Phase Diagram of Binary Alloy Nanoparticles under High Pressure
Round 1
Reviewer 1 Report
General:
In this manuscript, the authors examined the effects of size and pressure on the shape of the phase diagram of nanoparticles by using the CALPHAD method for general A-B alloy systems based on a regular solution model. The novelty lies that the thermodynamic models which account for the size (surface) effect and the pressure effects were combined in a consistent simplified regular solution model, which could be useful for CALPHAD practitioners. Therefore, this manuscript is recommended for publication in the journal materials. Several minor issues still need to be addressed before publication (see below).
Major
None
Minor
- There were extensive discussions on the theory and models used in the present study. However, there is no description on how this model is implemented. By looking at the figures, the review presumes the model is implemented in the FactSage software. At least one or two sentences are needed in the paper to describe the model implementation.
- It would be nice if this model is applied to some real systems where there exists enough experimental data at high pressure for nanoparticles. However, I presume that is not the focus of this manuscript.
Typo and Grammar
- In the Abstract: “ALPHAD” --> “CALPHAD”
- Line 98: ignorable --> negligible
Author Response
Dear Reviewer 1,
Thank you very much for the kind comments from reviewers. We have incorporated the suggested issues by the reviewers as follows.
Response to Reviewer 1 Comments
Point 1: There were extensive discussions on the theory and models used in the present study. However, there is no description on how this model is implemented. By looking at the figures, the review presumes the model is implemented in the FactSage software. At least one or two sentences are needed in the paper to describe the model implementation.
Response: A new sentence was included in line 219.
Point 2: It would be nice if this model is applied to some real systems where there exists enough experimental data at high pressure for nanoparticles. However, I presume that is not the focus of this manuscript.
Response: The purpose of this study is to suggest the calculation methodology of phase diagrams considering the size and pressure effects. Practical applications will be the topics of our future studies. Thank you for your understanding.
Point 3:
In the Abstract: “ALPHAD” --> “CALPHAD”
Line 98: ignorable --> negligible
Response: Typos were corrected.
We believe that the revised manuscript is acceptable and published soon in Materials.
Sincerely,
Han-Gyeol Kim and Joonho Lee
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In the manuscript, the authors report on derivations of eutectic phase diagrams under the influence of pressure and surface tension of nanoparticles using a CALPHAD description based on regular solution models. The manuscript has a number of serious flaws. See below an incomplete list of distraction points. I recommend the rejection of the manuscript.- The authors do not properly cite their own previous work. Especially, the citation [56-61] in line 40 is completely inappropriate in the present form. Non of these articles, each authored and co-authored by at least one of the three authors of the present manuscript, is mentioned elsewhere in the manuscript.
- The model description is incomplete. For instance, following Eq. (26), it seams as if the excess volume is hidden somehow in the interaction parameter from the regular solution model. However, Fig. 4 tells that this parameter has been varied independently from interaction parameters.
- It is not clearly discussed how the presented modeling results relate to experimental findings.
- It is not explained how (by which method) the phase diagrams are calculated from the Gibbs-free energy curves.
- The results are not at all sufficiently discussed.
- ...
Author Response
Dear Reviewer 2,
Thank you very much for the kind comments from reviewers. We have incorporated the suggested issues by the reviewers as follows.
Response to Reviewer 2 Comments
Point 1: The authors do not properly cite their own previous work. Especially, the citation [56-61] in line 40 is completely inappropriate in the present form. Non of these articles, each authored and co-authored by at least one of the three authors of the present manuscript, is mentioned elsewhere in the manuscript.
Response: These articles (Refs. 56-61) were mentioned in line 180 also. These articles reported the calculation results of the pressure diagrams of various systems. Especially, in Refs. 59 and 60, the relation between the excess volume and the interaction parameter was reported in detail.
Point 2: The model description is incomplete. For instance, following Eq. (26), it seams as if the excess volume is hidden somehow in the interaction parameter from the regular solution model. However, Fig. 4 tells that this parameter has been varied independently from interaction parameters.
Response: The equation (24) (old number 25) has been extended to show the relation between the excess volume and the interaction parameter.
Point 3: It is not clearly discussed how the presented modeling results relate to experimental findings.
Response: The purpose of the present study is to provide a general principle on the direction of changes in phase stability of nanoparticles under pressure, which is first suggested in this paper. Applications to experimental results will be our future research topics.
Point 4: It is not explained how (by which method) the phase diagrams are calculated from the Gibbs-free energy curves.
