Functionally Gradient Material Fabrication Based on Cr, Ti, Fe, Ni, Co, Cu Metal Layers via Spark Plasma Sintering
, Evgeniy K. Papynov 1, Igor Yu. Buravlev 1, Anastasiya A. Buravleva 1, Sergey V. Chuklinov 2, Ekaterina A. Gridasova 1, Anton V. Pogodaev 1, Valreiia A. Nepomnyushchaya 1, Zlata E. Kornakova 1, Alexey O. Lembikov 1, Danila V. Gritsuk 1, Olesya V. Kapustina 1, Sofia S. Gribanova 1 and Yun Shi 3,4Round 1
Reviewer 1 Report
Please see the comment file.
Comments for author File: 
Comments.pdf
Author Response
response to the reviewer in the attached file
Author Response File: 
Author Response.docx
Reviewer 2 Report
1/The quality of all figures is poor and should be improved.
2 / EDX spectra should be provided.
3/ The average particle size values extracted from fig.1 should be provided in the text. More explanations about the diffrence in the values should be provided.
4/ More details about the microhardness Hv determination should be added.
5/The discussions should be improved.
Author Response
response to the reviewer in the attached file
Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript is entitled "Functionally-gradient material fabrication based on Cr, Ti, Fe, Ni, Co, Cu metal layers via spark plasma sintering". The research topic interesting, and the sample fabricated is beautiful. However, the manuscript needs to be better organized and lack important experiments and discussions. Therefore, in the current form, the paper is not qualified for publication.
1. Line 81-82, make the meaning of the following sentence clearer: "In addition, the key role is played by the technologies of FGM or FGC production, the number of which is diverse [1,4,15]."
2. Line 91-92. "It should be noted that the number of studies on the application of SPS for the formation of coupled-type FGM is very limited" How limited? It is suggested that a detailed literature review be concluded in the introduction part about fabrication of FGM with SPS method.
3. Delete the content from Line 103 to Line 105.
4. In the "Materials and Methods" section, Line 109-113, how were the powders put into the mold? Were they cold pressed or mixed? Please indicate the detailed procedure.
5. Line 123-136, the "Characteristics of the research methods" section needs to be improved. How were the sample surfaces treated before SEM tests? The goal of stirring of powders is not clearly illustrated, is this for XRD tests?
6. Line 138, "IPS technology" to "SPS technology".
7. In Fig. 3, the two green arrows may lead to misunderstanding.
8. The authors show many phase diagrams. Here is the question, SPS is a relatively fast heating and cooling process, which may be away form equilibrium state, how can the phase diagrams be enough to explain the observations above?
9. Some further tests no the FGM sample should be performed. For example, thermal stability, the intermetallics may play a critical role in the thermal stability.
10. Overall: The authors did do many research work. However, this paper needs to be better organized and the research needs to be better planned. And the language of the paper needs to be further polished. More discussion should bed added.
Author Response
response to the reviewer in the attached file
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors tried to reply to the addressed comments during the first revision but the discussions still need improvement with more comparison with previous recent works.
Author Response
1 The authors tried to reply to the addressed comments during the first revision but the discussions still need improvement with more comparison with previous recent works.
The authors agree that the extension of the comparative description for different methods is useful. However, this paper is not a review article and the purpose of the study is an experimental research problem, but with regard to the world's known works on this research topic, some of which are presented in the introduction. At the same time, the formation of this particular FGM identical composition by similar or other methods is not described in the literature. No information is available. In this regard, the work has an obvious novelty, the significance of the results obtained does not depend on a comparative literature analysis, and can be presented to the scientific community. We respectfully request the reviewer to take this into account and give his consent to the possible publication of these results in their current form.
Reviewer 3 Report
The authors sent back the responses quickly, and the questions were all answered. However, the reviewer still has concerns about this paper.
1. Clear according to Fig. 2, the FGM has layered structure with pure metal in each layer. In this case, what is the point of ball milling? In addition, the authors need to illustrate clearly how the different powders were put into the sintering mold sequentially?
