Infiltration behavior of molten Mg and its influence on microstructural evolution in SiC-doped MgB2 wires prepared by internal Mg diffusion
Infiltration behavior of molten Mg and its influence on microstructural evolution in SiC-doped MgB2 wires prepared by internal Mg diffusion
复制标题
内镁扩散法制备的 SiC 掺杂 MgB2 丝中熔融镁的渗透行为及其对微观结构演变的影响
DOI：
10.1016/j.jallcom.2018.01.012
复制
发表时间：
2018
影响因子：
6.2
通讯作者：
Hiroaki Kumakura
中科院分区：
文献类型：
--
作者：
Yusuke Shimada;Satoshi Hata;Ken-ichi Ikeda;Hideharu Nakashima;Akiyoshi Matsumoto;Kazumasa Togano;Hiroaki Kumakura
通过多尺度微观结构观察，阐明了用内扩散法(IMD)在两种不同温度下制备的镁B2线的微结构演变。IMD方法提高了镁B2丝的临界电流，但其临界电流不足以满足实际应用的需要。用IMD法制备硼化镁时，需要熔融的镁渗入B颗粒之间的缝隙，并穿透每个B颗粒。在这里，我们认为控制镁的渗透和渗透行为是提高IMD法制备的镁的IcB_2的关键。Ic值降低的原因之一是在MgB2晶区存在残留的B颗粒，即使在表现出最高Ic的MgB2丝中也有25%的面积分数。高温处理后，由于镁原子在B颗粒中穿透距离不足而形成的残留B颗粒数量减少。然而，在高于镁熔点的温度下，由于镁迅速而不均匀地渗入B晶间的间隙，制备的镁B2丝的组织不均匀。因此，优化热处理温度可以有效地控制镁在B晶中的渗入和渗透，获得均匀的显微组织。
We elucidate the microstructural evolution in MgB2wires fabricated at two different temperatures by the internal Mg diffusion (IMD) method via multiple-scale microstructural observations. The critical current (Ic) of MgB2wire was enhanced by the IMD method; however, theIcof MgB2was not sufficiently high to allow its practical applications. To prepare MgB2by the IMD method, molten Mg is required to infiltrate the gaps between the B grains and penetrate each B grain. Here, we suggest that controlling the infiltration and penetration behaviors of Mg are key to enhancing theIcof MgB2fabricated by the IMD method. One reason for the decrease inIcis the existence of residual B grains in the MgB2crystalline region, which has an area fraction of 25% even in the MgB2wire exhibiting the highestIc. The amount of residual B grains, which formed due to the insufficient penetration distance of Mg atoms in the B grain, decreased after high-temperature treatment. However, the microstructure of the MgB2wire fabricated at a temperature higher than the melting point of Mg was non-uniform because Mg infiltrated the gap between the B grains rapidly and non-uniformly. Thus, optimization of heat treatment temperature can effectively control the infiltration and penetration of Mg in the B grains, yielding uniform microstructures.