Dear Dr. Yong,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

Please submit your revised manuscript by May 09 2026 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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Hari Murthy, Ph.D.

Academic Editor

PLOS One

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Yes

Reviewer #4: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

Reviewer #4: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

Reviewer #4: No

**********

Reviewer #1: The current review investigates the effect of laser power on the microstructure and properties of deposited AlTi coating on TC4 Titanium alloy using the selective laser melting technique. The title is attractive, and the manuscript is well written and organized. However, there are some issues to be considered as follows:

- The abstract is relatively too long (it exceeds 300 words); it should be reduced to be more concise and focused within 200 words.

- The authors refer to SLM as "laser selective melting"; that expression should be replaced by "selective laser melting" throughout the manuscript text.

- The problem statement should be defined in more detail by the end of the introduction section.

- The AlMgSc Powder characterization should be presented in more detail.

- Figure 2 should be informative and indicative; the authors should label the observations and the samples according to the applied power.

- The SEM image scale should be readable in all Figures related to microscopic analysis.

- In Figure 8, the resolution of the hardness plot should be improved, in addition to adding the standard deviation of the measurement values.

- There should be a table comparing the current study results to those obtained in the literature using the proposed technique or other techniques to justify the obtained results and analysis.

- The authors should illustrate the limitations of the proposed technique, as it is limited to flat surfaces and not applicable to complex geometries.

- The conclusion should focus on the novelty and main contributions, in addition to the future perspective.

- Another review round is highly recommended after considering the above comments and recommendations.

Reviewer #2: This manuscript presents a relevant and practically valuable study in the field of surface engineering of titanium alloys for aviation applications. The authors systematically demonstrate the effect of laser power variation (350–380W) on the microstructure, phase composition, elemental distribution, and microhardness of TiAl coatings formed via Selective Laser Melting (SLM) on TC4 substrates. The key finding that 370W is the optimal power level, yielding good metallurgical bonding and a maximum hardness of 641.9 HV0.2, represents a useful contribution as a process reference baseline. However, several substantial aspects require strengthening before this manuscript is suitable for publication.

1. The authors test only four laser power levels (350W, 360W, 370W, 380W) at 10W intervals without providing adequate scientific justification for why this specific range was selected. It is not explained why powers below 350W or above 380W were not investigated. With only four data points, it is difficult to draw robust conclusions about the causal relationship between laser power and coating quality. The authors are advised to either expand the testing range or provide strong thermodynamic and metallurgical reasoning explaining why the 350–380W domain was chosen as the investigation window.

2. There is a fundamental inconsistency in this manuscript: the title and main claims refer to a TiAl coating, yet the powder material used is AlMgSc (an aluminum alloy), not a TiAl powder. The TiAl intermetallic phases (TiAl, TiAl_2, Ti_2Al, TiAl_3, Ti_3Al, Ti_5Al_11) form in-situ through reactions between Al from the AlMgSc powder and Ti diffusing from the TC4 substrate. The authors must explicitly distinguish between the bulk coating (AlMgSc) and the interfacial reaction zone (TiAl intermetallics), and revise the terminology throughout the manuscript to avoid misleading readers.

3. The authors invoke the Gibbs free energy equation (ΔG = ΔH − TΔS) to explain the phase formation mechanism at each laser power level. However, not a single numerical value of ΔG, ΔH, or ΔS is presented to support these arguments. Statements such as "ΔG < 0 and sufficient nucleation driving force" without quantitative thermodynamic calculations render these arguments highly speculative. The authors are strongly advised to perform thermodynamic calculations using CALPHAD-based software (e.g., Thermo-Calc or FactSage) or to cite quantified literature data for each reported phase to substantiate their mechanistic claims.

4. The manuscript's central claim is that the coating provides surface protection for titanium components in aviation applications, yet the only mechanical test performed is Vickers microhardness. No wear resistance (tribology), adhesion/scratch test, high-temperature oxidation resistance, or corrosion resistance data are presented. Given the claimed application in demanding aerospace engine environments, the authors are strongly advised to add at minimum quantitative adhesion testing (e.g., pull-off or scratch test) and wear resistance testing to substantiate the engineering relevance they claim.

5. Although 10 hardness measurement points per test group are mentioned, hardness values are reported as single numbers without standard deviation or confidence intervals. Similarly, coating thickness values (937.5 µm; 789.5 µm; 812.5 µm; 831.6 µm) appear to be single measurements. The number of replicate specimens per power condition is not stated. The authors must include statistical analysis (mean +/- SD) for all quantitative data and clarify the number of experimental replicates to ensure the reproducibility and statistical validity of their findings.

