Interfacial Stability of Additively Manufactured Alloy 625–GRCop-42 Bimetallic Structures
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors11. The quality of plots in the figures needs to be improved and be consistent throughout the manuscript.
22. In the Introduction section, the reason and application to perform the research on bimetallic structure between Alloy 625 and GRCop-42 needs to be provided and clarified.
33. In Introduction section, the scope of the work for his paper should be defined.
44. It is suggested to remove Table 1 from the Introduction section, or move it to Section 2: Materials and Methods
55. In section 2.1.1, please mark samples 1-5 in Figure 1 or make a schematic drawing show the locations of the five samples, or cuts.
66. Please add (a) and (b) in the pictures of Figure 2 and provide caption for each the photo. The scale bars are hard to read and please make them larger.
77. Please add the notation for A625 and GRCop-42 material in the joint in Figure 2, Figure 4… in the manuscript.
88. Please add the notation for A625 and GRCop-42 material in the joint in Figure 8 in the manuscript.
99. Figure 10 should be re-plotted to have a consistency on boundary, color, etc.
110. Please add (a) and (b) in Figure 11 and provide caption for each plot.
111. In the manuscript, the unit of the temperature was used F or C in different places. Please keep consistence.
112. The scale bars are almost invisible in the figures, Figure 4, 5, .. etc. Please fix them to make them visible.
113. The format of Figure 6 and 7 should be plotted as the same if the chemical compositions were measured in the same way.
114. Please add reference for the equations in Section 3.3.
115. Can it be further explained how Figure 16 shows the formation of Laves phase in A625?
116. Please make the crack initiation locations in Figure 22, 25, 28,32.
217. The structure of the manuscript needs to be improved. For example, you may consider to re-organize the Results and Discussion into two separate section to help the readers to understand the significance of the results.
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Comments on the Quality of English LanguageQuality of the English is good.
Author Response
Comment 1: The quality of plots in the figures needs to be improved and be consistent throughout the manuscript.
Response 1: Thank you for this suggestion. All of the plots have been adjusted to improve consistency as well as specific adjustments per other comments.
Comments 2 & 3: In the Introduction section, the reason and application to perform the research on bimetallic structure between Alloy 625 and GRCop-42 needs to be provided and clarified.
In Introduction section, the scope of the work for his paper should be defined.
Responses 2 & 3: Thank you for this suggestion. The introduction section has been expanded including additional information on applications and the scope of work.
Comment 4: It is suggested to remove Table 1 from the Introduction section, or move it to Section 2: Materials and Methods
Response 4: Thank you for this suggestion. We have, accordingly, moved the table into the materials and methods section.
Comment 5: In section 2.1.1, please mark samples 1-5 in Figure 1 or make a schematic drawing show the locations of the five samples, or cuts.
Response 5: Thank you for this suggestion. The figure 1 image has been replaced with an image with the cut locations marked. This image has been labeled with the corresponding sample numbers.
Comment 6: Please add (a) and (b) in the pictures of Figure 2 and provide caption for each the photo. The scale bars are hard to read and please make them larger.
Response 6: Agreed. I have added labels (a/b) in the images and the caption, and resized to make the scale bars more legible.
Comments 7&8: Please add the notation for A625 and GRCop-42 material in the joint in Figure 2, Figure 4… in the manuscript.
Please add the notation for A625 and GRCop-42 material in the joint in Figure 8 in the manuscript.
Responses 7 & 8: Thank you for the suggestion. The figures have been labeled with the corresponding material type (A625/GRCop-42).
Comment 9: Figure 10 should be re-plotted to have a consistency on boundary, color, etc.
Response 9: According to comment/response 1, this includes the figure 10 plot.
Comment 10: Please add (a) and (b) in Figure 11 and provide caption for each plot.
Response 10: Agreed. I have added labels (a/b) in the images and the caption.
Comment 11: In the manuscript, the unit of the temperature was used F or C in different places. Please keep consistence.
Response 11: C is used throughout, F is only added parenthetically for context, but never as a standalone, unnecessary additions of the parenthetical Fahrenheit conversion have been removed.
