Microstructural Evaluation and Tensile Properties of Al-Mg-Sc-Zr Alloys Prepared by LPBF

Round 1

Reviewer 1 Report (New Reviewer)

This paper describes the manufacture and analysis of an additively produced Al-Mg-Sc alloy. The alloy itself it very similar (within the range) of commercial Scalmalloy, for which there have been a lot of published AM papers. Whilst the paper does present some new results, these show the same features as in the previously published work. Previous work has also done a more thorough job in explaining the microstructures seen in Scalmalloy AM builds. Much of the discussion is rather speculative with little direct evidence for the points claimed. Furthermore, the paper is hampered by simple errors such as numerous missing references, suggesting it was not carefully checked. Unfortunately, this undermines confidence in the rest of the work, which is itself has a low level of novelty.

There are some significant errors in English that inhibit understanding, and it would be good to have the manuscript carefully checked by a strong English writer.

Author Response

Reviewer 1:

Comment 1: This paper describes the manufacture and analysis of an additively produced Al-Mg-Sc alloy. The alloy itself it very similar (within the range) of commercial Scalmalloy, for which there have been a lot of published AM papers. Whilst the paper does present some new results, these show the same features as in the previously published work. Previous work has also done a more thorough job in explaining the microstructures seen in Scalmalloy AM builds. Much of the discussion is rather speculative with little direct evidence for the points claimed. Furthermore, the paper is hampered by simple errors such as numerous missing references, suggesting it was not carefully checked. Unfortunately, this undermines confidence in the rest of the work, which is itself has a low level of novelty.

Response 1: Thank you for the valuable advice. The Al-Mg-Sc-Zr alloy is one of the commonly used high-strength aluminum alloys for additive manufacturing, but its high price limits its application. Currently, there are two processes that significantly increase the cost in the production of Al-Mg-Sc-Zr alloy: one is the large amount of Sc addition, and the other is the use of large gas atomization equipment (in order to obtain spheroidal powder of suitable size). In this study, we used a small laboratory equipment to prepare the finest Al-Mg-Sc-Zr powder reported in public and appropriately reduced the Sc content, which significantly reduced the cost of the powder production process. However, the poor fluidity of the ultrafine powder can lead to defects such as pores, and we improved the sample density through scanning strategies and parameter optimization. Then, to address the high-solid-solution structure under ultra-high cooling speed, we used a direct short-time aging method to improve the preparation efficiency and finally obtained a sample with performance close to that of more expensive powders. Obtaining fine powder through screening in the industrial field is usually relatively cheap, so the results obtained in this study can provide guidance for low-cost additive manufacturing and fully utilizing powders of different sizes. We apologize for the draft formatting errors and the loss of reference information during the conversion of the template. We have checked the document on different computers and all errors have been corrected (Page 5, Line 167; Page 9, Line 274; Page 10, Lines 304 and 307), as well as the grammar mistakes (Page 1, lines 13-14 and 19, etc., highlighted in the article).

Comment 2: Comments on the Quality of English Language

There are some significant errors in English that inhibit understanding, and it would be good to have the manuscript carefully checked by a strong English writer.

Response 2: Thank you for your valuable and thoughtful comments. We have carefully checked and improved the English writing in this article. (Page 1, lines 13-14 and 19, etc., highlighted in the article). 

Author Response File: Author Response.docx

Reviewer 2 Report (New Reviewer)

The manuscript is devoted to a study of the microstructure and mechanical properties of an Al-Mg alloy modified with Zr/Sc and obtained by laser powder bed fusion (LPBF). The authors studied in detail the microstructure parameters of the samples, as well as the effect of heat treatment on the hardness of the alloy. Moreover, the authors compared the microstructure and properties of the sample obtained by laser powder bed fusion and traditional casting. The manuscript is well written, contains significant results, and the conclusions are supported by the results obtained.

I have the following comments on the manuscript:

Fig. 5a. The IPF legend indices are completely invisible.

Fig. 7a. The IPF legend indices are completely invisible. Also, the caption (a) is missing from figure (a).

Line 327. 3.4. “Mechanical propertie”. Must be “Mechanical properties”.

Table 3. The accuracy of the elongation value and the accuracy of the error should be the same. For example, 14.8±0.8 %.

Line 251. “Error! Reference source not found.” Correction is necessary. Also further down the text contains this typo. Authors should correct the text.