6. Table 3 presents EDS data in weight percent (Wt%), yet the entire discussion uses atomic ratios for Al/Ti (24:1; 1:1.5; 1:1.8; 4:1) without showing any transparent conversion steps. Converting from weight percent to atomic ratio depends on the atomic mass of each element and must be shown explicitly. Furthermore, the Methods section states that line scanning analysis EDS was performed to determine the distribution of Ti, Al, Mg, and Sc across the interface transition zone, yet these line scan profiles are absent from the Results section. The authors must present complete EDS line scan profiles and add an atomic percent column to Table 3.

7. The data show that coating thickness decreases from 937.5 µm (350W) to 789.5 µm (360W), then increases again to 812.5 µm (370W) and 831.6 µm (380W). This non-monotonic pattern is counterintuitive, the lowest power (350W) produces the thickest coating, while higher powers yield thinner coatings. The authors provide no satisfactory mechanistic explanation for this phenomenon. Factors such as material evaporation, sputtering at higher powers, or differential melt pool penetration depth need to be explicitly discussed. It should also be clarified whether these thickness values are averages from multiple measurements or single-point measurements.

8. There is a significant labeling error in the manuscript. In Figure 2, the caption reads "(8) 350W" when it should read "(d) 380W". Additionally, the name "Yong Li" appears twice in the author list (as both the 3rd and 4th author), which is an administrative error that requires immediate correction. The authors are also advised to improve the resolution of SEM and XRD figures and ensure consistent label formatting across all figures to meet PLOS ONE publication standards.

9. The authors claim that this study provides "a new method and theoretical basis for protective coating preparation", yet there is no systematic discussion of what distinguishes this work from previously published studies on similar topics. Many of the cited references (particularly references 29–52) are general SLM papers with little direct relevance to the TiAl/TC4 system. The authors are advised to conduct a more focused literature review specifically on TiAl coating systems on titanium substrates, explicitly articulate the specific contribution of this study relative to the existing body of knowledge, and replace peripheral references with literature more directly relevant to the research topic.

Reviewer #3: Article Review

Effect of Laser Power Variation on Microstructure and Properties of Selective Laser Melting Coatings Deposited on TC4 Titanium Alloy

In this article titled “Effect of Laser Power Variation on Microstructure and Properties of Selective Laser Melting Coatings Deposited on TC4 Titanium Alloy,” the authors presented a study coating formation using laser selective melting (SLM) technology on the surface of titanium alloy, focusing on the effects of different laser powers of 350-380W on the performance of TiAl coatings formed by SLM on titanium alloy surfaces. This study seems to be a useful contribution to the literature, and it can be accepted after addressing the following minor issues:

1. The abstract should be improved to enhance flow and to provide the literature gap and the importance of this study. It should be more reader-friendly for general readers, using easy and non-technical words, and should be more self-explanatory.

2. The Keywords should be revised to include more relevant keywords and should not include abbreviations only to improve the searchability of the article. For better Search Engine Optimization and searchability, more focused keywords should be included while keeping the abbreviations if necessary.

3. Some references are incomplete; please recheck to include all information.

4. The English language flow in this manuscript should be improved. It should also be more detailed.

5. The relevance of process, tool and equipment and the variables and reasoning for specific parameters used is not mentioned in detail.

6. Coherent terminologies should be used, like figure or fig, throughout the whole manuscript.

7. The motivation behind this study should be included with more detail, and it should be in proper flow, introducing the gap and research question.

8. The suppositions and boundary conditions should be explicitly declared.

The End

Reviewer #4: This manuscript investigates the effect of laser power (350–380 W) on the microstructure and mechanical properties of coatings fabricated on TC4 titanium alloy via selective laser melting (SLM). The authors employ SEM, EDS, XRD, and microhardness testing to characterize coating morphology, phase composition, elemental distribution, and hardness evolution. The results show that laser power significantly affects coating quality: low power (350–360 W) leads to insufficient melting and severe cracking, an intermediate power (370 W) produces optimal metallurgical bonding and the highest hardness (~642 HV), and high power (380 W) causes overheating and renewed cracking. The study is experimentally straightforward and addresses a practically relevant topic, and the observed trends are generally consistent and reasonable. However, the work is largely incremental with limited novelty, the mechanistic discussion lacks quantitative support, the material system description is inconsistent (TiAl vs. AlMgSc), and the overall rigor and presentation quality are insufficient.