2. For the XRD tests, the authors stated that the tests were performed on the cut cross section. Since we have five different boundaries. How did the authors separate the different boundaries as shown in Fig. 4? The reviewer is assuming that the authors cut each boundary and performed individual test rather than the whole cross section.
3. Discussion is still not enough for this manuscript, which makes this manuscript more like a technical report rather than a journal paper.
4. Phase diagrams are not proper to explain the observations. The sintering temperature was 900 degree C, but the discussions have many temperatures above 1000 degree C.
The reviewer do not think the paper is qualified for publication. Wish the authors best of luck.
Author Response
The authors sent back the responses quickly, and the questions were all answered. However, the reviewer still has concerns about this paper.
- Clear according to Fig. 2, the FGM has layered structure with pure metal in each layer. In this case, what is the point of ball milling? In addition, the authors need to illustrate clearly how the different powders were put into the sintering mold sequentially?
It is indicated in the text of the paper that the ball mill was used only in the case of samples for XRD analysis. The methodology of the experiment is described in detail in the experimental part. This experiment was carried out to determine the possibility of intermetallide phases formation in the alloys, which represent the basis of the FGM layers. In order to obtain FGM the layers were placed in the following order Cr-Ti, Fe, Co, Ni, Cu (in the specified order from the bottom to the top vertically). This refinement was added to the experimental part.
- For the XRD tests, the authors stated that the tests were performed on the cut cross section. Since we have five different boundaries. How did the authors separate the different boundaries as shown in Fig. 4? The reviewer is assuming that the authors cut each boundary and performed individual test rather than the whole cross section.
It is indicated in the text of the paper that the XRD was not taken from a ready sample of FGM. The XRD was taken from separately made samples of alloys of each metal pair. For a more detailed description, we return the description of the XRD experiment presented earlier in version 1 of the paper:
XRD analysis of the samples was carried out on a multipurpose X-ray diffractometer D8 Advance "Bruker AXS" (Germany), CuKα-radiation, Ni-filter, average wavelength (λ) 1.5418 Å, shooting angle range 10-80°, scanning step 0.02°, spectra registration rate - 5 °/min. For the XRD, samples were prepared based on two metal components that correspond to the boundary layers (Cu-Ni, Ni-Co, Co-Fe, Fe-Ti, and Ti-Cr). Powders were initially stirred in a 700 rpm planetary mill for 10 min for each mixture and then sintered in SPS conditions at 900 °C for Cu-Ni, Ni-Co, Co-Fe, Fe-Ti and 1200 °C for Ti-Cr (heating, holding, pressing and cooling regimes similar to those for FGM production). XRD imaging was performed from a cross-polished section for each sample (each metal pair).
- Discussion is still not enough for this manuscript, which makes this manuscript more like a technical report rather than a journal paper.
The team of authors considers that the reviewer's remark is unfair since the reviewer does not make any arguments about the untenability of the paper, but only expresses his individual opinion. This assumption is also confirmed by other comments of this reviewer, which indicate that the reviewer has not carefully read the paper and has overlooked all the necessary information.
We draw the editor's attention to the fact that in the objective opinion of the authors, as well as of two other reviewers, this paper is a scientific article even taking into account its technical orientation. The study includes a reliable set of experimental data and their discussion. The conclusions presented in the paper meet the goal of the research, have scientific novelty and significance, as well as have practical relevance. The set of applied methods is modern, broad, reliable. The paper contains scientific information, which is also confirmed by other reviewers, which may be of interest to the scientific community, despite its technical orientation.
The authors propose to make the final decision to the editor based on the opinion of all reviewers of this paper. Otherwise, the authors are ready to immediately withdraw the paper and decide not to publish it in this journal.
- Phase diagrams are not proper to explain the observations. The sintering temperature was 900 degree C, but the discussions have many temperatures above 1000 degree C.
This observation is not valid. The phase diagrams reflect a wide range of temperatures, as shown in Figure 5. 5.
