MgB2超导线材具有巨大的应用潜力和良好的应用前景。目前，MgB2超导线材的性能仍存在很大的提升空间，限制其性能进一步提高的主要问题是在常压合成条件下MgB2中生成大量孔洞，导致有效载流面积和作为有效钉扎中心的晶界密度减小。本项目通过分步反应法制备MgB2超导线材，采用MgB4作为B源，降低B源的反应活性以改变Mg-B间扩散反应行为和过程，探索常压条件下制备高致密度MgB2超导线材的新合成方法；探索分步反应中元素掺杂对Mg-B扩散反应的影响，建立MgB2超导体中孔洞的生成模型，揭示影响生成高致密度MgB2线材的主要因素，阐明分步反应法制备高致密度MgB2的反应机制，达到对MgB2超导线材的密度调控。并在此基础上研究掺杂对分步反应法制备的MgB2超导线材性能的影响规律。相关研究对于进一步提高MgB2超导线材的性能，推动其实现实用化具有重要意义。

MgB2 superconducting wires have large potential applications and good application prospects. The superconducting properties of MgB2 wires still have great scope for further improvement in the coming years. The main problem is the formation of many pores during the synthesis of MgB2 at ambient pressure, which limites the further improvement of superconducting properties of MgB2 wires. The pores reduce the effective current area and the boundary density as effective pinning centers. This project aims to study the preparation of MgB2 superconducting wires by stepwise synthesis. We use MgB4 as the resource of B to reduce the reaction activity of B and change the process of Mg-B diffusion reaction, and explore the new synthesis method of preparing high density MgB2 superconducting wires. The effect of element doping on the diffusion reaction is explored. The forming model of pores in MgB2 superconductor is established. The main factors on preparation of high density MgB2 superconducting wires will be revealed. It is elucidated that the reaction mechanism in order to tune the density of superconducting MgB2 wires. And based on above conclusions, the influence law of element doping on superconducting properties of MgB2 wires prepared by stepwise synthesis methode will be investigated. The results will lay the fundations on practical applications and further improve the superconducting properties of MgB2 superconducting wires.