Application of thermal analysis technology to diffusion heat treatment processing of Nb₃Sn multifilamentary superconductors

Thermal analysis technologies, including differential scanning calorimetry (DSC) and thermal gravity analysis (TG) ,were used to studying the heat treatment diffusion processing of Nb₃Sn multifilament superconductors. The Nb₃Sn wires were heat treated in vacuum according to the thermal analysis results. The microstructure evolution of Nb₃Sn superconductors was analyzed using X-ray diffraction and scanning electron microscopy. The results show that the heat treatment temperature range can be obtained through thermal analysis technology. The fine grain structured Nb₃Sn multifilament superconductors were fabricated successfully during the heat treatment at 670 t. The critical current test results confirmed that heat treated conductors possess superconductivity under liquid helium temperature condition.