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2008/04/08(Tue) 13:33

Enhancement of Jc and Bc2 by Prebending Treatment on Bronze Route Nb3Sn Wires

We found that all of Jc, Bc2 and Tc are much enhanced for bronze route Nb3Sn wires by the prebending treatment, i.e. repeated bending loads at room temperature. In case of CuNb/Nb3Sn wires, for instance, Jc at 19 T becomes twice than that without prebending treatment (Figure) and Bc2 at 4.5 K increases from 23.7 T to 25.2 T (inset). In addition, Tc becomes 17.9 K from 17.4 K by the prebending treatment. It is considered that those enhancements are explained by the reduction of not only the axial residual strain but also radial/tangential one.

IMR, Tohoku University: S. Awaji, H. Oguro, G. Nishijima, K. Watanabe
Reference: S. Awaji, H. Oguro, G. Nishijima and K. Watanabe, "Enhancement of upper critical field and critical temperature by prebending process for practical Nb3Sn wires", Jpn. J. Appl. Phys., 43 (2004) L709-L711.

室温における繰り返し曲げ歪処理である事前曲げ歪処理を施すことによって,臨界電流密度,上部臨界磁場,臨界温度の大幅な向上がみられることを発見した.例えばブロンズ法CuNb/Nb3Sn線材の場合で,19 TにおけるJcが約2倍となり(図),Bc2は23.7 Tから25.2 Tまで向上する(挿入図).さらにTcも17.4 Kから17.9 Kへ上昇する事が分かった.これらの特性向上は,軸方向だけでなく径/接線方向の残留ひずみの緩和に起因していると考えられる.

東北大学 金属材料研究所:淡路 智,小黒英俊,西島 元,渡辺和雄