Phase Formation, Microstructure, and Magnetic Properties of Nd_14.5Fe_79.3B_6.2 Melt-Spun Ribbons with Different Ce and Y Substitutions

Round 1

Reviewer 1 Report

The article:

„Phase formation, microstructure and magnetic properties of 2 Nd_14.5Fe_79.3B_6.2 melt-spun ribbons with different Ce and Y substitutions” by:  Q.J. Ke, F.L. Dai, S.X. Li, M.H. Rong, Q.R. Yao and J. Wang,

deals with interesting approach to experimental studies of phase formation and microstructure of (Nd_1-2xCe_xY_x)_14.5Fe_79.3B_6.2 (x=0.05, 0.10, 0.15, 0.20, 11 0.25) alloys. The authors in this work, investigated phase structure, microstructure and magnetic properties of alloys.

In order to obtain the appropriate results, the authors used for the research following methods:  X-ray diffraction, SEM micrographs, and Magnetic measurements. In conclusion the authors concluded that (Nd_1-2xCe_xYx)_14.5Fe_79.3B_6.2 annealed alloys contain  the (NdCeY)₂Fe₁₄B phase with the tetragonal Nd₂Fe₁₄B-typed structure (space group  P42/mnm), α-Fe phase and rich-RE (α-Nd) phase. Also the tendency of magnetic properties of the ribbons could result from the co-substitution of Ce and Y for Nd in Nd₂Fe₁₄B phase and different phase formation.

I have gone through the manuscript and I recommend it for publication in Materials with the following reasons:

The paper is scientifically sound and of important interest.

The information presented in the paper is original and comprehensive.

The results and discussion sections were well-written and thorough.

Although the article is very interesting but before publishing requires a following addition:

1. What is the order of magnitude of the measurement errors presented, among others, in Figures 2; and 6.
2. Taking into account the results of experiments and calculations the authors presented too modest interpretation in the "Conclusion". I propose to expand more boldly applications especially in practical use.

Author Response

Reviewer 1

“Phase formation, microstructure and magnetic properties of 2 Nd_14.5Fe_79.3B_6.2 melt-spun ribbons with different Ce and Y substitutions” by:  Q.J. Ke, F.L. Dai, S.X. Li, M.H. Rong, Q.R. Yao and J. Wang, deals with interesting approach to experimental studies of phase formation and microstructure of (Nd_1-2xCe_xY_x)_14.5Fe_79.3B_6.2 (x=0.05, 0.10, 0.15, 0.20, 11 0.25) alloys. The authors in this work, investigated phase structure, microstructure and magnetic properties of alloys.

In order to obtain the appropriate results, the authors used for the research following methods:  X-ray diffraction, SEM micrographs, and Magnetic measurements. In conclusion the authors concluded that (Nd_1-2xCe_xYx)_14.5Fe_79.3B_6.2 annealed alloys contain  the (NdCeY)₂Fe₁₄B phase with the tetragonal Nd₂Fe₁₄B-typed structure (space group  P42/mnm), α-Fe phase and rich-RE (α-Nd) phase. Also the tendency of magnetic properties of the ribbons could result from the co-substitution of Ce and Y for Nd in Nd₂Fe₁₄B phase and different phase formation.

I have gone through the manuscript and I recommend it for publication in Materials with the following reasons:

The paper is scientifically sound and of important interest.

The information presented in the paper is original and comprehensive.

The results and discussion sections were well-written and thorough.

Although the article is very interesting but before publishing requires a following addition:

1. What is the order of magnitude of the measurement errors presented, among others, in Figures 2; and 6.

Answer：Thanks for the reviewer’s suggestion. Crystal structure parameters of (NdCeY)₂Fe₁₄B phase were obtained using Jade software analysis and the errors of the parameters were determined after checked carefully the original data as shown in Figure 2. On the other hand, the experimental errors of magnetization curves measured by vibrating sample magnetometer (VSM) in Figure 6, are generally about 10^-7~10^-8 emu after Gaussian calibration, offset calibration, single-point calibration and multi-point calibration, and thus the maximum magnetic energy product without correction of demagnetization factor. Finally, Figure 2 was corrected considering the experimental errors, while Figure 6 was not updated. Please check them in the revised manuscript.

