Influence of a Protective Coating on the Crystallization of an Amorphous Fe₇₈Si₁₃B₉ Alloy

Round 1

Reviewer 1 Report

The manuscript investigate the effect of shearing via ultrasonic treatment and covering the surface with a coating on crystallization kinetics of a metallic glass. The main finding is that both shearing and coating result in enhancement of crystallization kinetics. The authors interpret this outcome as resulting from the ability of shearing to increase free volume and coating to hinder free volume release at the interface.

 

This is an interesting piece of work showing how free volume amount in a supercooled melt can be tuned to favor or retard crystallization. Given these premises, the present manuscript can be recommended for publication after amendments, as detailed below:

 

1.      The most important aspect requiring careful consideration is that the amount of free volume can be varied via diffusion at free interfaces. I recommend that the authors consider the following works where the diffusion of free volume at free interfaces has been shown to affect the glass transition temperature in nanostructructed glasses: Prog. Pol. Sci. 54-55, 128-147 (2016); and direct visualization of free volume diffusion was shown in colloidal glasses: Nat. Comm. 8, 362 (2017). Though these results were shown in non-metallic glasses, the concept of free volume diffusion appears to be universal for all kinds of glasses. Hence, the manuscript would certainly benefit from a discussion on such universal aspects.

 

2.      Line 64: “However, during structural relaxation, heat treatment, or simply 64 aging, the amount of free volume decreases”. Clarify the thermodynamic driving force for such a decrease.

 

3.      Line 69: “free volume must be prevented.” Here is free volume “diffusion”.

 

4.      Figure 2: The completely amorphous sample should display the glass transition. Is this below 700 K? In any case, it is good to show it the DSC scan below that temperature.

 

5.      Line 226: “Under heat treatment, structural relaxation occurs, which is accompanied by a de-226 crease in the free volume by 2% [51].” In ref. 51 no results on density variation upon thermal treatment is reported. A more appropriate reference on physical aging after a temperature jump is required.

Author Response

Dear Editor and Reviewers,

 

We would like to resubmit our manuscript (Metals ID:  metals-2423097) after revisions. Thank you very much for your suggestions which indeed help us to improve the present manuscript. Those comments are all valuable and very helpful for revising and improving our paper. We revised the manuscript based on your suggestions, and all the modifications were written in blue text in the revised manuscript.

 

1. The most important aspect requiring careful consideration is that the amount of free volume can be varied via diffusion at free interfaces. I recommend that the authors consider the following works where the diffusion of free volume at free interfaces has been shown to affect the glass transition temperature in nanostructructed glasses: Prog. Pol. Sci. 54-55, 128-147 (2016); and direct visualization of free volume diffusion was shown in colloidal glasses: Nat. Comm. 8, 362 (2017). Though these results were shown in non-metallic glasses, the concept of free volume diffusion appears to be universal for all kinds of glasses. Hence, the manuscript would certainly benefit from a discussion on such universal aspects.

Additions and references have been added to the text (lines 46-51, 64-73, 93-105).

2. Line 64: “However, during structural relaxation, heat treatment, or simply aging, the amount of free volume decreases”. Clarify the thermodynamic driving force for such a decrease.

Additions and references have been added to the text (lines 108-113).

3. Line 69: “free volume must be prevented.” Here is free volume “diffusion”.

The text has been corrected (lines 126-127). 

4. Figure 2: The completely amorphous sample should display the glass transition. Is this below 700 K? In any case, it is good to show it the DSC scan below that temperature.

 In the alloy under study, the glass transition temperature is higher than the crystallization temperature. Below 700K, there are no features on the DSC curve.

5. Line 226: “Under heat treatment, structural relaxation occurs, which is accompanied by a decrease in the free volume by 2% [51].” In ref. 51 no results on density variation upon thermal treatment is reported. A more appropriate reference on physical aging after a temperature jump is required.

This is a typo. The text has been corrected (line 358).

 

Author Response File: Author Response.pdf

Reviewer 2 Report

This article is interesting to compared the Fe77Si13B10 glassy ribbon under the Ta coating and nake sample in crystallization. However, there are some questions to answer, after that, it can be published in metals:

1)Ultrasonic treatment has been plused with Ta coating. If with out coating, the ribbon after ultrasonic treatment was compared with control sample, the conclusion will be more clear and direct.

2)About the crstallization, it is adviced to refer the article in Thermochimica Acta (661 (2018), 67-77), and authors can get more information in the glassy ribbon.

3)Fig. 7, if authors give SADP, it willl be better.

4)The free volume is not resolved in this article, it can be omitted in the title, to aviod an overexplain feeling.

