MgB2超导线圈的交流损耗仿真和实验研究

本文采用MgB2/Fe/Cu单芯复合线材制作了一个小型实验线圈,并以此为基础,对用MgB2线、带材制成的线圈在承载较大电流情况下的交流损耗特性进行了仿真和实验研究,结果表明,为使MgB2/Fe/Cu复合线材适于电力应用,应设法大幅降低基体损耗.     

Enhancement of Critical Current Density in Graphite Doped MgB2 Wires

Graphite doped MgB2-xCx (x = 0.00, 0.05, 0.10) wires were fabricated via the in situ powder-in-tube method in flowing argon by using low carbon steel tubes as the sheath materials. With the increase of graphite concentration,the amount of unreacted graphite in the core area increases, and the average grain size of MgB2 decreases. It is found that the critical current density Jc can be significantly improved by graphite doping. The MgB2 wire with x = 0.05 exhibits the best Jc value of 16710 A/cm^2 at 6K, 4.5T, but the MgB1.9C0.1 wire has the highest Jc value of 2060 A/cm^2 at 6 K, 8 T. It is suggested that the enhancement of Jc is due to not only the improvement of the microstructure features but also the introduction of pinning centres.     

热处理和添加元素对MgB2晶畴尺寸和微观应变的影响

用X射线衍射仪和扫描电镜研究了热处理温度和添加元素(Ti, Zr)对单相MgB2粉末样品的晶畴尺寸和微观应变的影响.结果表明,无论是没添加的还是添加了合金元素的MgB2样品,随热处理温度的升高晶畴尺寸明显增大.在同样处理制度下,添加元素样品的晶畴尺寸明显小于不添加的样品.随热处理温度的升高,微观应变有降低的趋势.晶畴尺寸的测试结果与扫描电镜的观测结果表现出很好的一致性.实验说明,添加元素(Ti, Zr)MgB2样品临界电流密度的提高,与晶格畸变增加,晶畴尺寸变小,晶界增多,导致钉扎力增加有关.