Lines 342-343. “Third, according to the kernel average misorientation (KAM) maps (Fig. 10), a high density of misorientation was observed at the grain boundaries of as-printed sample...” Since the authors are talking about grain boundaries here, I think it would be better to add grain boundaries to the KAM maps.

Fig. 10. KAM maps. A legend for the value of the local misorientation distribution must be added to the maps. Moreover, in this case it will be better to identify the average value of the KAM angle.

Line 369. A dot is missing at the end of the sentence.

Line 393. A dot is missing at the end of the sentence. “…14.8±0.76 % respectively.” The accuracy of the elongation value and the accuracy of the error should be the same: 14.8±0.8 %.

Author Response

Reviewer 2: The manuscript is devoted to a study of the microstructure and mechanical properties of an Al-Mg alloy modified with Zr/Sc and obtained by laser powder bed fusion (LPBF). The authors studied in detail the microstructure parameters of the samples, as well as the effect of heat treatment on the hardness of the alloy. Moreover, the authors compared the microstructure and properties of the sample obtained by laser powder bed fusion and traditional casting. The manuscript is well written, contains significant results, and the conclusions are supported by the results obtained.

Comment 1: Fig. 5a. The IPF legend indices are completely invisible.

Response 1: Thank you for pointing out our oversight. In the resubmitted manuscript we have updated the IPF diagrams in Figures 6, 7 and 8 (Page 7-8).

Comment 2: Fig. 7a. The IPF legend indices are completely invisible. Also, the caption (a) is missing from figure (a).

Response 2: In the resubmitted manuscript we have updated the IPF diagrams in Figures 6, 7 and 8 (Page 7-8). We modified Figure 8 and enlarged the caption of (a).

Comment 3: Line 327. 3.4. “Mechanical propertie”. Must be “Mechanical properties”.

Response 3: Thank you very much for your kindly reminding. We have modified and replaced “Mechanical propertie” in line 327 with “Mechanical properties”. (Page 8, Line 255)

Comment 4: Table 3. The accuracy of the elongation value and the accuracy of the error should be the same. For example, 14.8±0.8 %.

Response 4: Thank you for pointing out our oversight. In the revised manuscript we have harmonized the accuracy of the elongation values and the accuracy of the errors. (Page 12, Table 4)

Comment 5: Line 251. “Error! Reference source not found.” Correction is necessary. Also further down the text contains this typo. Authors should correct the text.

Response 5: Thank you for pointing out our oversight. We apologize for the draft formatting errors and the loss of reference information during the conversion of the template. We have checked the document on different computers and all errors have been corrected, as well as the grammar mistakes (Page 5, Line 167; Page 9, Line 274; Page 10, Lines 304 and 307).

Comment 6: Lines 342-343. “Third, according to the kernel average misorientation (KAM) maps (Fig. 10), a high density of misorientation was observed at the grain boundaries of as-printed sample...” Since the authors are talking about grain boundaries here, I think it would be better to add grain boundaries to the KAM maps.

Response 6: Thank you for your comment and suggestion. In the new manuscript, the KAM maps with grain boundaries have been added. (Page 12, Fig 11c and d)

Comment 7: Fig. 10. KAM maps. A legend for the value of the local misorientation distribution must be added to the maps. Moreover, in this case it will be better to identify the average value of the KAM angle.

Response 7: Thank you very much for your valuable comment and advice. We have added the local misorientation distribution maps and given the average value of KAM angle. (Page 12, Fig 11c and d (insert))

Comment 8: Line 369. A dot is missing at the end of the sentence.

Response 8: Thank you for pointing out our oversight. We have added the full stop in the relevant sentence. (Page 12, Line 388)

Comment 9: Line 393. A dot is missing at the end of the sentence. “…14.8±0.76 % respectively.” The accuracy of the elongation value and the accuracy of the error should be the same: 14.8±0.8 %.

Response 9: Thank you for pointing out our oversight. In the revised manuscript, we have added the full stop in the relevant sentence. Also changed from "14.8 ± 0.76 %" to "14.8 ± 0.8 %". (Page 13, Line 414)

Author Response File: Author Response.docx

Reviewer 3 Report (New Reviewer)

Dear Authors,

the paper contains interesting results, but take care about editing and there are still several errors in the text. Please take car ebefore resubmitting next time.

Several detailed comments.

Line 133: It  is suggested to add a table with the details of the heat treatments in order to better correlate the results with the treatments.

Line 142: There are methods (“intercept methods” is one well known and accepted) for the determination of the mean-grain size. The counts proposed on 200 grains is interesting and probably even more precise, but not covered by International  Standard, i.e. ASTM E122, please repeat the measurements.

