Effects of Cooling Rate on the Solidification Process of Pure Metal Al: Molecular Dynamics Simulations Based on the MFPT Method
Round 1
Reviewer 1 Report
Dear authors,
The manuscript you submitted was comprehensibly structured and very easy to read. The inserted graphs are well labeled, noted in the text, and easy to understand. From my point of view, I have no reservations about the publication of your submitted manuscript. However, I must note that the method you used is not in my field of expertise and therefore I cannot evaluate this part.
Enclosed are a few comments on the layout of your manuscript, although these are only matters of style.
54: The only abbreviation used here is MD not with the full name Molecular Dynamics. Here I recommend to writing out all abbreviations for the sake of uniformity.
70-71: Whether one writes out FFC and HCP as lattice structure also once completely is a question of the style to write out all abbreviations once.
Figures: The coloring of the HCP and FCC atoms could be more intensive.
243: In table 4 one should mention n* in the text since there is also a column for it.
Author Response
Response to Reviewer 1 Comments
We would like to thank the reviewer 1 providing many professional comments in our manuscript, entitled “Effects of Cooling Rate on the Solidification Process of Pure Metal Al: Molecular dynamics simulations based on the MFPT method”. We have revised our manuscript according to these comments. Changes made are highlighted in red in the marked-up manuscript. The detailed responses are shown as follows (highlighted in red). We hope it will satisfy the concerns about the manuscript.
Reviewer 1 comments:
Point 1: Line 54: The only abbreviation used here is MD not with the full name Molecular Dynamics. Here I recommend to writing out all abbreviations for the sake of uniformity.
Response: We thank the reviewer for the recommendation. All abbreviations have been written in the revised version (line 48-51).
Point 2: Line 70-71: Whether one writes out FCC and HCP as lattice structure also once completely is a question of the style to write out all abbreviations once.
Response: We thank the reviewer for this useful comment. The full names of FCC and HCP have been written in the revised version (line 67-69).
Point 3: Figures: The coloring of the HCP and FCC atoms could be more intensive.
Response: We thank the reviewer for this professional comment. The contrast of the graphs regarding FCC and HCP in the article has been modified to make it more intensive.
Point 4: In table 4 one should mention n* in the text since there is also a column for it.
Response: We thank the reviewer for this professional comment. The n* has been mentioned in the text in table 4 in the revised version (line 247).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors presented the results of molecular dynamics simulations of pure Al discussed the effect of cooling rate on the solidification process. The results contain interesting results which merit publication in metals. However, there are several problems for publication as listed below.
The structure of Al melt is shown in Fig.1 (a). However, the arrangement of atoms cannot be identified in Fig.1 (a). A magnified view will support the readers to understand the structure of Al melt.
In line 164-165 “proving that there are energy fluctuations inside the supercooled Al melt” It is not clear what the energy fluctuation means. Does the energy fluctuation mean a dip at -7.5 nm in Figure 3 (b)? Or change in energy at around -3.22 eV observed from -15 to 15 nm?
In line 228, “c denotes the local curvature at the top of the barrier” No information about the barrier is provided. The authors should describe the detail of the barrier.
Author Response
Response to Reviewer 2 Comments
We would like to thank the reviewer 2 providing many professional comments in our manuscript, entitled “Effects of Cooling Rate on the Solidification Process of Pure Metal Al: Molecular dynamics simulations based on the MFPT method”. We have revised our manuscript according to these comments. Changes made are highlighted in red in the marked-up manuscript. The detailed responses are shown as follows (highlighted in red). We hope it will satisfy the concerns about the manuscript.
Reviewer 2 comments:
Point 1: The structure of Al melt is shown in Fig.1 (a). However, the arrangement of atoms cannot be identified in Fig. 1(a). A magnified view will support the readers to understand the structure of Al melt.
Response: We thank the reviewer for the recommendation. Magnified view of Al melt has been added to Figure 1(a) in the revised version (line 120-122).
Point 2: In line 164-165 “proving that there are energy fluctuations inside the supercooled Al melt” It is not clear what the energy fluctuation means. Does the energy fluctuation mean a dip at -7.5 nm in Figure 3 (b)? Or change in energy at around -3.22 eV observed from -15 to 15 nm?
Response: We thank the reviewer for this useful comment. The energy fluctuation means the change in potential energy at around -3.22 eV observed from -15 to 15 nm. However, the energy fluctuations around the nucleation region are the largest, relevant explanations have been added to the text (line 165-166).
Point 3: In line 228, “c denotes the local curvature at the top of the barrier” No information about the barrier is provided. The authors should describe the detail of the barrier.
Response: We thank the reviewer for this professional comment. c denotes the local curvature at the top of the free energy barrier, relevant explanations have been added to the text (line 232).
