The intricate relationship between the cooling rate, atomic structure, and mechanical properties of the refractory metal Ta

Abstract

In this study, molecular dynamics (MD) simulations were performed to investigate the relationship between cooling rate, atomic structure, and mechanical properties of the refractory metal tantalum (Ta). Analysis of the minimum of the first trough (g_min) and the maximum of the first peak (g_max) in the radial distribution function (RDF), as well as their ratio (R = g_min/g_max), revealed that the temperature evolution of the g_min alone is sufficient to accurately distinguish the transitions between supercooled liquid, amorphous, and crystalline states. This constitutes the key innovation of the present work. Furthermore, the distribution of atomic clusters under different cooling rates indicates that the enhanced mechanical properties of the crystalline sample quenched at γ₂ = 1 × 10¹¹ K s⁻¹ are attributed to the formation of numerous chain-linked icosahedral clusters. While crystalline Ta exhibits higher ultimate tensile strength than its amorphous counterpart, it shows significantly lower fracture toughness. Additionally, the presence of impurities such as oxygen, hydrogen, and water vapor were found to significantly influence the final microstructure during rapid solidification, highlighting the importance of maintaining high-vacuum conditions to achieve controlled solidification and desirable material properties.