Line 159: there is an error remark on the line

Caption of Figure 3: Optical Microscope images not “OM micrographs”

Line 251: there is an error remark on the line

Line 282 and 285: there is an error remark on the line

General Comments:

How many test specimens for condition? Please add in the caption of Table 3 the  fact that the values are mean values and add the number of tested specimens for each condition.

I am not a mother tongue , but the English, especially in the abstract, requires a review. 

Author Response

Reviewer 3: the paper contains interesting results, but take care about editing and there are still several errors in the text. Please take car ebefore resubmitting next time.

Comment 1: Line 133: It is suggested to add a table with the details of the heat treatments in order to better correlate the results with the treatments.

Response 1: Thank you very much for your valuable comment and advice. Based on the reviewer's comment, we have added a table about heat treatment parameters. (Page 4, Table 2)

Comment 2: Line 142: There are methods (“intercept methods” is one well known and accepted) for the determination of the mean-grain size. The counts proposed on 200 grains is interesting and probably even more precise, but not covered by International Standard, i.e. ASTM E122, please repeat the measurements.

Response 2: Thank you very much for your valuable comment suggestion. The grain size has been remeasured according to ASTM E122. (Page 4, Lines 148-149; Page 6-7, Lines 210, 212, 223-225, 232)

Comment 3: Line 159: there is an error remark on the line.

Response 3: Thank you for pointing out our oversight. The relevant errors have been revised in the new manuscript. (Page 5, Line 167)

Comment 4: Caption of Figure 3: Optical Microscope images not “OM micrographs”.

Response 4: Thank you for pointing out our oversight. In the revised manuscript, we have modified the caption of Fig. 3 by changing "OM micrographs" to "Optical Microscope images". (Page 5, Line 180)

Comment 5: Line 251: there is an error remark on the line.

Response 5: Thank you for pointing out our oversight. The relevant errors have been revised in the new manuscript. (Page 9, Line 274)

Comment 6: Line 282 and 285: there is an error remark on the line.

Response 6: Thank you for pointing out our oversight. The relevant errors have been revised in the new manuscript. (Page 10, Lines 304 and307)

Comment 7: How many test specimens for condition? Please add in the caption of Table 3 the fact that the values are mean values and add the number of tested specimens for each condition.

Response 7: Thank you very much for your valuable comment and kindly reminding. Three samples were tested for each condition and the mean and standard deviation were calculated. The relevant contents have been added to the caption of Table 4 in the revised manuscript. (Page 9, Lines 269-271)

Comment 8: Comments on the Quality of English Language

I am not a mother tongue, but the English, especially in the abstract, requires a review.

Response 8: Thank you for your valuable and thoughtful comments. We have carefully checked and improved the English writing in the revised manuscript. (Page 1, lines 13-14 and 19, etc., highlighted in the article).

Author Response File: Author Response.docx

Reviewer 4 Report (New Reviewer)

The present work deals with the microstructural and corrosion properties of LPBF samples in aluminium alloy. The work is very interesting and well written and the results properly explained. Considering this I can suggest publication for this work after the following major revisions

-Please improve the introduction section adding recent works that discuss several properties of LPBF samples such as https://doi.org/10.1038/s41598-022-18176-x

-Please describe how the parameters for the printing were selected

-Please check the manuscript because in some places is written “Error! Reference source not found”

-TEM and EBSD measurements are extremely interesting but the discussion of the results should be improved also on the base of the current literature. Moreover, also performing “normal” SEM investigation together with these analyses can remarkably improve the quality of the paper

-Considering the mechanical properties I suggest to add also micro-hardness tests and compare the results with the tensile tests

Author Response

Reviewer 4: The present work deals with the microstructural and corrosion properties of LPBF samples in aluminium alloy. The work is very interesting and well written and the results properly explained. Considering this I can suggest publication for this work after the following major revisions.

Comment 1: Please improve the introduction section adding recent works that discuss several properties of LPBF samples such as https://doi.org/10.1038/s41598-022-18176-x.

Response 1: Thank you very much for your valuable comment and advice. We have modified the Introduction parts. In the revised manuscript, more relevant literatures including the recommended articles have been cited to show and discuss better the novelties of this work. (Page 2, Lines 48-53 and Ref. [14], [15).

Comment 2: Please describe how the parameters for the printing were selected.

