较之高温制备,低温活化烧结技术可有效避免MgB_2超导块体制备中的一些问题,如Mg易挥发、高温MgB_2晶粒长大、结晶度高等问题.为进一步提高超导块体的载流能力,J Shimoyama等采用金属Ag掺杂并在550℃烧结72h后获得了高性能的MgB_2超导体,使得金属Ag成为低温活化烧结的有效组元.然而,对金属Ag低温活化烧结MgB_2超导块体的成相机理尚缺乏系统的分析和理解.本文系统研究了金属Ag掺杂MgB_2超导块体的成相动力学过程,发展了金属Ag掺杂低温活化快速制备技术,结合液相活化烧结理论阐述了金属Ag掺杂MgB_2块体的低温活化烧结机理.
Comparing with high-temperature sintering, low-temperature sintering could avoid some problems in fabrication of MgB_2 superconductor, such as volatility of Mg, growth of MgB_2 grain, high crystallinity etc. In order to improve the critical current density of MgB_2 superconductor, Shimoyama et al. obtained high performance MgB_2 by sintering at 550℃ for 72h, which indicated that Ag could activate the sintering process. However, the sintering mechanism of MgB_2 with Ag addition is still unknown. In the present paper, we have investigated this mechanism according to liquid activated mechanism and provide the selection rules of these metals which could activate the sintering process of MgB_2 at low temperature.
参考文献
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