Annealing effect on elastic and structural behavior of Tantalum monatomic metallic glass

Abstract

Molecular dynamics simulation with embedded atom method (EAM) interatomic potential has been devoted to investigating the elastic and structural behavior of Tantalum (Ta) monatomic metallic glass (MG). Ta-MG samples were heat treated for periods ranging from 0 to 10 ns at three aging temperatures (500 K, 900 K and 1100 K). Our results revealed an improvement in terms of elastic constants C11 and C44, and a reduction of C12 when annealing time and temperature increase. During annealing process, the Ta monatomic MG undergoes a hardening and its yield strength increases. This has been correlated to the increase of Young's modulus (E) and shear modulus (G) which suggests the improvement of the elastic behavior and the resistance to the shear bands (SBs), respectively. We found that during aging process, the isotropic property of Ta monatomic MG remains invariants. The self-diffusion coefficient (D) has been found to be more pronounced at 1100 K near the glass transition temperature, which leads to an atomic vibration by reducing the amount of free volume accumulated during the glass transition and inhibits the localization of certain defect such as shear bands (SBs). We have also found that the <0,0,12,0> full icosahedral short-range order (SRO) increases as annealing time increases. At medium-range order (MRO), the full icosahedral cluster <0,0,12,0> has been observed to be connected by intercross-sharing (IS), face-sharing (FS), Edge-sharing (ES) and vertex-sharing (VS). These enhancements in structural properties are the principal key to interpret the achieved hardening of Ta monatomic glass under annealing process.