Response 2: Thank you very much for your comment and question. In this work, the initial selection of LPBF parameters was determined by the density measured by the standard Archimedes drainage method and then combined with metallographic observations to screen for the optimal processing parameters. (Page 3-4, Lines 130-132)

Comment 3: Please check the manuscript because in some places is written “Error! Reference source not found”.

Response 3: We apologize for the draft formatting errors and the loss of reference information during the conversion of the template. We have checked the document on different computers and all errors have been corrected, as well as the grammar mistakes. (Page 5, Line 167; Page 9, Line 274; Page 10, Lines 304 and 307).

Comment 4: TEM and EBSD measurements are extremely interesting but the discussion of the results should be improved also on the base of the current literature. Moreover, also performing “normal” SEM investigation together with these analyses can remarkably improve the quality of the paper.

Response 4: Thank you for your comment and suggestion. In the revised manuscript we have added SEM analysis to further analyze the microstructure evolution and element distribution. (Page 7-8, Fig. 5, Fig. 7a, Lines 201-204, 214-215, 225)

Comment 5: Considering the mechanical properties I suggest to add also micro-hardness tests and compare the results with the tensile tests.

Response 5: Thank you very much for your valuable comment and advice. As you pointed out, we have added the microhardness data in the revised manuscript and modified the content of subsection 3.4. (Page 8-9, Lines 256-265, Fig. 9a and Table 4)

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report (New Reviewer)

Revised paper significantly improved

Check English again - most errors corrected though

Author Response

Reviewer 1: Revised paper significantly improved.

Comment: Comments on the Quality of English Language: Check English again - most errors corrected though.

Response: Thank you very much for your valuable comment and kindly reminding. We have carefully checked and improved the English writing in this article. (Page 2, lines 82-83 and 89, etc. Highlighted marks in the article).

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

The authors significantly revised and improved the manuscript. Nevertheless, I still have a few comments on the manuscript to be corrected by the authors:

1. Fig. 5-8. The figure indexes remain invisible.

2. Table 4. With what accuracy was the hardness measured? The accuracy of the standard deviation is very high.

3. Fig. 11. The authors added a misorientation histogram. But it is also necessary to identify the colors on the KAM. The color distribution legend is also better added to the figure.

Author Response

Reviewer 2: The authors significantly revised and improved the manuscript. Nevertheless, I still have a few comments on the manuscript to be corrected by the authors:

Comment 1: Fig. 5-8. The figure indexes remain invisible.

Response 1: Thank you very much for your kindly reminding. In the resubmitted manuscript we have updated Figures 5-8. (Page 7, Fig. 5 and 6, Page 8, Fig. 7 and 8).

Comment 2: Table 4. With what accuracy was the hardness measured? The accuracy of the standard deviation is very high.

Response 2: Thank you very much for your comment and question. This material exhibits inhomogeneity of microstructure, therefore resulting in inhomogeneity of hardness. To ensure the authenticity of the data. We randomly selected the test position during the microhardness measurement. Some positions corresponded to the ultrafine equiaxed grain zone at the molten pool boundary, which has relatively high microhardness, while the coarse grain zone in the center of the molten pool has a lower microhardness value, as shown in the pdf file below. The hardness value was calculated from the indentation area.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

ok accepted

Author Response

Comments and Suggestions for Authors:
ok accepted.

Response: Thank you very much for your careful review of our articles.

Reviewer 4 Report (New Reviewer)

The paper Is now suitable for publication

Author Response

Comments and Suggestions for Authors
The paper Is now suitable for publication.

Response: Thank you very much for your careful review of our articles.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The authors have conducted an interesting comparison of the microstructure and of the tensile properties of one Al-Mg-Sc-Zr-alloy manufactured by means of casting and by means of LPBF. The presented results are worth to be published. However, the manuscript leaves room for improvements at several points.

·         Title:

o   The title of the manuscript is misleading. No effects of processing parameters or scanning strategies on the resulting microstructure are shown. They were not investigated, as specimens manufactured by the “optimised” set of processing parameters only were analysed with respect to the microstructure. I would recommend going into this direction: “Comparison of the microstructure and of the tensile properties of one Al-Mg-Sc-Zr-alloy manufactured by means of casting and by means of LPBF”

·         Introduction:

o   A few more examples of successful LPBF processing of Sc/Zr-modified Al-alloys should be presented from literature.

o   As the occurrence of the bimodal microstructure was not made for the first time, some other studies should be referenced, which also observe this kind of microstructure for Al-Sc-alloys or Al-Fe-Ni-alloys…

o   Solubility values should not be mentioned without referencing (line 56 ff.)

