与Nb3Sn相比，Nb3Al具有非常高的超导转变温度、上临界场和临界电流密度，以及优良的应力-应变容许特性，因此在高场超导磁体应用上有着巨大潜力。由于成相条件苛刻，目前高性能Nb3Al超导体须通过2000℃快热快冷得到晶粒细小的非平衡Nb(Al)ss过饱和固溶体，以及低温退火获得。本项目提出利用机械合金化制备Nb-Al非平衡相，结合粉末装管法和低温热处理制备Nb3Al线材路线。通过前期研究，我们成功制备了首根机械合金化Nb3Al超导线材，但由于缺乏对Nb3Al相形成过程研究，制备的超导体性能仍然较低。因此，本项目拟利用高分辨透射电镜和原位中子衍射等手段，开展机械合金化过程中Nb-Al非平衡相微观结构演变规律以及Nb3Al超导相析出机理的研究；并通过合金元素添加调节Nb3Al相的析出，以及超导体的晶粒连接和磁通钉扎机制；解决机械合金化手段制备高性能Nb3Al超导材料过程中的关键基础科学问题。

Due to with excellent Tc, Hc2 and Jc properties as well as good strain-stress tolerance, Nb3Al superconductor is thought as a very promising candidate at the high-field superconducting magnets application. However, because of its phase formation conditions limit, Nb3Al superconductor with good performance must be prepared by the rapid heating and quenching approach up to 2000 ℃ for obtaining metastable Nb(Al)ss supersaturated solid solution with fine grains, and then Nb3Al phase precipitates after a low-temperature heat-treatment. In this project, it was proposed to develop high-performance Nb3Al wires by using mechanical alloying method to make metastable Nb-Al nonequilibrium phase and with the powder-in tube and low-temperature annealing process. By our previous efforts, the first mechanical-alloyed Nb3Al superconducting wire was successfully fabricated; but since the formation mechnism of Nb3Al phase kept unknown,its superconducting propeties was still low. Therefore, this project aims to clarify the microstructure evolution process of metastable Nb-Al nonequilibrium phase and the precipitation mechanism of Nb3Al superconducting phase by high-resolution transmission electron microscope and in-situ neutron diffraction method,and also researches the role of the added alloying-elements in adjusting the precipitation mechanism of Nb3Al phase and grains-connectivity and flux pinning of Nb3Al superconductor. This work will offer the possibility to solve the key fundamental scientific problems, which are confining the mechanical alloying way to develop the high-performance Nb3Al superconducting wires.