添加B对LaFe11.5Si1.5快淬带残余α-Fe相以及磁热效应的影响

Influences of Boron Addition on Residual α-Fe Phase and Magnetocaloric Effect of LaFe11.5Si1.5 Melt-Spun Ribbons

摘要:

通过微观分析研究添加B对LaFe11.5Si1.5快淬带中α-Fe杂相的影响，并探讨LaFe11.5Si1.5Bx (x=0.5，0.7，1.0)化合物的磁相变和磁热效应。与LaFe11.5Si1.5比较， 加入B后快淬薄带的显微组织显著细化, 在较高B含量的快淬薄带中还得到了非晶态结构。经1000 ℃回火2~10 h后，快淬试样均结晶为立方NaZn13型的La(Fe,Si)13化合物结构。含B快淬薄带经过较短时间的热处理就能得到单相结构，而且残留的α-Fe含量显著降低。磁性能测试表明，随着B含量的增大，LaFe11.5Si1.5Bx (x=0.5,0.7,1.0)化合物的居里温度略有升高；当B含量较低时，化合物具有一级磁相变特征并表现出与LaFe11.5Si1.5化合物相同的巨大磁热效应。

Abstract:

The influences of boron addition on secondary phase α-Fe in LaFe11.5Si1.5 melt-spun ribbons were investigated by SEM, TEM and XRD. The magnetic transition and magnetocaloric effect of LaFe11.5Si1.5Bx compound (x = 0.5, 0.7, and 1.0) were discussed. Compared with LaFe11.5Si1.5, the melt-spun ribbons have much finer microstructure after B addition, and even amorphous structure is obtained when B content is higher. The melt-spun specimens were crystallized into La(Fe,Si)13 compound structure of cubic NaZn13-type after annealing at 1000 °C for 2-10 h. The annealing time can be reduced after B atom introduction to get single phase structure and the amount of residual α-Fe is decreased significantly. Magnetic property test show that Curie temperature of the LaFe11.5Si1.5Bx compound (x = 0.5, 0.7, and 1.0) increased slightly with B content increasing; the LaFe11.5Si1.5B0.5, i.e. low-B-content compound, exhibited first-order magnetic transition characteristics and had the same giant magnetocaloric effect with LaFe11.5Si1.5.