Molecular dynamics study of corrosion behavior of iron with vacancies exposed to lead-bismuth eutectic

LM Chen and S Xu and XX He and QL Cao and BS Li, MATERIALS AND CORROSION-WERKSTOFFE UND KORROSION, 74, 793-802 (2023).

DOI: 10.1002/maco.202213375

The corrosion behavior of iron with vacancies in a liquid lead-bismuth eutectic environment is simulated by molecular dynamics with embedded- atom model potential at 700-1073 K. The vacancy is substituted into Fe crystal with the percentage of 0%, 0.2%, 0.4%, 1.0%, and 2.0% to investigate the effect of the vacancy on the corrosion behavior of iron. By evaluating the time-dependences of penetration depths and the number of penetrating Pb and Bi atoms and also observing the trajectory of a penetrating Bi atom, we concluded that temperature and vacancy will enhance the corrosion behavior of iron in liquid lead-bismuth, and the corrosivity of Bi atom is larger than that of Pb atom. The result is supported by the calculated substitutional energies of each Pb or Bi atom with a Fe atom or vacancy, which are in the order of EvacBiE_\rmv\rma\rmc<^>\rmB\rmi\lt E_\rmv\rma\rmc<^>\rmP\rmb\lt E_\rmF\rme<^>\rmB\rmi\lt E_\rmF\rme<^>\rmP\rmb$. If there are vacancies in the iron bulk, the Bi atom and Pb atom will preferentially penetrate the bulk through the vacancies, and the Bi atom has another way to penetrate into the bulk by substituting the Fe atom layer by layer. The present study provides new insight into challenges related to the corrosion behavior of iron-based materials with vacancy-type defects.

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