Laser–Direct Current arc Hybrid Additive Manufacturing of Cu-Cr-Zr Alloy: Microstructure Evaluation and Mechanical Properties

Round 1

Reviewer 1 Report

The topic of the article is very interesting and is in line with the goals and scope of the journal. The article is well-structured and written. I suggest revising the article based on the comments below.

 

1. The keyword "Laser- direct current arc hybrid additive manufacturing" is too long to split into two parts.

 

2. The research objectives are not clearly defined at the end of the introduction, and the research questions that will be answered by the results of this work are not stated. The authors must clearly state how the contribution of this work differs from work already done in this field. The introduction should conclude with some hypotheses, main conclusions, and scientific contributions to other studies in the field.

 

3. The literature review in the introduction needs to be supplemented with a literature section. It would be nice if the authors could substantiate some results from previous research.

 

4. In figure 7, add the subfigure (d) and the corresponding description

 

5. In Figure 8, indicate the position of subfigures (a), (b), and (c) described in the caption of Figure 8

 

6. In Figure 9, indicate all the subfigures shown and their description

 

7. In Figure 10, the last subfigure is neither labelled nor described; add this information in the caption

 

8. In the caption of Figure 12, subfigures d, e, and f are missing. Also enlarge the scale in Figure 12. When the article is printed, it's very difficult to see the scale in each subfigure

 

9. The diagrams shown in Figure 11 need to be revised and corrected. After fracture of the specimen, the relationship between stress and strain is represented by a straight line. This straight line results from the free movement of the claw of the testing machine and doesn't represent the response of the material to the required load; in this sense, these areas of the diagram in the end zone must be removed from the diagrams in Figure 11.

 

10. Conclusions should be updated with current work constraints and future improvements.

 

As for the quality of the English language, I found no major problems, I recommend a final revision of the text.

Author Response

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Reviewer 2 Report

This work reports the preparation of Cu-Cr-Zr precipitated alloys by a laser-direct current arc hybrid additive manufacturing, with special consideration to the morphology and mechanical strength study of the alloys obtained at various laser powers. The materials were characterized by SEM, TEM, HRTEM, XRD, and tensile strength. Results indicate the higher laser power investigated yielded alloys with the highest values for ultimate tensile strength, which was significantly greater than for alloys having prepared by traditional methods. The current method is promising for scaling up and the fundamental properties of the materials should appeal to a broad audience of materials scientists in the filed of precipitated alloys and of additive manufacturing. My only comment is that authors correct the definition of the "b" parameter in equation 4. They named it the Bergh vector, where this should be the Burgers vector. I have no further comments and recommend the manuscript for publication once this minor issue is addressed.

Author Response

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Reviewer 3 Report

A major revision needs for this manuscript based on some issues. Other comments could be found as follows,

1)      It is better to use “evaluation” instead of “evolution” in the article title.

2)      In the abstract, no sentences could be found for the research method. Only highlighted results must be reported.

3)      The first keyword is lengthy. It is two words.

4)      The novelty must be highlighted in the introduction, compared to the literature review.

5)      All formulations need references.

6)      It is not clear how values were selected in Table 1. References must be added. Moreover, two parameters were changes in 1, 2, and 3! Then, how could the authors find the difference between results for various values of scanning speed and heat input. It is better to have a design of experiments.  

7)      More details of process parameters must be reported with references.

8)      In the title of Figure 2, the heat input should be mentioned for the values. Moreover, the size of three images in this figure is not similar! Why? They must be similar.

9)      The mentioned issue could be seen for Figure 3, for (a) and (b), compared to (c).

10)  More discussions should be added to the results of XRD and TEM. In general, the discussion must be extended by comparing results to other results of other articles.

11)  The EDX analysis must be done for Figure 6 to prove the claim of Cr phase.

12)  The size of Figure 8 must be enlarged. The scale bar is not clear what it is.

13)  The background color of Figure 11 should be white. The quality is not proper and they must be enlarged below each other, instead of besides each other.

14)  It is better to add the elastic module to Table 2. The size of the fonts is not proper in the title of this table.

15)  The value of “311” in Table 3 must be changed to “311.3+/-7.8”.

16)  The size of Figure 12 must be enlarged. Again, in the title of this figure, the heat input should be mentioned.

17)   “Conclusion” must be changed to “Conclusions”. Moreover, it must be rewritten one by one, in bullets to show the novelty.

18)  The number of references must be extended and updated based on recent articles, published in 2017-2023.

19)  What is the novelty of this article compared to the following link?

