Theoretical study on the alloying behavior of -uranium metal; -uranium alloy with 3d transition metals

ウラン金属の合金化挙動に関する理論的研究; 3d遷移金属のウラン合金

栗原 正義*; 平田 勝 ; 関根 理香*; 尾上 順*; 中松 博英*

Kurihara, Masayoshi*; Hirata, Masaru; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*

相対論DV-DFS分子軌道法を用いて3d遷移金属の相ウラン合金の合金化挙動を調べた。d軌道エネルギー(Md)の値は、ウラン合金化挙動と良好な相関があることがわかった。すなわち、Ti, V, Crのように相ウランに固溶しやすい金属は比較的高いMd値を持つ。逆にCuのように全く固溶しない金属は、非常に低いMd値を取ることがわかった。

We have investigated the alloying behavior of g-uranium with 3d transition metals (TMs) using the relativistic discrete-variational Dirac-Fock-Slater (DV-DFS) method. The d-orbital energy (Md) as an alloying parameter well reproduces the alloying behavior of g- uranium metal with TMs: (1) in the case of a large Md value (Ti,V,Cr), the solubility of these TM elements in g-uranium becomes large; (2) in the case of a middle Md value (Mn,Fe,Co), the tendency to form a uranium intermetallic compound with these elements becomes stronger; (3) in the case of a small Md value (Cu), the alloying element is insoluble in g-uranium. The alloying behavior of g-uranium with TMs is also discussed in terms of other parameters such as electronegativity and metallic radius.