shear strain. The simulation cells undergo a highly disordered state, followed by an atomic reordering and grain coarsening, resulting in nanograins. We explore the dependence on parameters such as temperature, heat dissipation rate, shear strain rate, and carbon impurity concentration. Higher temperatures lead to the formation of larger and longer grains. The faster heat dissipation sample initially yields more small grains, but their number subsequently reduces, and is lower than the slower heat dissipation sample at approximately γ = 1.5. Slower strain rates do not promote nanograin formation. The presence of carbon impurities appears to have little effect on grain formation. This detailed analysis affords insight into the mechanisms that control the formation of nanograins under high-shear conditions.

References in corpus (6)

• Robust Structural Identification via Polyhedral Template Matching
• Development of an interatomic potential for phosphorus impurities in iron
• Probing the ultimate limits of metal plasticity
• Molecular Dynamics Simulations of Compression-Tension Asymmetry in Plasticity of Fe Nanopillars
• Parameter-free quantitative simulation of high dose microstructure and hydrogen retention in ion-irradiated tungsten
• Incorporating non-adiabatic effects in Embedded Atom potentials for radiation damage cascade simulations