 

*https://scholar.google.com/scholar?hl=en&as_sdt=2007&q=Laser-direct+current+arc+additive+manufacturing+of+Cu+alloy&btnG=

Author Response

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Reviewer 4 Report

The paper entitled “Laser-direct current arc hybrid additive manufacturing of Cu-Cr-Zr alloy: Microstructure evolution and mechanical properties " focuses on Laser-direct current arc hybrid additive manufacturing to fabricate the Cu-Cr-Zr alloy in this research From my point of view, the topic is of great interest. But some minor comments:

·        Begin the abstract by briefly explaining the significance or motivation behind the research.

·        The introduction could be improved by providing a clear statement of the novelty and objective of the study.

·        Some sentences in the paper are too long and may be confusing for readers. Breaking them into shorter sentences would help to improve comprehension.

·        I would have liked the author to add analysis on the effect of transfer modes on the wall manufacture, something similar to what we have seen in recent articles. (As examples  http://doi.org/10.3390/sym13071245 or https://doi.org/10.1080/02670836.2018.1455012) and some modelling of thin wall results (https://doi.org/10.3390/met11050678 or https://doi.org/10.1016/j.commatsci.2011.06.023)

·        I would suggest the author to include a real image of the experimental setup in the paper.

 

·        Discuss the influence of precipitates on mechanical properties: Provide insights into the effects of submicron and nanoscale Cr precipitates, as well as the observed presence of Zr precipitates, on the mechanical properties of the Cu-Cr-Zr alloy. How do these precipitates contribute to strengthening or other mechanical behaviors?

·        Contextualize the maximum ultimate tensile strength and elongation values: Relate the achieved maximum ultimate tensile strength of 311.3 ± 7.8 MPa and elongation of 38.6 ± 5.6% to the existing literature or comparable alloys. Discuss the significance of these values in terms of the potential applications and performance of the Cu-Cr-Zr alloy fabricated through laser-direct current arc hybrid additive manufacturing. Also Stress-Strain curve shape.

·        Improvements could be made to Figure 11 in terms of quality.

·        Please pay attention to the formatting of the paper as it appears to be lacking in certain areas. For instance, on line 272, the column width is incorrect, and on line 289, there are texts of varying sizes.

·        I kindly request that you present the conclusions of the study in bullet points, accompanied by future lines of research. This format will allow for a concise and organized summary of the key findings and potential areas for further investigation.

The research topic presented in the paper undoubtedly interesting. The investigation of laser-direct current arc hybrid additive manufacturing of the Cu-9 Cr-Zr alloy, with a focus on the evolution of microstructure and mechanical properties, holds great potential for advancing our understanding of this alloy's behavior and performance. While the content of the paper appears to be robust and impactful, there is room for improvement in terms of style and formatting. With the necessary refinements, this paper has the potential to make a significant contribution to the field of additive manufacturing and the development of high-performance alloys.

Author Response

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Round 2

Reviewer 1 Report

After analyzing the revised version of the article " Laser-direct current arc hybrid additive manufacturing of Cu-Cr-Zr alloy: Microstructure evaluation and mechanical properties", it can be stated that the authors have significantly improved the article. In this sense, I believe that the article in the revised version meets the necessary requirements to be published in the jornal coatings.

Sincerely,

Minor editing of English language required

Author Response

Thank you for your kind comments.

Thanks again to the reviewers for the detailed and extremely helpful comments, which are of great guiding significance in improving the quality of our manuscripts and conducting further research. We hope that the revised manuscript can meet your requirement.

Reviewer 3 Report

Still, it needs a major revision based on the following comments,

1) The research method is not added to the abstract. The research method is details about testing and fabrication techniques.

2) The novelty is not highlighted in the introduction. Firstly, a conclusion should be made on the literature and then, the innovation of this work must be mentioned, compared to the literature. 

3) For Table 1, it must be clearly mentioned in the text that the main parameter is the scanning speed and the other one (heat input) is not the main variable and it is calculated by Formulation 1. 

4) The discussion is still poor. The discussion is not only to describe the behavior and it must be compared to other results of other articles. Without mentioning references to the reason for the material behavior, this manuscript is not acceptable. 

5) The comment about the elastic module is not addressed. It is not related to the yield point and other methods could be used for the evaluation such as the line of 0.2%-offset for the strain. Please check the approaches for measuring the elastic module. 

6) The comment of "The value of “311” in Table 3 must be changed to “311.3+/-7.8”. " is not addressed. 

7) The conclusions must be written one by one, in bullets to show the novelty. The first sentence should be general information about the topic and then, highlighted results must be presented in bullets, one by one. 

 

Author Response

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Author Response File: Author Response.docx