Comment 12: The scale bars are almost invisible in the figures, Figure 4, 5, .. etc. Please fix them to make them visible.
Response 12: The size has been increased and scale information added to the caption.
Comment 13: The format of Figure 6 and 7 should be plotted as the same if the chemical compositions were measured in the same way.
Response 13: Thank you for your comment. Figure 7 was reformatted to match figure 6.
Comment 14: Please add reference for the equations in Section 3.3.
Response 14: References have been added for the diffusion equations.
Comment 15: Can it be further explained how Figure 16 shows the formation of Laves phase in A625?
Response 15: Thank you for your comment. In response to another reviewer, figure 16 has been removed, but the formation of Laves phase is discussed in detail in discussion section 4.4.1 with details from the EPMA.
Comment 16: Please make the crack initiation locations in Figure 22, 25, 28,32.
Response 16: Thank you for this comment, the crack initiation locations have been marked.
Comment 17: The structure of the manuscript needs to be improved. For example, you may consider to re-organize the Results and Discussion into two separate section to help the readers to understand the significance of the results.
Response 17: Paper has been reorganized to split results and discussion into separate sections.
Reviewer 2 Report
Comments and Suggestions for Authors
The article titled "Interfacial Stability of Additively Manufactured Alloy 625—GRCop-42 Bimetallic Structures" investigates the properties and stability of bimetallic structures composed of two alloys fabricated using additive manufacturing methods: Alloy 625 (Inconel 625) and GRCop-42. These alloys are widely used in applications that demand high thermal and mechanical resistance, such as in the aerospace industry. This work is significant because it demonstrates how additive manufacturing can be used to produce high-performance bimetallic joints. It contributes to understanding how dissimilar metallic alloys interact under high-temperature conditions, which is crucial for applications in rocket engines, turbines, and other industries requiring long-term reliability.
Terminology Accuracy:
Using the name "Alloy 625" may lead to confusion, as it is less specific and does not immediately identify the material as the high-performance, trademarked nickel-based superalloy known as "Inconel 625." Replace all instances of "Alloy 625" with "Inconel 625" throughout the manuscript to ensure precision and align with standard terminology.
ABSTRACT:
Comment: While well-structured, the abstract lacks specific numbers and overly emphasizes methodology instead of highlighting the main findings.
Suggestion: Add quantitative information, such as material loss values, diffusion coefficients, or percentage reductions in mechanical properties after thermal exposure.
2. INTRODUCTION (PAGES 1-3)
Contextualization:
Comment: The introduction provides general examples of bimetallic structures and specific alloys but lacks details on the state of the art of additive manufacturing interfaces.
Suggestion: Expand the section on research gaps, emphasizing why previous studies have not addressed the combined behavior of 625 and GRCop-42 alloys.
Citations:
Comment: Some references are mentioned superficially without clear connections to the scope of the study.
Suggestion: Discuss in greater depth how studies like Gradl et al. (Reference [7]) influenced the choice of experimental conditions.
Justification:
Comment: The introduction mentions the relevance of the alloys for aerospace applications but does not clearly connect the expected results to potential improvements in those sectors.
Suggestion: Explicitly mention how this study could benefit the design of aerospace components exposed to high temperatures.
3. MATERIALS AND METHODS (PAGES 4-7)
Material Preparation:
Comment: The lack of technical details about the PBF-LB and DED printing parameters makes replication difficult.
Suggestion: Even if the parameters are proprietary, include a qualitative description of the processes, such as laser scan speed, controlled atmosphere, and type of powder used.
Thermal Treatment:
Comment: The choice of 816°C as the thermal exposure temperature is not justified.
Suggestion: Add an explanation based on the practical relevance of this temperature for aerospace applications.
Microscopy Analyses:
Comment: The use of EPMA is well-described, but the analytical methods (e.g., WDS and EDS) are not clearly tied to the characterization objectives.
Suggestion: Describe how composition maps inform the oxidation behavior and the formation of intermetallic phases.
Mechanical Testing:
Comment: The description of fatigue and tensile tests is insufficient to understand the impact of the results.
Suggestion: Add information about failure criteria, e.g., how fracture location influences the study’s conclusions.
