原位法低温合成MgB2的孔隙形成机制

The Mechanism of Pore Formation in Superconducting MgB2 Synthesized at Low Temperature by In-Situ Process

摘要:

采用XRD、SEM、DSC等分析测试方法，研究原位法低温合成MgB2的孔隙形成机制。结果表明，高能球磨后B小颗粒镶嵌在Mg大颗粒上，热处理时MgB2相首先在Mg、B的镶嵌区域生成。MgB2相生成过程中，闭孔隙主要是由Kirkendall效应造成的，开孔隙形成的主要原因是Mg气化后与B反应形成了与环境保持连通的孔隙。

Abstract:

Using X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) the mechanism of pore formation of superconducting MgB2 synthesized at low temperature by in-situ process was studied. It is showed that B powder was embedded into Mg powder after the ball-milling process. MgB2 phase formed firstly in these embedded areas. The closed pores in MgB2 bulks are caused by kirkendall effect due to the different diffusion speeds of Mg and B atoms. The open pores are caused by Mg gas.