·         Materials and sample preparation:

o   There is some missing information regarding the experimental conditions, which should be added:

§  Layer thickness

§  Laser spot size

§  inter layer time

§  Geometry of optimisation samples

§  Was there any contour scanning used?

o   It is not clear from Fig 3 how many specimens were cut out of the block and at which locations.

o   Characterisation methods:

§  Please check wording of EBSD

§  Please specify the conditions of the characterisation tools (e.g., step size and size of measured area for EBSD and so on)

·         Results:

o   The authors have decided to have separated sections for Results and Discussions, which is a good choice. However, they should be careful to not discuss results in the results section (e.g. line 114 f. is discussion and not just a presentation of results)

o   Table 2: The density measurements were conducted by OM. This is a relative measurement. I would suggest to rather present the relative measurement results than the calculated absolute density results. The basis for the absolute results is not given in the manuscript. Three digits after the decimal point seems to be quite ambitious. Could the authors please comment on the measurement uncertainty?

o   Fig 7: Interesting but bad quality (resolution). Scale bar of 7b is not readable. What does the orange frame stands for?

·         Discussion:

o   Huge bits of the interesting discussion of the microstructure are based on finding of reference 41. It would be good to see a brief summary, what exactly did the authors of reference 41. In addition, where are the differences to the presented work? Where does the very specific cooling rates come from? This is not clear to the reader.

o   Cooling rates: The authors should check all cooling rates. They present them consistently as e.g. 106 K/s instead of 10^6 K/s.

·         Conclusions:

o   The first sentence is misleading. There was no alloy development involved in the presented work.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear author, dear editor,

In this work, the PBF processing of an Al-Mg-Sc-Zr is considered. From my point of view, the novelty content is low since it is a commercial alloy (Scalmalloy) that has been examined in many other works. Thus, this alloy is listed in the product portfolio of many AM manufacturers. The mechanical properties are specified in the manufacturer's datasheets with yield point = 480-500 MPa, and tensile strength = 510-530 MPa and are above the values ​​measured here. This is because it is a material that has to be post-heat treated, which was not done in this work. This also explains the insufficient properties of the cast alloy (there was no heat treatment). However, the states of the cast reference state that were examined are not described in the test procedure, so this is an assumption. I also make the following comments:

- I recommend revising the manuscript linguistically and reading the grammar and especially the correct choice of words by a native speaker. In any case, I (not a native speaker) felt the wrong words were used in several places, and the grammar wasn't applied correctly.

- The contrast in picture 1 should be adjusted. The picture is very dark

- Why is such a high proportion of fines in the powder used (see Figure 1b)? Conventionally, particles smaller than 10-15 µm are removed by classification to create a good, homogeneous powder bed because of the good powders' flowability.

- How and where was the powder produced?

- Because Al is an element with a high affinity for O, the O content should be provided in Table 1 because oxides' formation significantly influences the laser coupling.

- Which parameters were used for the XRD measurement (angle, current, anode, software….); Please write the test procedure in such a manner that a third party can repeat the results without consultation.

- The size information in picture 3 is very small. I recommend enlarging it for readability.

- The results are partly discussed in the results section. If there is a clear separation between the results section and the discussion (as here), then there should be no discussion of the results in the results section, as this leads to redundancies and an unnecessary length of the manuscript. As an example, I would like to mention the discussion about the presence of the pores and the undetected phase Al3(Sc, Zr) in the case of the PBF-processed samples.

- Surely, an overview recording of the samples makes sense. Nevertheless, the microstructure recordings in Figure 4 are so low in contrast and have an insufficient resolution for Figures d), e), f), and 5 b). The Al3(Sc,Zr) phase cannot be seen in Figure 5b either.

- The mean grain size is mentioned later. In the course of the experiment, it should be stated how these values ​​(quantitative image analysis, EBSD, software?) were determined.

- The EBSD recordings are of very good quality. A quantitative classification of the results in the form of a simple color bar would be desirable for the EDS results.

- The higher mechanical properties of the samples, constructed using the meander scan strategy, are lower than with the stripe scan strategy. The reason given is the higher defect density. This is true for 3 out of 5 parameters. For the samples generated with a laser power of 250 W, the values ​​of the sample that was constructed using the meander scan strategy are missing. In addition, the density (I refer to this since no defect density in the form of crack density or porosity is mentioned) of both samples at a laser power of 220 W is on the same level, so the argument given cannot be understood. Here I recommend adding the defects in the form of porosity and crack density in Table 2. It also makes no sense to list all the parameters here if they are not discussed later. Here it is advisable to use the sample that has the best structure.