4. RESULTS AND DISCUSSION (PAGES 8-21)
4.1. Oxidation of GRCop-42 Alloy (Pages 8-10)
Comment: The oxidation behavior of GRCop-42 is discussed but not sufficiently quantified.
Suggestion: Include a detailed table of material loss measurements over time, accompanied by high-resolution SEM images.
4.2. Diffusion (Pages 10-12)
Comment: Diffusion curves are presented, but the discussion is superficial.
Suggestion: Compare the predictions of Pandat software with the analytical models used (e.g., Fick’s laws), discussing the accuracy and limitations of both.
4.3. Microstructure and Phase Formation (Pages 13-15)
Comment: The formation of Laves phase and oxidation is addressed, but details on how these phenomena affect the interface are missing.
Suggestion: More explicitly relate microstructural changes to the observed mechanical properties.
4.4. Mechanical Properties (Pages 15-20)
Tensile Testing:
Comment: The section provides raw data but does not connect the results to microstructural changes.
Suggestion: Expand the interpretation of tensile strength results using figures such as 14 and 16.
Fatigue Testing:
Comment: Variability in the number of cycles to failure is presented without explanation.
Suggestion: Discuss whether factors like oxidation or Laves phase formation influence this variability.
4.5. General Discussion
Comment: The discussion lacks robust comparisons with the literature.
Suggestion: Include comparative tables with data from other relevant studies.
5. CONCLUSIONS (PAGES 22-23)
Comment: The conclusions are overly descriptive and repeat parts of the results.
Suggestion: Reframe to emphasize:
Key quantitative findings (e.g., diffusion coefficients and mechanical losses).
The specific contribution of the study to practical applications.
6. REFERENCES
Comment: Some references, such as [7], [13], and [27], are crucial but poorly explored in the text.
Suggestion: Revisit these sources to enrich the discussion.
Author Response
Comment 1: Terminology Accuracy: Change this back
Using the name "Alloy 625" may lead to confusion, as it is less specific and does not immediately identify the material as the high-performance, trademarked nickel-based superalloy known as "Inconel 625." Replace all instances of "Alloy 625" with "Inconel 625" throughout the manuscript to ensure precision and align with standard terminology.
Response 1: Thank you for this comment, however as you point out the name “Inconel” is a trademark, specifically originating from the International Nickel Company and now owned by Special Metals Corporation. As a general rule we avoid the use of trademarks in scientific writing even though we often use “Inconel 625” in conversation or informal communications. Our use of Alloy 625 is consistent with broader use in reference to alloys meeting the UNS06625 composition, and we note that common producers of this material such as Carpenter Technologies, Haynes International, and VDM Metals all avoid the use of the term Inconel. We have added a clarification that our use of the term Alloy 625 refers to UNS06625 and will keep with the generally used Alloy 625 identifier throughout.
Comment 2: ABSTRACT:
Comment: While well-structured, the abstract lacks specific numbers and overly emphasizes methodology instead of highlighting the main findings.
Suggestion: Add quantitative information, such as material loss values, diffusion coefficients, or percentage reductions in mechanical properties after thermal exposure.
Response 2: Agree. We have, accordingly, revised the abstract to add quantitative information. Added material loss measurements at 50 and 500 hours in line 14-15, added calculated diffusion coefficient values in line 20-21, and added the average percent reduction in yield strength after thermal exposure in line 23-24.
Comments 3: INTRODUCTION (PAGES 1-3)
Contextualization:
Comment: The introduction provides general examples of bimetallic structures and specific alloys but lacks details on the state of the art of additive manufacturing interfaces.
Suggestion: Expand the section on research gaps, emphasizing why previous studies have not addressed the combined behavior of 625 and GRCop-42 alloys.
Citations:
Comment: Some references are mentioned superficially without clear connections to the scope of the study.
Suggestion: Discuss in greater depth how studies like Gradl et al. (Reference [7]) influenced the choice of experimental conditions.
Comment: Some references, such as [7], [13], and [27], are crucial but poorly explored in the text.
Suggestion: Revisit these sources to enrich the discussion.
Comment: The introduction mentions the relevance of the alloys for aerospace applications but does not clearly connect the expected results to potential improvements in those sectors.
