Chemical origin of differences in steel corrosion behaviors of s-electron and p-electron liquid metals by first-principles calculation.

Abstract

Steel corrosion is a key engineering issue in the development of advanced nuclear reactors using liquid metals. The present study demonstrates that the steel corrosion behaviors can be systematically understood and classified based on the types of valence electrons of liquid metals, namely, s-electron liquid metals (s-LMs), such as liquid Na and Li, and p-electron liquid metals (p-LMs), such as liquid lead-bismuth eutectic (LBE) and Pb, where the conduction band is composed of s and p valence electrons, respectively. Through a comparative analysis of the physiochemical states of 3d transition metal atoms dissolved in liquid Na and liquid LBE by means of first-principles molecular dynamics (FPMD), it is shown that the 3d and 4s orbitals of the transition metals hardly interact with the s band of s-LMs, while they strongly interact with the p band of p-LMs in a covalent manner. This fact is consistently seen in the electronic states and the atomic configuration and can be successfully used to explain the differences in the steel corrosion behaviors observed between the liquid metals by experiments. The present findings provide fundamental insights into the corrosion chemistry of liquid metals.