Recommendation: Major revision

Major issues:

(a) Lack of novelty: The influence of laser power on SLM microstructure and properties is already well established. The manuscript mainly confirms known trends without providing new insights or deeper analysis. The authors should better justify the novelty and significance of this work.

(b) Confusion in material system: The manuscript refers to “TiAl coatings,” while the feedstock material is AlMgSc powder. This inconsistency appears in the Abstract, Introduction, and Results (especially Section 3.2), and creates confusion regarding the coating composition and phase evolution. This issue must be clarified throughout the manuscript.

(c) Weak mechanistic analysis: The discussion relies heavily on qualitative thermodynamic arguments (e.g., Gibbs free energy), but no quantitative calculations, phase diagram analysis, or supporting data are provided. The explanation remains speculative and should be strengthened or simplified.

(d) Insufficient statistical rigor: Microhardness results are presented without error bars, standard deviation, or repeatability analysis. The use of only 10 data points is insufficient to demonstrate reliability. Similar lack of quantification exists for microstructural features.

(e) Limited performance evaluation: The study focuses on microstructure and hardness only. For a coating study, additional performance metrics such as wear resistance, adhesion strength, or oxidation/corrosion behavior are expected.

(f) Overstated claims: Statements such as “provides a new method” and “important engineering application value” are not adequately supported and should be moderated.

Specific technical issues:

(a) Energy density equation (Section 3.1): The equation and parameter definitions are unclear and not fully consistent with standard notation. Please clarify symbols and units.

(b) Phase identification (Section 3.2): Multiple phases are reported without detailed peak indexing or reference patterns, making the identification unclear.

(c) EDS results (Section 3.2, Fig. 7, Table 3): Reported atomic ratios (e.g., Al/Ti = 24:1) appear extreme. The authors should clarify whether these values are averaged and discuss measurement uncertainty.

(d) Hardness discussion (Section 3.3): The explanation linking hardness to “binding energy of intermetallic compounds” is vague and lacks quantitative support.

Formatting issues:

(a) Figure 2 caption: “(8) 350W” appears incorrect and should likely be “(d) 380W”.

(b) Inconsistent figure labeling across the manuscript.

(c) Table 1 formatting is unclear, with misaligned columns.

(d) Table 3 lacks clear explanation of sample numbering (1–4).

(e) Inconsistent unit formatting (e.g., µm vs. um, spacing issues, HV0.2 notation).

(f) Repetition of similar explanations across Sections 3.1–3.3.

Language and grammar issues (selected examples):

(a) Abstract: “the phases of Ti5Al11 and Al2Sc are added on the basis of 360W” → unclear and grammatically incorrect.

(b) Introduction: “demonstrate a wide range of applications” → should be simplified to “are widely used.”

(c) Section 3.1: Several sentences are overly long and difficult to follow.

(d) Section 3.2: Thermodynamic discussion contains grammatical errors and inconsistent tense usage.

(e) General issues: Missing articles, singular/plural inconsistencies, and repetitive phrasing (e.g., “at this point,” “at the same time”).

(f) The manuscript requires substantial English editing for clarity and readability.

**********

what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes: Ali Raza Shafqat

Reviewer #4: No

**********

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Dear Dr. Yong,

Please submit your revised manuscript by Jul 18 2026 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

• A letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

As the corresponding author, your ORCID iD is verified in the submission system and will appear in the published article. PLOS supports the use of ORCID, and we encourage all coauthors to register for an ORCID iD and use it as well. Please encourage your coauthors to verify their ORCID iD within the submission system before final acceptance, as unverified ORCID iDs will not appear in the published article. Only  the individual author can complete the verification step; PLOS staff cannot  verify ORCID iDs on behalf of authors.

We look forward to receiving your revised manuscript.

Kind regards,

Hari Murthy, Ph.D.