Response: The phase diagrams were calculated by Gibbs-free energy minimization with FactSage program. A new sentence was added in line 219.
Point 5: The results are not at all sufficiently discussed.
Response: Additional discussion was included in line 288.
We believe that the revised manuscript is acceptable and published soon in Materials.
Sincerely,
Han-Gyeol Kim and Joonho Lee
Author Response File: Author Response.pdf
Reviewer 3 Report
In the present work, the effect of particle size and pressure on the phase diagram of nanoparticles is investigated using CALPHAAD method for a binary system. For this purpose, a regular solution model (for both liquid and solid solution) is applied. In particular, the change in the eutectic point was observed varying the interaction parameters of both the solid and the liquid solution. A similar thermodynamic approach has been used in a number of previous studies, some of which have been duly cited. What is new in this study can be defined as: (i) it was found that at negative deviations from the ideal solution for the liquid phase (∆Hsol <0) the eutectic temperature decreases during the transition from bulk phase to nanoparticles. The same effect was detected with increasing of pressure. The position of the eutecticum in relation to the composition also changes. (ii) For the liquid phase interaction parameter equal to zero, the eutectic temperature decreases during the transition from bulk to nanophase. Depending on the excess volume of the liquid (negative or positive) eutectic T also changes.
In conclusion, I have no significant remarks on the work, except to check once again for typos (they occur here and there).
Author Response
Dear Reviewer 3,
Thank you very much for the kind comments from reviewers. We have incorporated the suggested issues by the reviewers as follows.
Response to Reviewer 3 Comments
Point 1: In conclusion, I have no significant remarks on the work, except to check once again for typos (they occur here and there).
Response: Typo was corrected.
We believe that the revised manuscript is acceptable and published soon in Materials.
Sincerely,
Han-Gyeol Kim and Joonho Lee
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
To my opinion, the revised manuscript is not sufficiently improved to be suited for the publication in materials. The manuscript contains rather poor results on the one hand and still has a number of serious flaws on the other hand. What I count as a poor result, in the context of research in the field of the CALPHAD-method, is- only a model study with no connection to the experiment is discussed
- only a binary alloy and a regular solution approach is discussed
- only one eutectic system is discussed
- a ready to use commercial CALPHAD program has been used, and no discussion on method development is provided.
- The authors do not properly cite their own previous work. Especially, the citation [56-61] in line 40 is completely inappropriate in the present form. Non of these articles, each authored and co-authored by at least one of the three authors of the present manuscript, is mentioned elsewhere in the manuscript. The authors reaction: The authors just explain (to me), that I overlooked line 180, where they cite their articles in the exact same descriptionless way, without any valuable information about what in detail can be found where. Apart from that they decided not to improve their manuscript! To my opinion, this is an insufficient reaction.
- The model description is incomplete. For instance, following Eq. (26), it seams as if the excess volume is hidden somehow in the interaction parameter from the regular solution model. However, Fig. 4 tells that this parameter has been varied independently from interaction parameters. The authors reaction: The authors add a line in Eq. (24), which explains how the excess volume is relates to the interaction parameter. This, however, does not explain how these two parameters can be varied independently from each other. It rather supports, that they are truly not independent from each other. To my opinion, this is an insufficient reaction.
- It is not clearly discussed how the presented modeling results relate to experimental findings. The authors reaction: It seams as if also this comment did not motivated the authors to improve their manuscript in any respect. To my opinion, this is an insufficient reaction.
- It is not explained how (by which method) the phase diagrams are calculated from the Gibbs-free energy curves. The authors reaction: The authors added the following single sentence: “Phase diagrams were calculated by Gibbs energy minimization with FactSage software”. To my opinion, this is an insufficient reaction.
- The results are not at all sufficiently discussed. The authors reaction: The authors add a paragraph in the discussion. In this new paragraph the authors describe their results in words. This could be considered as an additional discussion, but it does not really add a value (such as an new perspective) to the manuscript. To my opinion, this is an inadequate reaction.
Author Response
Dear Reviewer 2,
Thank you very much for the kind comments from reviewers. We have incorporated the suggested issues by the reviewers as follows.
Response to Reviewer 2 Comments
Point 1: The authors do not properly cite their own previous work. Especially, the citation [56-61] in line 40 is completely inappropriate in the present form. Non of these articles, each authored and co-authored by at least one of the three authors of the present manuscript, is mentioned elsewhere in the manuscript.
