Phase Formation and Superconductivity of Nb3Al Bulk Materials Prepared by Spark Plasma Sintering and Powder Metallurgy

Although various methods have been used to prepare Nb3Al superconducting materials to accelerate their commercialization, the preparation of Nb3Al by spark plasma sintering (SPS) is rarely reported. In this paper, Nb3Al superconductors were successfully prepared by SPS technology. By comparing with the traditional powder metallurgy (PM) method, the phase formation mechanism and superconducting properties of SPS-Nb3Al were investigated. The results show that the SPS-Nb3Al has a larger lattice constant similar to the high-temperature melt phase, and its lattice constant is very sensitive to the annealing treatment. It reveals that in SPS process, the local high temperature generated by plasma heating accelerates the formation of Nb3Al phase. In addition, the short reaction time and fast cooling make the Nb3Al grains small and tightly connected. The Al content in SPS-Nb3Al is relatively high, which results in a better superconductivity compared with the PM-Nb3Al.