Strain dependence of the critical current of Nb3Sn superconductors doped with Hf and Ga

✍ Scribed by H. Sekine; K. Inoue; T. Kuroda; K. Tachikawa

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 456 KB
• Volume: 29
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(89)90034-9

✦ Synopsis

Strain dependence of/~ of bronze-processed Nb-Hf/Cu-Sn-Ga superconductors (namely Nb3Sn superconductors fabricated with starting composite consisting of a Nb-Hf alloy core and a Cu-Sn-Ga sheath) and that of Cu-Sn-Ga/Nb-Hf superconductors (Nb3Sn superconductors fabricated with starting composite consisting of a Cu-Sn-Ga alloy core and a Nb-Hf alloy sheath) were studied. It has been revealed that the additions of Hf and Ga improve strain tolerance of I c for both kinds of Nb3Sn superconductors. / c of Nb3Sn superconductors to which Hf and Ga are added scarcely depends on strain at 6.5 T in contrast ~to Ic of pure Nb3Sn superconductors, sirr (the value of strain up to which the reversibility of the / c -strain curve is preserved) decreases with increasing thickness of the Nb3Sn layer. The existence of the negative and positive residual strains in the Nb-(Hf)/Cu-Sn-(Ga) and Cu-Sn-(Ga)/Nb-(Hf) specimens, respectively, is considered to be the reason for the difference of / c -s (strain) curves of these specimens. Only fine cracks which distribute homogeneously throughout the Nb3Sn layer were observed in the specimen to which ~i,,-A~ had been applied. These fine cracks are considered to enable the reversible elongation and compression of the Nb3Sn layer up to ~,,~ 1%