2. Taking into account the results of experiments and calculations the authors presented too modest interpretation in the "Conclusion". I propose to expand more boldly applications especially in practical use.

Answer：Thanks for the reviewer’s suggestion. We revised carefully the conclusion of the manuscript. Please check them in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript characterizes the phase structure, microstructure, and magnetic properties of Nd-Fe-B magnets.

The experimental work seems to be adequate, but the underlying motivation and why any of this matters is unclear.

Author Response

Reviewer 2

This manuscript characterizes the phase structure, microstructure, and magnetic properties of Nd-Fe-B magnets.

The experimental work seems to be adequate, but the underlying motivation and why any of this matters is unclear.

Answer：Thanks for the reviewer’s suggestion. We revised carefully the ‘Introduction’ and ‘Results and discussion’ sections of the manuscript in order to clearly show the motivation of this paper. Please check them in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper addresses the issues of structure formation and magnetic properties in the Ce/Y substituted Nd-Fe-B alloys. The study results are actual, original, and shed some light on the nature of structure formation in this rare-earth multi-component system. Nevertheless, I have some concerns about this version of the manuscript:

• The author insists that three different crystalline phases coexist in the annealed samples, while the direct SEM observations confirm only two of them. The explanation given in the text seems unconvincing. The volume fraction of the phase should be at least 2-3 % to be detectable via standard XRD, and this is enough to be seen with BSD.
• As the authors argue, fractions of Nd- and Fe-based phases in the melt-spun samples are reduced significantly compared with the annealed alloys, and additional CeFe2 phase revealed. All these structure observations for the ribbons should be supported by SEM/BSD images. Phase distribution and microstructure morphology are crucial to controlling the physical properties of these materials. I think that electron microscopy images will be useful for a more correct and rigorous interpretation of the magnetic results.

Author Response

Reviewer 3

The paper addresses the issues of structure formation and magnetic properties in the Ce/Y substituted Nd-Fe-B alloys. The study results are actual, original, and shed some light on the nature of structure formation in this rare-earth multi-component system. Nevertheless, I have some concerns about this version of the manuscript:

(1) The author insists that three different crystalline phases coexist in the annealed samples, while the direct SEM observations confirm only two of them. The explanation given in the text seems unconvincing. The volume fraction of the phase should be at least 2-3 % to be detectable via standard XRD, and this is enough to be seen with BSD.

Answer：Thanks for the reviewer’s comments. The authors agree with the reviewer’s option that the volume fraction of the phase should be at least 2-3 % to be detectable by XRD, which is enough to be observed in the SEM image. Thus, we checked carefully the XRD and SEM results again. It was confirmed that the XRD patterns of the annealed alloys contain two phases (NdCeY)₂Fe₁₄B and rich-RE(α-Nd) phase, while α-Fe phase was not found due to weak diffraction peaks (seen in Figure 1b), which is in agreement with the SEM results in Figure 3. The related expressions were corrected in the ‘Results and discussion’ section. Please check them in the revised manuscript.

(2) As the authors argue, fractions of Nd- and Fe-based phases in the melt-spun samples are reduced significantly compared with the annealed alloys, and additional CeFe2 phase revealed. All these structure observations for the ribbons should be supported by SEM/BSD images. Phase distribution and microstructure morphology are crucial to controlling the physical properties of these materials. I think that electron microscopy images will be useful for a more correct and rigorous interpretation of the magnetic results.

Answer：Thanks for the reviewer’s comments. The authors agree with the reviewer’s option. It is very useful that microstructure characteristics of the melt-spun ribbons were examined by SEM and TEM to confirm phase formation (e.g. CeFe₂) and phase fraction change in different samples. In fact, we have tried to carry out these experiments. However, we were failure to obtain good results due to the difficulty of sample preparation for SEM and TEM observation.

Author Response File: Author Response.pdf