1930 鉛ビスマス流れによる鋼材の腐食現象に関する研究

Abstract

The corrosions of structure materials such as stainless steel in liquid Pb-Bi metals are a big obstacles for the application of the liquid Pb-Bi into the fast breeder reactors as the coolants. The present work is trying to seek the atomic mechanism of the corrosion phenomena from the point-of-view of interatomic interactions. The interatomic potential energies are calculated by the ab initio method vs. interatomic distance. From the interatomic potential energies, it is cleared that Fe atoms in the pure perfect iron crystals don’t diffuse mutually with liquid Pb-Bi atoms. However, Pb atoms may penetrate into the void sites of the crystals of iron through grain boundaries as that the attractive forces from Fe are larger that that from Pb-Bi atoms. Thus, the very small solubility of Fe in liquid Pb-Bi metals may be due to the crystal defects or some accidental reasons. In SUS316, as the larger cohesive forces between Ni and Pb, Bi atoms, t he corrosions of SUS316 in liquid Pb -Bi metals are mainly caused from the mutual diffusions between Ni and Pb-Bi atoms. Also, as the attractive forces from Cr atoms, Pb atoms are easily to penetrate into the SUS316 in addition to the attractive forces from Fe atoms. As a result, with the time evolving, Ni and Cr atoms dissolve gradually into the liquid Pb-Bi metals, while Pb and Bi atoms penetrate into the solids gradually. The corrosion test results verify very well the analytical results based on the calculated interatomic potential energies..