芯丝中Ta分布对NbTiTa超导线材性能的影响

Effect of Ta Distribution in Filament on Property of NbTiTa Superconductor

用Nb47Ti片和Ta片制备NbTiTa/Cu超导线材,在三次热挤压和热处理后NbTiTa超导线材的芯丝中Ta成豆状和条带状,Ta和Nb47Ti间的互扩散很小。在NbTiTa超导芯丝中α-Ti钉扎中心成条带状,厚度为5～10nm,间距为20～50nm,讨论了α-Ti钉扎中心的尺寸和间距对磁通钉扎效果的影响。结果表明,当温度降到3.0K时NbTiTa/Cu超导线材在高场中的临界电流密度反映出Ta在芯丝中作为非超导相依然能够起到提高线材的上临界场和高场中临界电流密度的作用。不同直径的NbTiTa/Cu超导线材的临界电流密度表明,较大的最终附加应变对临界电流密度的提高具有重要意义,如果进一步减小线材的直径,线材的临界电流密度可以继续提高。

NbTiTa/Cu superconducting wires were fabricated with Nb47Ti sheets and Ta sheets,Ta sheets become the shape of bin and ribbon after three times extrusion,and the mutual diffusion between Ta sheets and Nb47Ti sheets is weak.The size and space of α-Ti pinning center in filaments is 5～10 nm and 20～50 nm,respectively.And the effects of size and space of α-Ti pinning center on flux pining were discussed.The critical current density at 3.0 K shows that Ta as non-superconductive phase can still increase the upper critical field and the critical current density of the wire in high field.The critical current density of wires with different diameter reveals that final strain heavily affects the critical current density,which can be increased furtherif the diameterof wire is decreased on and on.