Author Response File: Author Response.pdf
Reviewer 3 Report
Reviewer's comments are attached as a file.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 3 Comments
We would like to thank the reviewer 3 providing many professional comments in our manuscript, entitled “Effects of Cooling Rate on the Solidification Process of Pure Metal Al: Molecular dynamics simulations based on the MFPT method”. We have revised our manuscript according to these comments. Changes made are highlighted in red in the marked-up manuscript. The detailed responses are shown as follows (highlighted in red). We hope it will satisfy the concerns about the manuscript.
Reviewer 3 comments:
Point 1: Line 25 on page 1: The statement “The solidification process includes the nucleation andgrowth processes of crystals or grains when the melt is cooled” is true for singlecomponent systems. In the case of multi-component systems, crystallization can becompletely suppressed at high cooling rates.
Response: We thank the reviewer for the recommendation. “The solidification process includes the nucleation andgrowth processes of crystals or grains when the melt is cooled” has been changed to “The solidification process of pure metal includes the nucleation and growth processes of crystals or grains” in the revised version (line 25).
Point 2: Lines 25-46 on pages 1-2: These two paragraphs should be rewritten. In these paragraphs,many complex sentences and phrases that are not explained. For example, what "experimental constraints" are talking about in line 37?
Response: We thank the reviewer for this useful comment. These two paragraphs have been rewritten in the revised version (line 25-44).
Point 3: Line 100 on page 3: In work, the simulation is carried out in the NPT ensemble. Therefore, authors should indicate pressure values.
Response: We thank the reviewer for this professional comment. In this study, All simulations were performed at pressure of 0 MPa. The relevant description has been noted in the revised version. (line 108-109).
Point 4: The results presented in Tables 1 and Figure 2 should be discussed in more detail. It seems that the conditions for obtaining structures from Table 1 contradict the conditions from Figure2.
Response: We thank the reviewer for this professional comment. Conditions for obtaining structures from Table 1 do not contradict the conditions from Figure 2. In this work, the solidification process includes quenching followed by isothermal annealing. Figure 2 shows the quenched structures after quenching at different cooling rates. Table 1 shows the annealed structures. Previous caption for Table 1 is “Table 1. Structure of Al melts cooled at different cooling rates after isothermal heating for 1000 ps at different temperatures, where T is the temperature.”, which was incorrectly written. The correct caption for Table 1 is “Table 1. Three-dimensional structure snapshot of Al melts isothermally heated for 1000 ps at different temperatures after cooled at different cooling rates, where T is the annealing temperature.” We have revised the caption of Table 1 in the revised version.
Point 5: Are the structures in Figure 2 as well as in Tables 2 and 3 three-dimensional or two-dimensional? If the structures are three-dimensional, then this must be written in the captions or on the figures.
Response: We thank the reviewer for this professional comment. The structures in Figure 2 as well as in Tables 2 and 3 are three-dimensional, which have been added in the revised version.
Point 6: There is a mistake in the caption to Figure 4. The cooling rate 2*1012K/s is repeated twice.
Response: We thank the reviewer for this professional comment. One “2*1012K/s“has been replaced by “2*1013K/s” in the revised version. We are sorry for this carelessness.
Point 7: The paper should discuss the MFPT method in more detail.
Response: We thank the reviewer for this professional comment. The MFPT method has been written in more detail in the revised version.
Point 8: The paper should describe in more detail the procedure for averaging growth curves (Fig.4). Averaging greatly affects the final MFPT-curve. Here, it is more correct to use theinverted averaging method described in Refs. [J. Chem. Phys. 140,024104(2014); Phys. Chem. Chem. Phys. 19, 11340 (2017)]. At inverted averaging, the MFPT-curves aresmoother and have the correct inflection point, which makes it possible to accurately estimate the nucleation parameters.
Response: We thank the reviewer for this professional comment. The procedure for averaging growth curves in Figure 4 has been written in more detail. We also thanks to the reviewers for suggesting a better method of MFPT, which has been quoted in the revised version and will be adopted in future simulation studies.
Point 9: Table 4: How do the obtained dependences of the critical size and nucleation rate on thecooling rate agree with the known literature data (there may be data for other types of systems)?
Response: We thank the reviewer for this professional comment. In this work, the solidification process includes quenching followed by isothermal annealing. Effects of different cooling rates on the nucleation rate and critical nucleation radius under the same supercooling degree during the isothermal process are studied. There is little known literature data about dependences of the critical size and nucleation rate on cooling rate in previous studies for pure metal.
Point 10: In conclusion, a discussion of the obtained results from the point of view of their fundamental and practical significance should be added.
Response: We thank the reviewer for this professional comment. The fundamental and practical significance of this study have been added in the revised version.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors took into account all comments and made appropriate corrections to the manuscript. In the present form, the manuscript can be recommended for publication.