Suggestion: Explicitly mention how this study could benefit the design of aerospace components exposed to high temperatures.
Response 3: Thank you for your comments. The introduction has been expanded upon to state more explicitly the scope of work and emphasize the use of copper alloy-nickel alloy combinations and previous studies. Some previous studies, such as the Gradl et al. reference mentioned, discuss relevant applications for GRCop-42, but not continual use applications. We have provided additional references to examples from condensation heat transfer, solar concentrator and high-speed flight structures as examples where this type of material combination or similar might be used at this temperature for extended periods of time. The organization for which we performed this work has required us to remain silent on the specifics of the application, so we prefer to focus more specifically on the general materials capability.
Comment 4: Material Preparation:
Comment: The lack of technical details about the PBF-LB and DED printing parameters makes replication difficult.
Suggestion: Even if the parameters are proprietary, include a qualitative description of the processes, such as laser scan speed, controlled atmosphere, and type of powder used.
Response 4: Thank you for this suggestion. Unfortunately we performed this work on material that was provided by the work sponsor and are unable to share additional detail about the production process. In general, the parameters used for the additive manufacturing of both the PBF-LB GRCop-42 and LP-DED IN625 are standard parameter sets used for obtaining fully dense material of each alloy. By providing an overview of the porosity and microstructure of each material in the as-deposited condition, this will allow other researchers to make a comparative analysis of materials produced during any replication of the work, and those with expertise in the field can then make an informed determination as to whether the materials are equivalent or what might be the likely significance of variations between our material and those of other researchers.
Comment 5: Thermal Treatment:
Comment: The choice of 816°C as the thermal exposure temperature is not justified.
Suggestion: Add an explanation based on the practical relevance of this temperature for aerospace applications.
Response 5: Thank you for this suggestion. The particular temperature examined was dictated by the needs of the organization providing the funding and material for this work and corresponds to a representative 1500°F analysis point for an extended operational use case. This use case has practical relevance to use cases outside of rocket nozzle applications typical for this combination of materials. We have provided references to examples from condensation heat transfer, solar concentrator and high speed flight structures as examples where this type of material combination might be used at this temperature for extended periods of time. The organization for which we preformed this work has required us to remain silent on the specifics of the application, so we prefer to focus more specifically on the materials capability more generally.
Comment 6: Microscopy Analyses:
Comment: The use of EPMA is well-described, but the analytical methods (e.g., WDS and EDS) are not clearly tied to the characterization objectives.
Suggestion: Describe how composition maps inform the oxidation behavior and the formation of intermetallic phases.
Response 6: The results and discussion sections on the SEM/EDS analysis has been expanded upon. Additional composition maps as well as further analysis and discussion have been included.
Comment 7: Mechanical Testing:
Comment: The description of fatigue and tensile tests is insufficient to understand the impact of the results.
Suggestion: Add information about failure criteria, e.g., how fracture location influences the study’s conclusions.
Response 7: Additional failure information and discussion has been added to the analysis of the fracture surface. The description of the test setup is detailed in the methods section.
Comment 8: 4.1. Oxidation of GRCop-42 Alloy (Pages 8-10)
Comment: The oxidation behavior of GRCop-42 is discussed but not sufficiently quantified.
Suggestion: Include a detailed table of material loss measurements over time, accompanied by high-resolution SEM images.
Response 8: A table of material loss measurements was added (table 2). There are also optical microscopy images detailing the material loss and it’s measurement. Microprobe/SEM images/data regarding oxides in the copper alloy are also included on pages 10, 15, and 17.
Comment 9: 4.2. Diffusion (Pages 10-12)
Comment: Diffusion curves are presented, but the discussion is superficial.
Suggestion: Compare the predictions of Pandat software with the analytical models used (e.g., Fick’s laws), discussing the accuracy and limitations of both.
Response 9: The Fick’s law model is a calculation based on the measured composition data for the major constituents only, while the Pandat software makes a prediction purely based on the starting compositions, temperature, and time. I have added additional discussion in the modeling section to clarify these differences and limitations.
Comments 10: 4.3. Microstructure and Phase Formation (Pages 13-15)
Comment: The formation of Laves phase and oxidation is addressed, but details on how these phenomena affect the interface are missing.
