Simulations of Nanocrystalline Iron Formation under High Shear Strain

• Main Authors: Tolkachev, Ivan, Ma, Pui-Wai, Mason, Daniel, Hofmann, Felix
• Format: Journal Article
• Language: English
• Published: 29-09-2023
• Subjects: Physics - Materials Science
• DOI: 10.48550/arxiv.2309.17090

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 {\gamma} = 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.