Elsevier

Physica B: Condensed Matter

Volume 476, 1 November 2015, Pages 150-153
Physica B: Condensed Matter

Effects of the ingot phase transition on microstructure and magnetic properties of CeNdFeB melt-spun ribbons

https://doi.org/10.1016/j.physb.2015.03.005Get rights and content

Abstract

The paper studies the phase transition of ingot with the composition (Ce50Nd50)30FebalCo4Ga0.2B0.92 after the annealing treatment at 1050 °C. The melt-spun ribbons which is prepared by the two treatment status ingots. The phase structure and microstructure morphologies of the ingots and melt-spun ribbons were analysed and observed by XRD and SEM. It was found that the grain size of the ribbons is on the nanometer scale. The EDS results show that there are four different phases in the ingot: (CeNd)2Fe14B, α-Fe, Ce-rich phase and Nd-rich phase. After the annealing treatment, α-Fe, Ce-rich phase, and Nd-rich phase were obviously reduced and the contents of the main phase was significantly increased in the annealed ingot compared with the unanneal treatment ingot. The VSM results show that there is a peak waist in the ribbon which is prepared by the untreated ingot. Because the ingot is uneven, the ribbons may have the secondary phase, the Hcj is 8394 Oe. But the demagnetization curves of the ribbons, which is prepared by the annealed ingot, is relatively smooth and without the soft magnetic phase and the Hcj is 12,528 Oe, which is higher than the unanneal treatment ingot. We can know that the ingot with fine organization is the key factors to preparing high-performance ribbons.

Introduction

Since the outstanding magnetic properties of Nd–Fe–B was found in 1983, it has been studied in many ways [1]. The usage of neodymium with the production of rare earth permanent magnet has increased significantly in the world. Nd takes up more than 90% of the cost of NdFeB permanent magnet. So there is economic and scientific interest in attaining high permanent magnet properties while reducing using rare-earth elements. As in fact, there are abundant and inexpensive metals on the earth, such as La, Ce, although the magnetic moments and anisotropy field of La2Fe14BCe2Fe14B are much lower than those of Nd2Fe14B, which cannot be used alone to meet the users’ requirements. But the experimental results showed that the Ce can partly replace Nd in magnet, and the loss of performance is in an acceptable range [2], [3]. The magnet is made of the magnetic powder, which is from the alloy ingots. So the initial state of the ingot will have an effect on the melt-spun ribbons. In this paper, we study on the phase transition of ingot with the composition (Ce50Nd50)30FebalCo4Ga0.2B0.92 after the annealing treatment.

Section snippets

Experimental procedure

The ingots of nominal composition of [(Nd)50(Ce)50]30FebalCo4Ga0.4B0.92 (wt%) were produced from individual elements having 99.99% purity using a laboratory scale argon-arc melting furnace with water cooled copper hearth [4], [5]. Half of the ingot was annealed at temperatures of 1050 °C for 2 h and then slow cooled to room temperature. The accuracy of the annealing temperature was ±2 °C. Then both of the ingots, annealed or not, were broken into small pieces and washed with acetone to remove any

Results and discussion

In order to control the quality of the phase of the ingot and ribbons, the oxygen content of them were strictly controlled in the preparation process. Finally, we got the oxygen content of the ingot was below 1.73E–4 and that of the ribbons was not higher than 2.48E–4. The low oxygen content is a key technical problem of the high performance magnet preparation.

Fig. 1 shows the 1/4 of ingot model and the region the blue side is observed under the scanning electron microscope. From the fracture

Acknowledgement

This work was supported by the National Basic Research Program of China (973 Program) (Grant no. 2014CB643701) and the National Natural Science Foundation of China, China (Grant no. 51171048).

References (8)

  • J.D. Wang et al.

    J. Rare Earths

    (2013)
  • I. Ahmad et al.

    J. Magn. Magn. Mater.

    (2012)
  • N. Watanabe et al.

    J. Alloys Compd.

    (2013)
  • H. Sepehri-Amin et al.

    Scr. Mater.

    (2013)
There are more references available in the full text version of this article.

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