Y-Co-M (M=Fe, Sn, and C) 複合奈米晶薄帶之硬磁特性與相變化研究

Hard magnetic properties and phase evolution of carbon doped Y(Co, M)5 (M= Fe, Sn) nanocomposite ribbons

歐葦辰(WEI-CHEN OU)

指導教授 ： 張文成

國立中正大學/理學院/物理學系/碩士(2016年)

摘要

本文主要探討Fe、C、Sn置換Co對1:5型Y-Co合金薄帶的磁性能以及相變化與微觀結構的影響。結果顯示以Fe元素對1:5型Y-Co合金進行置換可以提高合金薄帶的飽和磁化量。而若以C元素對1:5型Y-Co合金進行置換，除了有細化晶粒功能外還可以提高薄帶的矯頑磁力。而以Sn元素對1:5型Y-Co合金進行置換則發現大尺寸晶粒間會析出含Sn之小晶粒或晶界相，而合金的矯頑磁力也可些微提升，惟晶粒大小不均勻導致磁滯曲線之角行性並不佳。最後，再將Fe、C、Sn元素交叉同時置換Co以期得到磁性更優良的薄帶，結果發現YCo4.4Fe0.3C0.3磁石的薄帶有最佳的磁特性，其Br=6.4 kG、iHc>12 kOe，而 (BH)max可高達9.1 MGOe。經由顯微組織觀察及反應晶粒間作用力高低的Henkel 圖的研究結果顯示，晶粒細化造成磁性晶粒間之交換藕合效應大幅提升，是造成1:5型Y-Co合金薄帶殘留磁束密度及磁能積大幅提升的主要原因。

關鍵字

稀土永磁材料

並列摘要

This article explores the effect of Fe, C, Sn replacement for Co on the microstructure and magnetic properties of YCo5 alloy ribbons. Experimental results show that substituting few Fe for Co could improve the saturation magnetization of the YCo5 ribbons. Meanwhile, adding a slight carbon to YCo5 ribbons may refine the grain size and improve the coercivity effectively. In contrast, substituting few Sn for Co leads to the appearance of small Sn-rich grains or grain boundary phase. The coercivity may be slightly enhanced, however, the squareness of the demagnetization curve becomes inferior due to the inhomogeneous microstructure. At last, superior magnetic properties of the ribbons could be obtained if Fe, C are adopted in the alloy ribbons simultaneously. The optimal magnetic properties of Br=6.4 kG, iHc>12 kOe and (BH)max=9.1 MGOe are achieved in YCo4.4Fe0.3C0 ribbons. Based on the results of microstructural inveatigation and Henkel plot studies, extremely fine grains of the above 1:5 type alloy ribbons level up the exchange coupling effect between magnetic grains, yielding high remanence and high magnetic energy product eventually.

並列關鍵字

rare earth permanent magnet

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