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采用Nb/Cu复合管作为外包套材料,通过原位法粉末装管工艺(PIT)制备了C掺杂MgB2/Nb/Cu线材.在高纯流动氩气保护条件下、650～950℃温度区间内烧结2h.微观结构分析显示,通过该工艺制备的MgB2/NbZr/Cu线材具有良好的晶粒连结性和较高的致密度.X射线衍射(XRD)分析表明在750℃左右可以生成纯度较高的MgB2相,在低温和高温下烧结后均有杂相峰出现,并且高温烧结后所生成的相结构较为复杂.采用四引线法超导临界电流的测试结果表明,低温烧结后的线材具有超导电流传输性能,而当热处理温度超过750℃时,样品中的电流传输状态表现为正常电阻态.实验结果证实采用Nb作为原位法MgB2超导线材的包套阻隔层时,成相热处理一般应该在低于750℃的温度下进行.
C / MgB2 / Nb / Cu wires were prepared by in-situ powder tube packing (PIT) method using Nb / Cu composite tube as sheath material.Under high purity flowing argon gas protection condition, the temperature range of 650-950 ℃ Sintering within 2h.Microstructure analysis showed that the MgB2 / NbZr / Cu wire prepared by this process has good crystallinity and high density.The X-ray diffraction (XRD) analysis shows that the purity can be higher than 750 ℃ High MgB2 phase, heterogeneous peaks appeared after sintering at low temperature and high temperature, and the phase structure formed after high temperature sintering was more complicated.The test results of superconductivity critical current by four-lead method showed that the low temperature sintered wire had Superconducting current transfer performance, and when the heat treatment temperature exceeds 750 ℃, the current state of the sample showed normal resistance state.Experimental results confirm the use of Nb as the in-situ MgB2 superconducting wire cladding barrier, the phase heat treatment It should generally be carried out at temperatures below 750 ° C.