High-performance dense MgB2 superconducting wire fabricated from mechanically milled powder
High-performance dense MgB2 superconducting wire fabricated from mechanically milled powder
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DOI：
10.1088/1361-6668/aa5f36
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发表时间：
2017-04-01
影响因子：
3.6
通讯作者：
Kishio, Kohji
中科院分区：
文献类型：
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作者：
Kodama, Motomune;Suzuki, Takaaki;Kishio, Kohji
由于相对较高的临界温度和较低的制造成本，MgB2超导线材在无液氦超导应用中具有广阔的前景。如今，商用 MgB2 线是通过原位或异位粉末管内工艺制造的，原位工艺更有效地获得高临界电流密度。然而，在原位处理的线材中，MgB2 丝的高孔隙率严重抑制了临界电流密度。为了解决这个问题，我们提出了一种创新方法，使用通过机械研磨镁、硼和晕苯粉末制备的前体粉末。该前体粉末具有金属基体复合结构，其中硼颗粒分散在镁基体中。前驱体粉末通过线材加工产生塑性变形，致密堆积，热处理后生成致密的MgB2丝。克服了典型原位过程中临界电流密度的限制，在10 K和6.1 T、15 K和4.8 T、20 K和3.3 T下获得了10(3)Amm(-2)的实用临界电流密度。
Owing to the relatively high critical temperature and the low manufacturing cost, MgB2 superconducting wires are promising for liquid helium-free superconducting applications. Today, commercially available MgB2 wires are manufactured by either an in situ or ex situ powder-in-tube process, the in situ process being more effective to obtain high critical current density. In in situ-processed wires, however, the critical current density is seriously suppressed by the high porosity of MgB2 filaments. To resolve this problem, we propose an innovative method of using precursor powder prepared by mechanical milling of magnesium, boron, and coronene powders. This precursor powder has a metal-matrix-composite structure, in which boron particles are dispersed in a magnesium matrix. The plastic deformation of the precursor powder through wire processing leads to compact packing, and a dense MgB2 filament is generated after heat treatment. As a result, the limitation of critical current density that occurs for the typical in situ process is overcome, and the practical critical current density of 10(3)Amm(-2) is obtained at 10 K and 6.1 T, at 15 K and 4.8 T, and at 20 K and 3.3 T.