| The superconducting magnetic confinement fusion is one of the sustainable energy technologies of human future. Now, it is of great significance to solve the energy crisis of future by International Thermonuclear Experimental Reactor (ITER) plan. Because the huge D-shapes coils should produce a peak magnet field of about 13 T, it is essential for the coil materials to have a good superconductivity and irradiation resistance in the high magnet field.At present, since the worse stress and strain resistance of early used Nb3Sn wires, researchers in the world are looking for an alternative superconducting magnet material with a better properties than the early Nb3Sn wire. One of potential materials is Nb3Al superconductor, which has the same A15 construction as Nb3Sn and a higher upper critical field Hc2, critical current density Jc and a better strain-stress resistance than Nb3Sn.The first chapter of this essay is mainly about the relevant knowledge of superconducting materials, including the definitions, characteristics, classifications and characterization parameters. Afterwards there has a brief explanation of the background and significance of Nb3Al. And then, this chapter also introduces the principle of diffusion method including diffusion mechanism and development about Nb3Al superconductor, and shows the major applications and some popular preparation methods as well as the research results of Nb3Al superconducting material at last.The second chapter mainly describes the Jelly-Roll method in detail, and also describes some relevant laboratory equipment and characterization instruments, including tube furnace, high-temperature heat treatment furnace, metallographic polishing machine, X-ray diffraction, scanning electron microscopy, and magnetic measurement systems.The third chapter explores the impacts on the Jelly-Roll Nb3Al wires through the low-temperature diffusion method. And research shows that, we can indeed obtain the superconducting Nb3Al wires at low temperature diffusion method, and especially in the sintering temperature range of 800℃ to 900℃. After the optimal experiments of sintering time, there is a big effect on the samples’ magnetic strength in the case of short time (3 hours to 15 hours) sintering, and this result indicates that there still does not have a relatively balanced state between the sintering temperature and the sintering time. But in the long time (20 hours to 30 hours) sintering, there just has a little influence on the magnetic properties through different sintering temperatures, so we can indicate that there has been have a relatively balanced state between the sintering temperature and sintering time. Eventually, through the analysis of samples’magnetic properties we can know that the optimal process parameter of low temperature diffusion method is sintering about 24 hours at 900℃, and the obtained Tc is about 15.1 K.The last chapter studies the influence of high temperature diffusion method process for the preparation of Nb3Al wires. When the temperature is higher than 1400℃, it is able to obtain a better performance than low-temperature diffusion treatment of these samples, and the higher the temperature, the higher the Tc. This paper mainly analysis the experiment results of the three temperature points about 1400℃,1450℃,1500℃. And in the case of 1400℃ sintering, the best sintering time is about 12 hours, and then the obtained Tc is about 15.8 K, as for the 1450℃ sintering, the best sintering time is about 3 hours, and then the obtained Tc is 16.5 K, when sintered at 1500℃, the best sintering time is 3 hours, and then the obtained Tc is about 16.8 K. |
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