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采用套管法,结合挤压、拉拔和轧制等塑性加工过程制备了Nb3Al超导线材前驱体长线,并利用自主设计制作的急热急冷(~2000℃,RHQ)装置对线材样品进行RHQ热处理和低温成相退火,获得了高性能的Nb3Al超导线材.结果表明,该线材由管状Nb3Al超导体、Nb基体骨架和孔洞组成;即通过RHQ热处理使Al芯与周围的Nb实现固溶体化,并留下孔洞,随后的低温成相退火使Nb-Al固溶体生成了管状Nb3Al超导体,而在距离Al源较远的位置则留下未反应的Nb基体骨架.通过扫描电子显微镜和磁化率测量显示,该线材中Nb3Al超导体具有精细的晶粒尺寸(50~100 nm)和良好的晶粒连接性;不同样品的起始超导转变温度(Tc)均达到了约17 K,表明该线材中Nb3Al超导体的Nb/Al原子比接近理想的3:1.因此,利用套管法有望制备出满足下一代高场磁体应用的高性能Nb3Al超导线材.
The precursor of Nb3Al superconducting wire rod was prepared by the casing method combined with extrusion, drawing and rolling process. The wire rod sample was RHQ (~ 2000 ℃, RHQ) The results show that the wire consists of a tubular Nb3Al superconductor, a Nb matrix skeleton and pores; that is, the Al core and the surrounding Nb are solid-solutionized by RHQ heat treatment, and Leaving the hole, followed by annealing at low temperature into the Nb-Al solid solution to form a tubular Nb3Al superconductor, while away from the Al source left unreacted Nb matrix skeleton by scanning electron microscopy and magnetic susceptibility measurements show that, The Nb3Al superconductor in the wire has fine grain size (50-100 nm) and good grain connectivity. The initial superconducting transition temperature (Tc) of all the samples reached about 17 K, indicating that the Nb3Al superconductor Nb / Al atomic ratio close to the ideal 3: 1. Therefore, the use of casing method is expected to be prepared to meet the next generation of high-field magnet applications of high-performance Nb3Al superconducting wire.