Response: These articles (Refs. 56-61) were mentioned in line 180 also. These articles reported the calculation results of the pressure diagrams of various systems. Especially, in Refs. 59 and 60, the relation between the excess volume and the interaction parameter was reported in detail.
Point 1-1: 1. The authors just explain (to me), that I overlooked line 180, where they cite their articles in the exact same descriptionless way, without any valuable information about what in detail can be found where. Apart from that they decided not to improve their manuscript! To my opinion, this is an insufficient reaction.
Response: Thank you for the constructive comments. We have revised the manuscript by adding some detailed information.
Point 2: The model description is incomplete. For instance, following Eq. (26), it seams as if the excess volume is hidden somehow in the interaction parameter from the regular solution model. However, Fig. 4 tells that this parameter has been varied independently from interaction parameters.
Response: The equation (24) (old number 25) has been extended to show the relation between the excess volume and the interaction parameter.
Point 2-1: The authors add a line in Eq. (24), which explains how the excess volume is relates to the interaction parameter. This, however, does not explain how these two parameters can be varied independently from each other. It rather supports, that they are truly not independent from each other. To my opinion, this is an insufficient reaction.
Response: In our previous studies ([56]~[61]), we have examined this model to the calculation of the pressure diagrams up to several GPa. Within this range, the calculated results showed excellent agreement with the experimental data. Therefore, it is reasonable to assume that the excess volume would not be changed with pressure in this study. We have added some comments on that.
Point 3: It is not clearly discussed how the presented modeling results relate to experimental findings.
Response: The purpose of the present study is to provide a general principle on the direction of changes in phase stability of nanoparticles under pressure, which is first suggested in this paper. Applications to experimental results will be our future research topics.
Point 3-1: It seams as if also this comment did not motivated the authors to improve their manuscript in any respect. To my opinion, this is an insufficient reaction.
Response: In order to apply this model to practical applications, we need various thermophysical data (accurate surface tension, density and sound velocity), which should be investigated separately. These works also need tremendous time and efforts. Therefore, applications to experimental results will be our future research topics. I respect the reviewer’s opinion and agree that everyone may have a different opinion, but I have a different idea this time. All the research should be carried out step by step.
Point 4: It is not explained how (by which method) the phase diagrams are calculated from the Gibbs-free energy curves.
Response: The phase diagrams were calculated by Gibbs-free energy minimization with FactSage program. A new sentence was added in line 219.
Point 4-1: The authors added the following single sentence: “Phase diagrams were calculated by Gibbs energy minimization with FactSage software”. To my opinion, this is an insufficient reaction.
Response: It seems that the reviewer is not familiar with the CALPHAD method. CALPHAD is a globally well-recognized method (www.calphad.org), and FactSage is one of the most well-known and well-used software in this area. The phase diagrams calculated with FactSage program in this paper, would not be different from the calculated results with different software such as ThermoCalc, FactSage, OpenCalphad, etc. For additional information, we have included references to this software.
Point 5: The results are not at all sufficiently discussed.
Response: Additional discussion was included in line 288.
Point 5-1: The authors add a paragraph in the discussion. In this new paragraph the authors describe their results in words. This could be considered as an additional discussion, but it does not really add a value (such as an new perspective) to the manuscript. To my opinion, this is an inadequate reaction.
Response: This is the difference in writing style. I think that a good paper should clearly deliver the main concept of the research. Therefore, the main task is removing unnecessary parts from the manuscript. By doing that, we can clearly see the main idea suggested in the paper. For example, we have selected two sets of interaction parameters and three sets of excess volume parameters, although we have examined all other combinations. Why? Because we concluded that other results would be obstacles in understanding the main concept suggested in this paper. New perspective? It has been suggested in Fig. 3 and Fig. 4, already. For pure substance in general, the melting point of nanoparticles increases with increasing pressure. However, in this study, it was demonstrated that the eutectic point of nanoparticles (melting point of a binary sample) might decrease or increase with increasing pressure depending on the interaction parameter and excess volume. This is a very new perspective that has not been reported elsewhere before. I think that the reviewer considers a better paper should contain more discussions. This would be true for experiments-based papers. However, this would be not true for this type of paper. Nevertheless, additional figure was suggested in the revised manuscript to respect the reviewer’s opinion. If the reviewer think that the suggested information is useless, it can be removed in the final version.
We believe that the revised manuscript is acceptable and published soon in Materials.
Sincerely,
Han-Gyeol Kim and Joonho Lee
Author Response File: Author Response.pdf
