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用自蔓延高温合成法(SHS)制备了MgCNi_3超导块材,用XRD和SEM对试样进行了表征,理论计算和实验结果表明,如果预热温度太低,自蔓延过程不能进行,当预热温度大于620℃时才能用电弧引燃反应,预热速率越小试样越致密;Mg粒度越小反应后绝热温度越高,成相速率越快,并导致合成产物出现烧结现象,样品所形成的致密度和孔洞尺寸依赖于原始Mg粉的粒度,Mg粒度越小,试样越致密,孔洞越小,但是Mg粒度不同不改变晶粒的形成和生长机理.
The MgCNi 3 superconducting blocks were prepared by SHS method. The samples were characterized by XRD and SEM. The theoretical calculation and experimental results show that the self-propagating process can not be performed if the preheating temperature is too low. When the hot temperature is higher than 620 ℃, the arc can ignite the reaction. The smaller the preheating rate is, the smaller the Mg particle size is. The higher the adiabatic temperature is, the faster the phase velocity is, and the sintering phenomenon of the synthesized product occurs. The formed density and pore size depend on the particle size of the original Mg powder. The smaller the Mg particle size is, the denser the sample and the smaller the pores. However, the different Mg particle size does not change the formation and growth mechanism of the Mg particles.