冷却速率对(Bi,Pb)-2223/Ag超导带材微观结构和性能的影响

Effects of the Cooling Rate on the Microstructure and Properties of (Bi,Pb)-2223/Ag Tapes

研究了(Bi,Pb)-2223/Ag带材在第1次热处理后,不同的冷却速率对其输运性能和微观结构的影响。利用XRD、SEM等分析手段对样品进行表征。结果表明:随着冷却速率的降低,带材中的2201相不断减少直至消失,而Ca2PbO4相的含量却不断增加;与此同时,带材中第二相粒子的尺寸也不断增大。带材的输运电流测量表明,随冷却速率(对数坐标)的降低,样品的临界电流密度线性增加,同时,带材在磁场下的性能也不断提高。这是由于慢冷导致(Bi,Pb)-2223/Ag带材的晶粒连接性变好和磁通钉扎能力提高造成的。

The influence of cooling rates on the microstructure and transport properties of （Bi,Pb）-2223/Ag tapes after the first heat treatment was investigated. The samples were characterized by XRD and SEM. Results show that the 2201 phases decrease until disappear while Ca2PbO4 increases continuously as the cooling rate decreases; at the same time the size of non-superconducting secondary phase particles become larger. The transport current tests show that the critical current density increases linearly with the cooling rate decreasing logarithmically; meanwhile, the transport current properties of the tapes in the magnetic field increases. This behavior is attributed to improvement of the grain connectivity and flux pinning properties of the tapes as the cooling rate is decreased.