Suggestion: More explicitly relate microstructural changes to the observed mechanical properties.
Tensile Testing:
Comment: The section provides raw data but does not connect the results to microstructural changes.
Suggestion: Expand the interpretation of tensile strength results using figures such as 14 and 16.
Fatigue Testing:
Comment: Variability in the number of cycles to failure is presented without explanation.
Suggestion: Discuss whether factors like oxidation or Laves phase formation influence this variability.
Comment: The discussion lacks robust comparisons with the literature.
Suggestion: Include comparative tables with data from other relevant studies.
Response 10: Thank you for your comment. Additional discussion on the relationship between the microstructural changes and observed mechanical properties has been added. Values are compared to three other relevant studies. Additional data has been added for robustness. Additional SEM/EDS have also been added to highlight this point.
Comments 11: CONCLUSIONS (PAGES 22-23)
Comment: The conclusions are overly descriptive and repeat parts of the results.
Suggestion: Reframe to emphasize:
Key quantitative findings (e.g., diffusion coefficients and mechanical losses).
The specific contribution of the study to practical applications.
Responses 11: Conclusions have been rewritten to address this comment as well as comments from other reviewers. The format has been changed and quantitative key findings have been emphasized along with some additional relation to practical applications.
Reviewer 3 Report
Comments and Suggestions for AuthorsRieffer and Wessman report on the interfacial stability of additively manufactured bimetallic structures composed of nickel-based alloy 625 and copper-based alloy GRCop-42. The study investigates the diffusion behaviour, thermal stability, and mechanical properties of the bimetallic interface after exposure to elevated temperatures of 816 °C for durations up to 500 hours. Using optical microscopy and electron probe microanalysis, the authors observed significant oxidation and material loss in the copper alloy, formation of oxides and Laves phase at the interface, and diffusion of alloying elements across the bondline. Mechanical testing, including tensile and fatigue tests, was performed on as-built and thermally exposed samples, revealing decreased strength and altered fracture behaviour after thermal exposure. Additionally, the study employs machine learning-based diffusion models and commercial diffusion software (Pandat) to predict diffusion coefficients, which were compared with experimental results.
The paper integrates advanced characterization techniques (e.g., SEM-EDS, EPMA) and computational approaches, offering insights into high-temperature bimetallic performance, critical for aerospace applications. However, the clarity of this study is highly hindered by disjointed results, insufficient additive manufacturing (AM) parameter details, and weak conclusions.
Major Corrections:
* The paper should restructure the results and discussion sections to enhance logical flow. Separating the presentation of results from their interpretation and ensuring that each subsection logically leads to the next will improve readability and comprehension.
* Many Figures and diagrams are of a poor quality and need clear formatting. Also the authors do not seem to structure the flow of the figures. Many of them could be part of a supporting information.
* More detailed information on the additive manufacturing parameters for both PBF-LB and DED processes should be included. Even if proprietary constraints exist, providing general parameters or discussing the influence of these parameters on the results is essential for reproducibility and validation.
* The conclusions should avoid bullet point style and be expanded to discuss the practical implications of the findings thoroughly. This should include the limitations posed by oxidation and diffusion at high temperatures, and potential solutions to mitigate these issues.
Minor Corrections:
* Line 11: Hyphenate "powder-based directed energy deposition."
* Line 49: Rephrase to: "Alloy 625 was deposited in powder form and fused by a laser."
Other Comments/Reminder:
The manuscript would benefit from significant improvements in editing and formatting to enhance its clarity and professionalism. Many figures and diagrams are of poor quality and lack clear formatting; organising these figures more effectively and considering moving some to supplementary material could improve the flow of the paper. It is essential for all authors to ensure that the manuscript meets academic standards in both content and presentation before submission.
Author Response
Comment 1: Minor Corrections:
* Line 11: Hyphenate "powder-based directed energy deposition."
* Line 49: Rephrase to: "Alloy 625 was deposited in powder form and fused by a laser."
Response 1: Agree. We have, accordingly, made these minor corrections.
