Nb_3Sn超导相的微观组织表征与Sn扩散的研究

Study on microstructural characterization and Sn diffusion of Nb_3Sn superconducting wire

CICC导体作为45T混合磁体外超导磁体的重要绕制材料,其所用的超导股线是由牛津公司提供的RRP法制备的高临界电流Nb_3Sn超导线材。由于Nb_3Sn超导相为典型的A15结构,其塑性非常差,所以在实际工程应用当中,往往是采用先绕制线圈,然后对绕制好的线圈进行热处理,进而生成Nb_3Sn超导相。因此,热处理制度的合理制定对于Nb_3Sn超导相的微观组织结构和超导性能具有非常重要的意义。为了验证热处理故障对超导磁体性能的影响,研究制定了三种不同的热处理制度,利用SEM方法对其生成的Nb_3Sn超导相进行微观组织的表征,通过EDS分析Sn元素的扩散;结合Ic值和RRR值的测定结果,对比分析不同热处理制度对Nb_3Sn股线微观组织与性能的影响。

As an important wound material for superconducting magnet coils of 45T hybrid magnet, CICC＇ s superconducting strands are made of high critical current Nb3Sn superconducting wire which is manufactured by Oxford company by means of RRP. Since Nb3Sn superconducting phase is atypieal A15 structure, whose plasticity is very poor, and thereby in the engineering application, the coils shall be often wound first, and then heat treatment be carried out on the wound coils, so as to generate Nb3 Sn superconducting phase. Therefore, it is of great significance for the mierostructure and properties of Nb3 Sn superconducting phase to establish reasonable heat treating regime. For the purpose of verifying the effect of heat treatment on the performanee of superconducting magnet, this paper developed three different heat treatment systems. The microstrueture of Nb3 Sn superconducting phase was visualized by means of SEM on samples, and the EDS of Nb3Sn was carried out to analyse its diffusion of the Sn element. Also, according to the results from the value of critical current Ic and RRR, this paper analyzed the influence on mi- erostrueture and properties of Nb3 Sn strands in different heat treatment systems by contrast.