Comparison of the primary damage states in iron and nickel by molecular dynamics simulations

Abstract

A displacement cascade formation in bcc-Fe and fcc-Ni has been investigated by using molecular dynamics (MD) simulations and improved many-body interatomic potentials. To assure the statistical validity of the calculation, multiple simulations are required at identical conditions. Six cascade simulations were run in the following two cases, with simulation energies of 3.5 keV at 100 K and 4.1 keV at 570 K. The cascade simulations for bcc-Fe were carried out by using the MOLDY code and the interatomic potentials developed by Finnis and Sinclair, whereas those for fcc-Ni were conducted by using the MDCASK code and the embedded-atom method potentials. The MD calculations demonstrate that the atomic configurations of the primary damage state are similar in Fe and Ni. However, the bcc-Fe displacement cascade produced more residual defects than the fcc-Ni cascade. In addition, various sizes of interstitial clusters are observed in Ni. As these parameters have important implications for the assessment of a radiation damage to materials, we derived the primary damage parameters for a future use in the kinetic models.

Keywords:

• Displacement cascade
• Molecular dynamics
• Interatomic potentials
• Primary damage

Acknowledgements

The authors gratefully acknowledge Dr. R.E. Stoller of ORNL and Dr. J. Shim of KIST (Korea) for providing the MOLDY and MDCASK codes, respectively. The authors would like to thank the Korean Ministry of Science and Technology for the promotion and sponsorship of the research work under ‘National mid- and long-term atomic energy R&D program’.