Academic Editor

PLOS One

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

Additional Editor Comments:

Most of the reviewer comments has been addressed satisfactorily to a great extent- however there is still some ambiguity regarding the technical content and the paper in its current form is not yet publishable. Request you to kindly go through the reviewer comments and make necessary changes.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #4: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: No

**********

Reviewer #1: (No Response)

Reviewer #2: (No Response)

Reviewer #4: The manuscript entitled “Effect of Laser Power Variation on Microstructure and Properties of Selective Laser Melting Coatings Deposited on TC4 Titanium Alloy” investigates the influence of laser power on the formation quality, microstructure, phase composition, elemental distribution, and hardness of coatings fabricated on TC4 titanium alloy substrates using selective laser melting (SLM). The authors employed SEM, EDS, XRD, and microhardness measurements to compare coatings fabricated under laser powers ranging from 350 W to 380 W. The results indicate that insufficient laser power leads to incomplete melting and severe cracking, while excessive power causes overheating-induced cracking, whereas an intermediate power of 370 W produces improved metallurgical bonding and the highest hardness value. The topic is practically relevant for titanium alloy surface engineering and aerospace applications, and the revised manuscript shows improvement in formatting, terminology consistency, figure presentation, and experimental description. The authors have also addressed several reviewer comments related to abstract clarity, figure labeling, statistical presentation of hardness values, and manuscript organization. However, despite these improvements, several important scientific concerns remain insufficiently addressed. The overall novelty of the work remains limited because the observed dependence of coating quality on laser energy density largely confirms already established SLM behavior. In addition, the distinction between the AlMgSc feedstock and the TiAl intermetallic reaction zone is still not fully clarified throughout the manuscript. The mechanistic discussion continues to rely heavily on qualitative Gibbs free energy arguments without quantitative thermodynamic calculations or CALPHAD analysis, making several conclusions speculative. Furthermore, the study only evaluates hardness and microstructure, while no adhesion, wear, oxidation, or corrosion testing is provided to support the claimed protective performance of the coatings. The statistical rigor is also still relatively weak, with limited discussion of repeatability and uncertainty. Therefore, although the manuscript has improved after revision and may be suitable for publication after further revision, several major scientific issues should still be addressed before acceptance.

Recommendation: Major Revision

Major comments:

1. The novelty and scientific contribution of the work should be more clearly articulated. The observed trend of insufficient energy input causing poor bonding and excessive energy causing cracking is already well established in the SLM literature. The authors should explicitly explain what new insight this study contributes beyond parameter optimization.

2. The manuscript still contains ambiguity regarding the material system. The feedstock material is AlMgSc powder, while the manuscript repeatedly refers to the product as a “TiAl coating.” The authors should clearly distinguish the deposited AlMgSc layer, the Ti-Al interfacial reaction zone, and the intermetallic transition region throughout the manuscript.

3. The mechanistic discussion remains largely qualitative. The repeated use of Gibbs free energy arguments without quantitative thermodynamic calculations, phase diagram analysis, or CALPHAD support weakens the scientific rigor of the discussion. At minimum, the speculative nature of these interpretations should be explicitly acknowledged and moderated.

4. The manuscript claims protective coating functionality for aerospace applications, yet no wear resistance, oxidation resistance, corrosion resistance, or adhesion testing is presented. Hardness alone is insufficient to demonstrate coating performance. The engineering claims should therefore be moderated unless additional functional testing is included.

5. The statistical rigor should be improved further. The manuscript now includes standard deviation values for hardness measurements, which is appreciated; however, the number of independently fabricated samples per condition remains unclear. The authors should clarify the repeatability of the experiments and provide statistical treatment for coating thickness measurements as well.

6. The literature review should be revised to focus more specifically on TiAl intermetallic coatings on titanium substrates and related interfacial reaction systems. Many currently cited references are generic SLM studies with limited direct relevance to the present material system.

Minor comments:

1. The manuscript still contains several long and grammatically awkward sentences, particularly in Sections 3.1 and 3.2. Additional English editing is recommended.

2. Figure quality has improved, but several SEM images still require clearer contrast and labeling for publication quality.

3. The discussion of the non-monotonic coating thickness trend should be strengthened further with a more detailed explanation of melt pool dynamics and possible evaporation or recoil pressure effects.

4. The terminology describing the coating should be made fully consistent throughout the manuscript.

**********

what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: Yes: Ahmed H. Maamoun

Reviewer #2: No

Reviewer #4: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

To ensure your figures meet our technical requirements, please review our figure guidelines: https://journals.plos.org/plosone/s/figures

You may also use PLOS’s free figure tool, NAAS, to help you prepare publication quality figures: https://journals.plos.org/plosone/s/figures#loc-tools-for-figure-preparation.

NAAS will assess whether your figures meet our technical requirements by comparing each figure against our figure specifications.

Dear Dr. Yong,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Aug 21 2026 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

• A letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

As the corresponding author, your ORCID iD is verified in the submission system and will appear in the published article. PLOS supports the use of ORCID, and we encourage all coauthors to register for an ORCID iD and use it as well. Please encourage your coauthors to verify their ORCID iD within the submission system before final acceptance, as unverified ORCID iDs will not appear in the published article. Only  the individual author can complete the verification step; PLOS staff cannot  verify ORCID iDs on behalf of authors.

