[1] Japan Atom Energy Agcy, Tokai, Ibaraki 3191195, Japan
[2] Kyoto Univ, Inst Adv Energy, Kyoto 6110011, Japan
[3] Osaka Univ, Joining & Welding Res Inst, Osaka 5670047, Japan
[4] Muroran Inst Technol, Dept Mat Sci & Engn, Muroran, Hokkaido 0508585, Japan
[5] Osaka Univ, Div Mat & Mfg Sci, Suita, Osaka 5650871, Japan
[6] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA