Faceting and Twin–Twin Interactions in {1121} and {1122} Twins in Titanium
Round 1
Reviewer 1 Report
This study deals with the analytical description of the twin interfaces and facets structure under various twinning events in HCP metals. Such interface structure and twinning-related phenomena, like emissary slip at twin tip, growth and termination of twin, are crucial also to understand the twin-twin as well as twin-slip interaction. Moreover, the introduction of the present manuscript provides a well-summarized overview on the research activities in characterization of interface structures. The reviewer suggests the publication of the present manuscript, after addressing the following comments:
- the computation results are given to nine decimal places. The reviewer is wondering whether such high accuracy of numerical calculation is necessary. For example, the rotation angle of 2.40129645° or 2.59712319° seems to be meaningful in numerical calculation, but less-practical.
- some typos are to be corrected, e.g. microstrures, “…In this work we used the Meam/spline [40] and RANN [43] potentials The twin–twin interaction processes should be expected…”
Author Response
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Reviewer 2 Report
Twin-twin interactions are an important component of the microstructural evolution of hexagonal close-packed metals undergoing plasticity. These interactions are prevalent because of the predominance of twinning due to limited easy slip modes. Despite their importance, the complexities of the atomic scale behavior of interacting twins has limited robust characterization. Using interfacial defect theory, we have developed a three-dimensional model of twin-twin interactions, double twinning, and other complex interfacial reactions which occur between twins acting on different
interface planes. Using molecular dynamics, {1 1 2 2} and {1 1 2 1} twins in titanium were activated and produced facets, twin-twin interactions, and double twins which we characterized with our model. The results showed excellent agreement between the molecular dynamics results and the
model. Surprisingly, some highly ordered and mobile boundaries can be produced by these complex reactions, which could provide important insights for higher scale models of plasticity.
Author Response
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Reviewer 3 Report
This work, with its equations, its three dimensional analytic approach, its simulations using LAMMPS with two different potentials, one of them being a recently developed machine learrned interatomic potential, and its interpretations of the resuts looks sound to me.
I have no objection to the Authors using IDT (interfacial defect theory) and trichromatic complexes when they recall that some authors prefer other approaches.
I must confess I have not checked all symbols and numerics in the equations/matrices but a cursory perusal did not allow me to find any odd notation or spelling or typo. A valuable achievement in itself for a 30 page manuscript.
- One exception, though, page 17:
3.2.3. The {2114} twin facet -> The {2-1-14} twin facet.
The Authors write "In general, every hcp twin may produce a facet onto its conjugate twin interface. We observed this in our MD results with the MEAM/Spline potential, but not the RANN potential."
- Does that statement mean that the MEAM/spline 2008 potential is eventually better than the RANN 2021 potential? It would be valuable to recall this in the final conclusions.
- Also, what is meant by "In general"? Could some reference be given? The "may" auxiliary verb seems to imply some intuitively reasonable principle of symmetry, but the results obtained with the RANN potential infirm this principle. Could the Authors elaborate a little on this conceptually/physically surprising result?
It thus believe the proposed manuscript can almost be published as such, provided the Authors can add a few words about the previous point(s).
End of the report.
Author Response
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Reviewer 4 Report
Twinning in HCP structures is an interesting subject.
This is a paper related to "molecular dynamic simulation". For this reason, there is not experimental work.
The paper is too long (30 pages). Authors have two choices: to synthesize or to divide the paper in two.
The expression "MEAM" (in 2.1) must be defined as "Modified embedded atom method"
The expression "RANN" (in 2.1) must be defined as "Rapid Artificial Neural Network" the first time that is cited
The expression "DFT" (in 2.1) must be defined the first time that is cited
In all cases, separate the number from the units. Example: 21,2 nm
What's meaning "I" in eq. 3?
What's meaning "c" in eq. 5?
What is gamma in eq. 37?
Details of results could be included in an appendix (eqs. 39 to 42; 43 to 46; 47 to 52; 53 to 62 and so on ).
Authors must effort to resume the information.
Comments for author File: Comments.pdf
Author Response
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Reviewer 5 Report
This study thoroughly analyzes the twin-twin interactions and faceting in twins in hcp structures as twin-twin interactions significantly influence the formability and hardening of these structures. I would like to congratulate to the authors for this excellent work as they carefully described and modelled the interactions and faceting and they pointed out the importance of these kind of interactions. I recommend a minor revision of the paper and my suggestions in order to improve the manuscript are:
- Please, describe the caption of the Figure 1 in detail and carefully - what can be seen in Figure 1 a) and b) ? The same suggestion is valid for the caption of Figure 9 (a) and b)).
- Please, check the manuscript for typographical errors, such as "microstrures" should be ""microstructures" in the section Introduction, end of the line 9.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Despite the fact that I think the article is very long, I understand the reasons of the authors.