We look forward to receiving your revised manuscript.

Kind regards,

Hari Murthy, Ph.D.

Academic Editor

PLOS One

Journal Requirements:

1. If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

2. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #4: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #4: Yes

**********

Reviewer #1: The revised manuscript is significantly improved. The review comments and recommendations have been addressed. However, some issues still need to be considered as follows:

- In Section 2, the powder material name should be clearly stated before presenting the powder characteristics such as particle size distribution. Also, it is very crucial to illustrate the powder morphology and particle shape.

- In subsection 3.2 related to phase analysis; the manuscript text should illustrate more analysis and discussion for the data presented in Table 3 related to the significant variation of elements' wt% of the EDS results throughout the manuscript text, and the discussion should be supported by relevant references.

- The directions related to the building direction should be labelled on all Figures containing SEM and microscopic images.

- The references of the presented data in Figure 4 should be cited and illustrated in a separate column in the Table.

Reviewer #2:  (No Response)

Reviewer #4: The revised manuscript presents a systematic experimental investigation of the effect of laser power on the microstructure, phase evolution, elemental distribution, and microhardness of selective laser melting (SLM) coatings deposited on TC4 titanium alloy. The experimental design is straightforward, and the combination of SEM, EDS, XRD, and hardness measurements provides a comprehensive characterization of the coatings. The manuscript is generally well organized, and the experimental results consistently demonstrate that a laser power of 370 W produces the most favorable coating quality with improved metallurgical bonding and the highest microhardness.

The current version has been substantially improved in terms of experimental description, statistical information, and presentation of the results. The distinction between the deposited layer and the interfacial reaction zone is much clearer, the experimental repeatability is better documented, and the discussion has been strengthened with additional analysis of coating thickness evolution and microstructural development. Overall, the study is technically sound and provides useful experimental data for understanding the influence of laser power on this specific coating system.

I only have a few minor comments that should be addressed before publication.

The English writing has improved, but the manuscript would still benefit from careful language editing. Several sentences remain grammatically awkward or unnecessarily long, particularly in the Introduction and Discussion sections. A final proofreading by a fluent English speaker is recommended to improve readability.

The manuscript occasionally overstates the significance of its findings. Expressions such as "fills the existing research gap," "forms a new understanding," and "provides theoretical support" should be moderated. The work represents a systematic experimental study of laser power optimization for a particular material system, and the conclusions should reflect this scope more appropriately.

Some mechanistic explanations remain largely qualitative. Discussions involving Gibbs free energy, recoil pressure, keyhole transition, and phase evolution are reasonable interpretations but are not supported by quantitative thermodynamic calculations or numerical simulations. The corresponding statements should therefore be presented as proposed mechanisms rather than definitive conclusions.

Although the terminology has been improved, some inconsistency remains in the description of the coating. Terms such as "TiAl coating," "composite coating," and "protective coating" are still used interchangeably in several sections. Using consistent terminology throughout the manuscript would improve clarity.

Finally, several minor typographical and formatting issues remain, including duplicated words in the Abstract, occasional spacing inconsistencies, and minor formatting problems for units and symbols. These should be corrected during the final proofreading stage.

Overall, the manuscript is technically sound, the experimental methodology is appropriate, and the conclusions are generally supported by the presented results. The remaining issues are minor editorial revisions that do not require additional experiments. Therefore, I recommend **acceptance after minor revision**.

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Reviewer #1: Yes: Ahmed H. Maamoun

Reviewer #2: No

Reviewer #4: No

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Effect of Laser Power Variation on Microstructure and Properties of Selective Laser Melting Coatings Deposited on TC4 Titanium Alloy

PONE-D-26-09790R3

Dear Dr. Yong,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Academic Editor

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Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: All comments have been addressed

Reviewer #4: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions??>

Reviewer #1: Yes

Reviewer #4: Yes

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3. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #4: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #4: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #4: Yes

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Reviewer #1: The review comments and recommendations have been addressed. As a minor comment, the future perspective should be added to the conclusion.

Reviewer #4: All issues have been addressed properly by the authors, I would like to recommend accept this manuscript in current form.

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what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review?  For information about this choice, including consent withdrawal, please see our Privacy Policy

Reviewer #1: Yes: Ahmed H. Maamoun

Reviewer #4: No

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