Comment 2: The paper should restructure the results and discussion sections to enhance logical flow. Separating the presentation of results from their interpretation and ensuring that each subsection logically leads to the next will improve readability and comprehension.
Response 2: Thank you for your comment. The paper has been restructured to create separate results and discussion sections.
Comment 3: Many Figures and diagrams are of a poor quality and need clear formatting. Also the authors do not seem to structure the flow of the figures. Many of them could be part of a supporting information.
Response 3: Figures and diagrams have been reformatted, figures 16 and 17 have been removed since they presented information similar to what was available in figure 12 (previously figure 14). Reference to published data sets were also added to the data availability statement.
Comment 4: More detailed information on the additive manufacturing parameters for both PBF-LB and DED processes should be included. Even if proprietary constraints exist, providing general parameters or discussing the influence of these parameters on the results is essential for reproducibility and validation.
Response 4: Thank you for this suggestion. Unfortunately we performed this work on material that was provided by the work sponsor and are unable to share additional details about the production process. In general, the parameters used for the additive manufacturing of both the PBF-LB GRCop-42 and LP-DED A625 are standard parameter sets used for obtaining fully dense material of each alloy. By providing an overview of the porosity and microstructure of each material in the as-deposited condition, this will allow other researchers to make a comparative analysis of materials produced during any replication of the work, and those with expertise in the field can then make an informed determination as to whether the materials are equivalent or what might be the likely significance of variations between our material and those of other researchers.
Comment 5: The conclusions should avoid bullet point style and be expanded to discuss the practical implications of the findings thoroughly. This should include the limitations posed by oxidation and diffusion at high temperatures, and potential solutions to mitigate these issues.
Response 5: Thank you for your comment. The conclusions have been rewritten in paragraph form and expanded upon.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsNo further comments
Author Response
Comment 1: No further Comments
Response: Thank you for your input.
Reviewer 3 Report
Comments and Suggestions for AuthorsThanks for making corrections to the manuscript.
After reading the responses, this particular one makes me worried:
Response 4: Thank you for this suggestion. Unfortunately we performed this work on material that was provided by the work sponsor and are unable to share additional details about the production process. In general, the parameters used for the additive manufacturing of both the PBF-LB GRCop-42 and LP-DED A625 are standard parameter sets used for obtaining fully dense material of each alloy. By providing an overview of the porosity and microstructure of each material in the as-deposited condition, this will allow other researchers to make a comparative analysis of materials produced during any replication of the work, and those with expertise in the field can then make an informed determination as to whether the materials are equivalent or what might be the likely significance of variations between our material and those of other researchers.
If the alloy is not manufactured by you but by a company that has provided work (i.e. this was an industrial project), it will be very hard for any third person to reproduce the work or results you report unless those people obtain access to the same exact sample you have been working on. This is a problem from a point of reproducibility.
The only way one can go around it is if this work is structured and presented as a methodology paper, where the evaluation is not on the exact material but the combination of experimental and analytical techniques.
Author Response
Comment 1:
Thanks for making corrections to the manuscript.
After reading the responses, this particular one makes me worried:
Response 4: Thank you for this suggestion. Unfortunately we performed this work on material that was provided by the work sponsor and are unable to share additional details about the production process. In general, the parameters used for the additive manufacturing of both the PBF-LB GRCop-42 and LP-DED A625 are standard parameter sets used for obtaining fully dense material of each alloy. By providing an overview of the porosity and microstructure of each material in the as-deposited condition, this will allow other researchers to make a comparative analysis of materials produced during any replication of the work, and those with expertise in the field can then make an informed determination as to whether the materials are equivalent or what might be the likely significance of variations between our material and those of other researchers.
If the alloy is not manufactured by you but by a company that has provided work (i.e. this was an industrial project), it will be very hard for any third person to reproduce the work or results you report unless those people obtain access to the same exact sample you have been working on. This is a problem from a point of reproducibility.
The only way one can go around it is if this work is structured and presented as a methodology paper, where the evaluation is not on the exact material but the combination of experimental and analytical techniques.
Response 1:
We appreciate your comment and understand your concern. As the principal investigator for this work, please allow me to provide some additional context.