- What is the condition of the cast reference sample? Was there a heat treatment here?

- The microstructure formation process is presented in the discussion below. General knowledge from other works is mentioned here. Our results are insufficient to explain the structure formation process during solidification and reheating through the alternating heat input (here, solidification simulations using the Scheil-Gulliver approach are necessary or refer to such a work).

- The following discussion of the higher strength of the PBF-processed samples compared to the cast reference sample also reflects known knowledge.

Summary: Unfortunately, I cannot recommend the manuscript for publication. I cite the insufficient test execution, the discussion of the results in the results section, the low level of novelty, and the lack of scientific questions as reasons. Furthermore, it is a well-studied material that has already been investigated in many other works and can currently also be purchased from many AM manufacturers as a powder with appropriate exposure parameters.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have partially improved their manuscript according to my previous comments. However, they left space for further improvement. A revision is necesssary prior to publication.

The following points should be addressed:

·       The authors have added a brief overview over other work related to Sc/Zr-modified Al-alloys in the context of PBF-LB/M. However, a distinction to their own work was not made. It should come clear from the introduction, what is the novelty of the study, what is the distinction to other work.

·        The authors added the following sentence to the introduction: “In this work, we have tried to reduce the powder cost by appropriately reducing the Sc content and using small atomization equipment to prepare fine powders”. No word is said on this in the experimental part. Did they produce their own powder? If yes, this should be described in more detail. If not, the supplier should be mentioned and an explanation on “using small atomization equipment to prepare fine powders” should be given. In addition, an explanation on the supposed reduction of the Sc condition should be given. Here it might be worth to give a comparison of the chemical composition of the material used in the current study to the composition of materials of other cited work and to the specification of the commercial alloy Scalmalloy.

·        The authors added the following sentence: “Due to the rapid 37 cooling rate, the large temperature gradient, and the heterogeneous temperature field in 38 the melt pool, the LPBF-prepared alloy usually achieves a bimodal microstructure with 39 excellent properties [4-7]“ This statement is not generally applicable to all PBF-LB/M alloys, but only to specific alloys such as the family of Sc/Zr modified aluminium alloys.

·        I have asked the authors for information about inter layer time and contour scanning. They gave the response in the response letter, but  the information is still missing in the manuscript. I do not have a personal interest in this information. These information are important to the readers of the manuscript to enhance comparability.

·        Information on how many specimens were cut out of  the blocks and where can be improved. “At least 3” is not sufficient.

Reviewer 2 Report

Dear Editor,

Some points have still not been adjusted. The references are inconsistent, and the additional requested investigations are also missing (where is the novelty?). From my point of view, it makes no sense to consider a precipitation-hardenable material in the cast condition as a reference. In the case of PBF processing (high solution state), there is a recurring heat input. In addition to a high dislocation density, a small number of precipitations can also be expected. In addition, the results are still interpreted in the results part. Images are still lacking in contrast and meaningless in places (e.g., image 5; non-quantitative representation of the EDS results in 7 and 8). Furthermore, the manuscript can always be improved linguistically. Finally, I would like to point out again that this is a well-studied material, so the results obtained have little novelty content. Here the authors should explicitly state which results about the state of knowledge were obtained with this paper.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

Dear editor,

I am now reading the manuscript for the third time and will reject it again because the reviewers did not respond to my primary criticism. In any case, my questions are answered without reference to them. Nevertheless, the authors have revised some things but have not cleaned up the critical points.

A well-studied and commercially available material is processed using PBF, and its properties are compared to a cast reference state. Finally, it is stated that the material in the PBF condition has better properties than the cast reference material. For the third time, I say this procedure makes no sense since it is a case of a precipitation-hardenable material, which must also be examined in the corresponding condition. Thus, additional investigations are missing, so I reject the paper (besides the low novelty content) again. Marginal changes are always made. In addition, nine authors are named, some of whom have no contribution. From my point of view, only authors who contributed to the writing should be named (requiring funding is not sufficient). Anything else is bad scientific practice and should be reprimanded.

How the journal carries out a peer review is also criticized. It must not be the case that I receive the manuscript again after being recommended "Rejection" twice and have to make a statement within three days of whether it can be published. Here I seriously ask myself what the primary interest of the journal is.