 

 

ok

Author Response

Dear Editor and Reviewers,

 

We would like to resubmit our manuscript (Metals ID:  metals-2423097) after revisions. Thank you very much for your suggestions which indeed help us to improve the present manuscript. Those comments are all valuable and very helpful for revising and improving our paper. We revised the manuscript based on your suggestions, and all the modifications were written in blue text in the revised manuscript.

 

• Ultrasonic treatment has been plused with Ta coating. If with out coating, the ribbon after ultrasonic treatment was compared with control sample, the conclusion will be more clear and direct.

Such a comparison is shown in Fig. 9. Fig. 9 shows X-ray diffraction patterns of the annealed samples (without ultrasonic treatment (1) and after ultrasonic treatment (2)). The fraction of the crystalline phase formed in sample 2 (after US pretreatment) is slightly larger than the fraction of the crystalline phase formed in sample 1 (control sample). The observed difference is small; therefore, to enhance the effect of US on crystallization and increase the fraction of the crystalline phase in the sample, a protective Ta coating was then applied.

We have added secondary titles to the “Results”, and we hope this makes the results more understandable.

 2)About the crystallization, it is adviced to refer the article in ThermochimicaActa (661 (2018), 67-77), and authors can get more information in the glassy ribbon.

Additions and references have been added to the text (lines 68-73).

3)  Fig. 7, if authors give SADP, it willl be better.

The SADP has been added (Fig. 7b).

4)The  free volume is not resolved in this article, it can be omitted in the title, to aviod an overexplain feeling.

The manuscript title has been changed.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

In this manuscript, the authors studied the effects of Ta layer, heat treatment and ultrasonic treatment on the free volume concentration of non-crystalline materials during the crystallization process, which has important guiding significance for the acquisition of nanocrystalline materials. However, the analysis in this part of the manuscript lacks sufficient experimental data supports and the interpretation of experimental results is not clear enough. Therefore, it is recommended that the author fully revises the manuscript before publication. In addition, there are several major problems.

1. The analysis results of Figure 1-4 are very common to the research field of this material, so it is of little significance of the author to elaborate on too much space.

2. In Figure 4, the authors state that "the information obtained by electron microscopy is local. Therefore, in further comparative studies, the main concern is the analysis of X-ray diffraction results." However, XRD analysis method also has drawbacks. The author used X-ray diffraction to analyze the results almost all the time, and I think the obtained results are not rigorous enough.

3. The thickness of Ta layer can be marked in Figure 5 for the convenience of readers.

4. Figure 6 and Figure 8 both describe the influence of Ta layer, so it is recommended that the author merges them.

5. XRD can obtain specific grain size and Grain volume fraction through fitting. It is suggested that the author conducts quantitative processing of relevant data to facilitate direct comparison results.

    6. The author has comparative analysis of several experimental results of the manuscript. When there are too many experimental variables, it is suggested that the author should number and classify them reasonably and put them in the part of "Materials and Methods". In addition, for ease of reading, it is suggested to add secondary titles to the section description in the part of "Results and Discussion".

There are a few grammatical errors in the manuscript. Please check it carefully and correct it.

Author Response

Dear Editor and Reviewers,

 

We would like to resubmit our manuscript (Metals ID:  metals-2423097) after revisions. Thank you very much for your suggestions which indeed help us to improve the present manuscript. Those comments are all valuable and very helpful for revising and improving our paper. We revised the manuscript based on your suggestions, and all the modifications were written in blue text in the revised manuscript.

 

 

1. The analysis results of Figure 1-4 are very common to the research field of this material, so it is of little significance of the author to elaborate on too much space.

 In principle, we could agree with this remark; however, reviewer 2 recommended expanding this part.

2. In Figure 4, the authors state that "the information obtained by electron microscopy is local. Therefore, in further comparative studies, the main concern is the analysis of X-ray diffraction results." However, XRD analysis method also has drawbacks. The author used X-ray diffraction to analyze the results almost all the time, and I think the obtained results are not rigorous enough.

We do not agree with this remark of the reviewer. In many studies, it is X-ray diffraction studies that determine structural transformations in an amorphous structure. When analyzing the X-ray diffraction patterns of samples containing amorphous and crystalline phases, the maxima were decomposed into components: a diffuse maximum from the amorphous phase and a diffraction reflection from the crystals. In this case, the parameters of the diffuse maximum of the initial amorphous alloy were taken into account. Based on the determined values of the integral intensities of the submaxima, change in the proportion of the amorphous (or crystalline) component of the structure was calculated.  It is very difficult to correctly estimate the proportion of one or another structural component according to the data of electron microscopic studies.

An additional part has been added to the text (lines 163-179, 224-232).

 

3. The thickness of Ta layer can be marked in Figure 5 for the convenience of readers.

The thickness of a Ta layer has been marked in Fig. 5.

4. Figure 6 and Figure 8 both describe the influence of Ta layer, so it is recommended that the author merges them.

It seems to us that Figures 6 and 8 should be left both. Fig. 6 shows the overall change in the XRD patterns. Fig. 8 shows the division of the main maxima into parts due to scattering from the amorphous phase and a diffraction reflection from the nanocrystals.  Figure 8 shows that the diffraction peaks in these samples have different intensities. This is an important result of the study.

5. XRD can obtain specific grain size and Grain volume fraction through fitting. It is suggested that the author conducts quantitative processing of relevant data to facilitate direct comparison results.

We did indeed quantify the relevant data to directly compare the results. Processing data has been added to the “Materials and Methods” part (lines 163-179).

6. The author has comparative analysis of several experimental results of the manuscript. When there are too many experimental variables, it is suggested that the author should number and classify them reasonably and put them in the part of "Materials and Methods". In addition, for ease of reading, it is suggested to add secondary titles to the section description in the part of "Results and Discussion".

In our opinion, this is a very useful observation that allows a more understandable display of the results. We have added secondary titles to the section description in the   "Results and Discussion" part.

There are a few grammatical errors in the manuscript. Please check it carefully and correct it.

The text has been corrected.

 

 

Author Response File: Author Response.pdf

Reviewer 4 Report

 

1.     “…The width of the ribbons was 1 cm, and the thickness was about 35 microns….” With the melt spinner process is impossible to produce ribbons of 1 cm (width); did you use planar flow casting? Including the casting conditions would clarify this point.

2.     Was the Ta coating also amorphous?

3.     Including the phase(s) (in addition to the hkl) in the corresponding Bragg peaks obtained in all XRD patterns reported would be convenient.

4.     Adding the diffraction patterns of the TEM analysis is also convenient, indexing the TEM patterns and comparing them with the XRD would enhance the discussion.

Author Response

Dear Editor and Reviewers,

 

We would like to resubmit our manuscript (Metals ID:  metals-2423097) after revisions. Thank you very much for your suggestions which indeed help us to improve the present manuscript. Those comments are all valuable and very helpful for revising and improving our paper. We revised the manuscript based on your suggestions, and all the modifications were written in blue text in the revised manuscript.

 

1. The width of the ribbons was 1 cm, and the thickness was about 35 microns….” With the melt spinner process is impossible to produce ribbons of 1 cm (width); did you use planar flow casting? Including the casting conditions would clarify this point.

Amorphous Fe₇₈Si₁₃B₉ was obtained by quenching the melt in the form of ribbons. When preparing  the samples, capillaries with a slotted hole were used. The text has been corrected (lines 141-143).

2. Was the Ta coating also amorphous?

The Ta coating was crystalline; it consisted of small randomly oriented crystals.

3. Including the phase(s) (in addition to the hkl) in the corresponding Bragg peaks obtained in all XRD patterns reported would be convenient.

The phase information has been added to the Figures.

4. Adding the diffraction patterns of the TEM analysis is also convenient, indexing the TEM patterns and comparing them with the XRD would enhance the discussion.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors revised the manuscript to make it more rigorous, and it is good enough to be published in the journal. But the current form of introduction is inappropriate. it's long and spend a lot of readers' time with obvious details. Please simplify this part before the manuscript is published. In addition, the format of the manuscript is not standard and the author needs to modify it.

The English language and format need to be checked and modified

Author Response

The authors are grateful to the reviewer for their attentive attitude to our article. The changes made on his recommendation have undoubtedly made it possible to improve the article.

• We shortened the "Introduction" part a bit. However, we would like to note that this part has been enlarged in accordance with the comments of other reviewers. For example,

Reviewer 1:

The most important aspect requiring careful consideration is that the amount of free volume can be varied via diffusion at free interfaces. I recommend that the authors consider the following works where the diffusion of free volume at free interfaces has been shown to affect the glass transition temperature in nanostructructed glasses: Prog. Pol. Sci. 54-55, 128-147 (2016); and direct visualization of free volume diffusion was shown in colloidal glasses: Nat. Comm. 8, 362 (2017). Though these results were shown in non-metallic glasses, the concept of free volume diffusion appears to be universal for all kinds of glasses. Hence, the manuscript would certainly benefit from a discussion on such universal aspects.

Reviewer 2:

About the crystallization, it is adviced to refer the article in ThermochimicaActa (661 (2018), 67-77), and authors can get more information in the glassy ribbon.

• The format of the manuscript was changed due to recommendation of reviewer 3:

In addition, for ease of reading, it is suggested to add secondary titles to the section description in the part of "Results and Discussion".

• Manuscript has been checked by English speaker

Author Response File: Author Response.pdf