Yao W J, Zhang Y Y, Wang N, Lee J H
J Nanosci Nanotechnol. 2015 Mar;15(3):2579-85. doi: 10.1166/jnn.2015.10250.
The (Fe,Co)-(Fe,Co)17Gd2 pseudo-binary eutectic system has been determined by investigating phase compositions on the analysis of DSC, EDS and XRD. The rapid solidification of Gd7.3Fe30.56Co62.14, Gd9Fe30Co61 and Gd9.63Fe29.79Co60.58 ternary alloys is realized by single roller techniques. With a rising cooling rate, the equiaxed zone near the roller surface expands inwards. For Gd7.3Fe30.56Co62.14 hypoeutectic alloy ribbons, the feathery irregular eutectic zone shrinks and the grains (Fe,Co) near the free surface are refined. (Fe,Co) equiaxed dendrites plus the radial, irregular eutectic ultimately fill in the ribbon at the maximum cooling rate. For Gd9Fe30Co61 near-eutectic alloy ribbons, the growth direction of irregular eutectics near the free surface becomes more and more perpendicular to the surface, and finally the whole ribbons are occupied by the fine, irregular eutectic. The dendritic spacing of the (Fe,Co)17Gd2 phase which grows from the roller surface to the free surface in Gd9.63Fe29.79Co60.58 alloy ribbons becomes smaller. The grain size of the (Fe,Co)17Gd2 dendrite and the fraction of (Fe,Co) soft phase in alloy ribbons, which determine coercivity in the pseudo-binary eutectic system, vary with the increase of the cooling rate. Of the three alloys, the Gd9Fe30Co61 alloy has the best hard magnetic properties at Vr = 20 m/s; the maximum coercivity Hc is 431.34 Oe.
通过对差示扫描量热法（DSC）、能谱仪（EDS）和X射线衍射仪（XRD）分析所得的相组成进行研究，确定了(Fe,Co)-(Fe,Co)17Gd2伪二元共晶体系。采用单辊技术实现了Gd7.3Fe30.56Co62.14、Gd9Fe30Co61和Gd9.63Fe29.79Co60.58三元合金的快速凝固。随着冷却速率的提高，辊面附近的等轴区向内扩展。对于Gd7.3Fe30.56Co62.14亚共晶合金薄带，羽毛状不规则共晶区收缩，自由表面附近的(Fe,Co)晶粒细化。(Fe,Co)等轴枝晶加上径向不规则共晶最终在最大冷却速率下填满薄带。对于Gd9Fe30Co61近共晶合金薄带，自由表面附近不规则共晶的生长方向越来越垂直于表面，最终整个薄带被细小的不规则共晶占据。在Gd9.63Fe29.79Co60.58合金薄带中，从辊面生长到自由表面的(Fe,Co)17Gd2相的枝晶间距变小。决定伪二元共晶体系矫顽力的(Fe,Co)17Gd2枝晶的晶粒尺寸和合金薄带中(Fe,Co)软相的比例随冷却速率的增加而变化。在这三种合金中，Gd9Fe30Co61合金在Vr = 20 m/s时具有最佳的硬磁性能；最大矫顽力Hc为431.34奥斯特（Oe）。