This work was performed as part of a larger project for which the sponsor required confidentiality. This required strict controls on information shared in the project even internally. To allow us the ability to support the project within the open environment of a university lab, it was agreed that the fundamental materials science around the interface stability would be considered open and publishable and that we would be able to work with excised samples from the provided pieces. To protect the confidentiality of the sponsor and their intellectual property, we were prohibited from disclosing any information regarding the sponsor identity, the application or end use, component geometries and manufacturing processes beyond simple identification of the processes used for each material. While the sponsor would have also preferred we remained silent on the processes, they accepted our argument that one with appropriate knowledge of metallurgy and manufacturing technology would be able to infer this from the microstructural information anyway, so the sponsor did agree to the generic description. While the goal of the project was not to develop new process parameters for either material and the parameters used were not novel, we must abide by our restriction against discussing the specific manufacturing process details per our agreement with the sponsor.
Having spent many years in industry and sponsoring university projects, I empathize with the sponsor’s need for confidentiality as I have placed similar restrictions on university partners myself. While this does lead to some lack of detail in the exact manufacturing process, in most cases some aspects of the work have been publishable with the perspective that it is better to contribute the knowledge to the community within the restrictions than not at all. One example from additive manufacturing is a paper by Varney et al. “Effects of Pore Geometry on the Fatigue Properties of Electron Beam Melted Titanium-6Al-4V”, Metallurgical and Materials Transactions A, Vol. 52. In this case the effects of porosity in electron beam powder bed titanium samples were evaluated, but the specific manufacturing anomaly leading to the porosity was not appropriate to describe publicly. While reviewers in that case also appropriately requested additional information, this was not possible and the manuscript was published in spite of this. In other instances, work I sponsored entailed manufacturing processes that were not able to be released publicly due to US export control laws and proprietary information concerns for processing companies. This is often the case with forged nickel superalloys for turbine engines- an example of this is Smith et al. “Phase transformation strengthening of high-temperature superalloys”, Nature Communications, 2016. In this case the article is by necessity completely silent on the processing of the material. Despite this, the article is very highly cited and represents significant new knowledge in the nickel superalloy domain, so there was significant value in publishing these results despite the difficulty that replicating this work would entail.
To the point of replicability or reproducibility- I agree with the reviewer that author’s should do their utmost to provide the community with as much information as possible to enable others to evaluate their work or further it. In this case, I would contend that were I trying to reproduce this work if made by another, the information presented here would allow me to do so. By having knowledge of the general process used, alloy chemistries and resulting defect content and microstructure, the reader would be aware of the material evaluated through the listed thermal exposures. However, one major difficulty with replicating the work of others today in additive manufacturing is the lack of consistency from machine manufacturer to another or even between individual systems of the same model. So, in reproducing this work it might be the case that there would be slight differences in processing parameters between our systems and others to arrive at that same result. Conversely, others with the same equipment and alloy and even given the same processing parameters might arrive at a slightly different result. While we agree on the need to provide information to enable reproduction, at the current level of maturity in the AM world this will not be perfect and we ask that there be some allowance for variations in approaches to this, as has often been the case across a number of domains in metallurgy and manufacturing.
It is my hope that this additional perspective helps to somewhat allay your concerns.
Thank you,
Andrew Wessman, Assistant Professor, Department of Materials Science and Engineering, University of Arizona
Round 3
Reviewer 3 Report
Comments and Suggestions for AuthorsI appreciate Dr. Wessman's response and the clarification provided. The work is highly relevant to the journal, and I believe it deserves publication.
However, I would like to suggest that, prior to publication, the authors focus on enhancing the formatting of their figures, particularly the diagrams, to ensure they meet the journal's publication standards. While the current diagrams might be adequate for presentations or conference proceedings, journal submissions require a higher standard of quality.
To support this, I have included two relevant publications below that the authors can reference to improve their figures before the final acceptance.
https://www.sciencedirect.com/science/article/pii/S0264127522006578
https://www.cell.com/heliyon/fulltext/S2405-8440(24)04710-8
Author Response
Comment: However, I would like to suggest that, prior to publication, the authors focus on enhancing the formatting of their figures
Response: Thank you for your comment. The figures have been further revised.
