Improved critical current in MgB_2 tapes sheathed with carbon steels
Improved critical current in MgB_2 tapes sheathed with carbon steels
复制标题
提高了碳钢护套 MgB_2 带的临界电流
DOI：
10.1557/jmr.2002.0343
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发表时间：
2002
影响因子：
2.7
通讯作者：
K. Togano
中科院分区：
文献类型：
--
作者：
H. Fujii;H. Kumakura;K. Togano
采用管内粉末法制备了以铁和碳钢为护套材料的MgB_2带。在轧制状态下，cs -护套带的输运临界电流密度（j_c）高于fe -护套带。这是由于高密度的MgB_2层与CS的高机械强度相关。此外，800°C以上的热处理对提高这些带的j_c非常有效。经过热处理的cs -护套带在4.2 K和7.5 T下的J - c值为10 kA/cm^2，在10 T下仍高于2 kA/cm^2，这是MgB_2带的最高J - c值。在J _c-B数据中，外推到0 T约为1 MA/cm^2，这与鞘层材料无关。显微组织观察表明，CS包覆带的高j_c和j_c性能的小场依赖性可归因于CS的高机械强度改善了晶粒连连性和晶粒取向。
We fabricated MgB_2 tapes by a powder-in-tube method using sheath materials of Fe and carbon steel (CS). In the as-rolled state, the CS-sheathed tapes showed higher transport critical current density ( J _c) values than the Fe-sheathed tape did. This is due to the higher-density MgB_2 layer associated with the high mechanical strength of the CS. Furthermore, heat treatment above 800 °C was very effective in increasing the J _c of these tapes. The heat-treated CS-sheathed tapes showed J _c values of 10 kA/cm^2 at 4.2 K and 7.5 T and still above 2 kA/cm^2 at 10 T. These values are the highest ever reported for MgB_2 tapes. An extrapolation to 0 T in the J _c-B data gave about 1 MA/cm^2, which was independent of the sheath materials. Microstructural observations suggest that the high J _c and the small field dependence of the J _c properties of the CS-sheathed tapes can be ascribed to the improved grain connectivity and grain alignment produced by the high mechanical strength of CS.