Effect of Lithium Purity on In-Situ Formation of Er₂O₃ Oxide Layer on V-4Ti-4Cr Alloy

抄録

Effect of Li purity with respect to N on the features of in-situ formation of Er₂O₃ oxide coating on the surface of V-4Ti-4Cr alloy was investigated. Samples of V-4Ti-4Cr alloy (NIFS HEAT 2) were pre-charged by oxygen in Ar-7%O₂ at 700^◦C. The hardened zone with needle shaped Ti-O net structure was formed in the near-surface layers of V-alloy after oxidation. Oxygen pre-charged samples were exposed to N-containing Li (C_N[Li] ≤0.2 wt%) at 700^◦C and Li pre-cleaned by getter (Zr) at 650^◦C for 100 h. Both melts were doped with active Er impurity. It was shown that in-situ formation of E₂O₃ oxide coating on the surface of V-alloys depends strongly on the purity level of Li with regard to the N. In N-containing Li the coating was not formed on the surface of V-alloy, while whole oxygen pre-stored in V-matrix was dissolved by Li. On the contrary, in Li pre-cleaned with respect to N by Zr getter, the insulating oxide film was formed.