ACOM/TEM and EBSD Microstructure Characterization of ECAE-Processed Zirconium

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

referee report 

metals-2896475-peer-review-v2

ACOM/TEM and EBSD microstructure characterization of 2 ECAE processed zirconium

Mychelle Vianna Pereira Companhoni et al.

 

The present manuscript describes the characterization of ECAE processed Zr. The authors apply optical microscopy,

SEM, EBSD, TKD and TEM, and conclude that a combination of techniques may be required to properly characterize

the samples. This topic is indeed important for the readers of Metals, so the topic fits very well to the scope.

The manuscript comprises 7 figures, no table and 14 references are given.

The manuscript is well arranged but somewhat sloppy written. There are several flaws and omissions especially in

the description of the experimental procedures, e.g., WD is used instead of "working distance" without any 

definition, and abbreviations appear without definition or further explanation (e.g., TKD). Further, the angle

284.70° requires an explanation!

 

# What is the meaning of Bc?

# Chemical formulae should always be written properly (MoS2,...)

# Please format units properly (A/cm2)!

# There should always be a space between a physical quantity and its unit!

# The abbreviation for "hour" is h.

# What is the meaning of (a)       (b)      in line 109? These letters should go to the figures, and then

   (c) is missing!

# Please explain indexation quality map.

# The orientation map in Fig. 2 (c) requires a direction! I assume it is 0001 (i.e., perpendicular to the sample

   surface)? All scale bars are unreadable. Fig. 2 (d) is a stereographic triangle, which has nothing to do

   with an inverse pole figure!

# Fig.4: Please remove all nearly unreadable junk from the image and put it in the figure caption.

    (a): Please explain what a band contrast mapping means!

# Fig.5: The caption says "scale bar ~5 µm", and the images say 200 nm!!! What is correct?

# Fig.6: The dimensions are unreadable. Please provide proper ones!

# Reference list: It is remarkable that NO important general papers on EBSD or TKD are mentioned here!

 

Overall, this manuscript is still far away from being publishable, even though the topic is really interesting

to the readers. So, please provide the required information, and please add more analysis steps like grain

size determination, misorientation angles, grain boundaries, etc. Then, the manuscript will gain much more

importance!

 

 

 

Comments on the Quality of English Language

Moderate changes required

Author Response

There are several flaws and omissions especially in the description of the experimental procedures, e.g., WD is used instead of "working distance" without any definition, and abbreviations appear without definition or further explanation (e.g., TKD). Further, the angle 284.70° requires an explanation!

The revisions were done. Many thanks

 # What is the meaning of Bc?

The Bc route, which turns the sample 90° in the same direction between the subsequent passes.

# Chemical formulae should always be written properly (MoS2,…)

Corrected.

# Please format units properly (A/cm2)!

Corrected.

# There should always be a space between a physical quantity and its unit!

Corrected.

# The abbreviation for "hour" is h.

Corrected

# What is the meaning of (a)       (b)      in line 109? These letters should go to the figures, and then    (c) is missing!

Corrected

# Please explain indexation quality map.

Explained

# The orientation map in Fig. 2 (c) requires a direction! I assume it is 0001 (i.e., perpendicular to the sample  surface)? All scale bars are unreadable. Altered Fig. 2 (d) is a stereographic triangle, which has nothing to do with an inverse pole figure!

# Fig.4: Please remove all nearly unreadable junk from the image and put it in the figure caption.OK

    (a): Please explain what a band contrast mapping means!

Explained

 

 

# Fig.5: The caption says "scale bar ~5 µm", and the images say 200 nm!!! What is correct?

Corrected

# Fig.6: The dimensions are unreadable. Please provide proper ones!

Corrected

# Reference list: It is remarkable that NO important general papers on EBSD or TKD are mentioned here!

Included

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

The authors raise a very important topic, namely the characterization of ultrafine-grained structures (UFG) obtained by severe plastic deformations. The authors studied zirconium obtained by ECAE. Unfortunately, the evaluation of the paper revealed its very low scientific and practical value. The reasons are below.

1. The list of references does not completely cover the problem being studied. There is no reference to papers on processing zirconium using ECAP or ECAE, although there have been many such papers over the past 15-17 years. Here are just a few of them:

Journal of the Mechanical Behavior of Biomedical Materials. 6 (2012) 89-94. https://doi.org/10.1016/j.jmbbm.2011.05.034

Materials Science and Engineering: A. 449–451 (2007) 1087-1089. https://doi.org/10.1016/j.msea.2006.02.261

Acta Physica Polonica A. 122 (2012) 485–489. https://doi.org/10.12693/APhysPolA.122.485

Materials Letters. 169 (2016) 223–226. https://doi.org/10.1016/j.matlet.2016.01.148

Metal Science and Heat Treatment. 54 (2012) 407–413. https://doi.org/10.1007/s11041-012-9522-3

It is especially surprising that when discussing zirconium, the authors use references to titanium or even magnesium.

2. The Introduction is inadequate. In addition to the previous comment, I note that the authors consider only one point of view on the problems of UFG materials, in particular on the Hall-Petch relation, although there are several opinions on these issues in the literature.

3. The Materials and Methods part misses important details. What was the chemical composition of zirconium? Was it pure zirconium? What was the content of impurities? How many passes were implemented and how was the quantity determined? In what direction of the ECAE processed billet were the samples prepared for research? What is TKD?

4. The authors consider different methods for assessing UFG structures, but there is no depth of analysis. Moreover, there are no quantitative descriptions of the structure obtained by each of these methods. The authors argue that several methods should be used at once. This is fair and well known. However, this study does not provide information about how to evaluate structure using these methods. I don't see any value in this study.

5. The conclusion that the light microscopy was not an efficient tool for analyzing the UFG structures is not new.

6. The use of a large number of fields of view of DF images is widely practiced. Moreover, this is the most common way to quantify UFG structures.

Other:

Line 29. It is generally accepted that nanosize materials are materials with crystallite sizes less than 100 nm.

Line 37. The equation format is unacceptable. Apart from this, there are no explanations for the formula variables.

Line 40. What does ‘to obtain the mean grain size’ mean? To measure? And why the average grain size? If the size distribution differs from normal, then the average size is not adequate.

Line 55-56. ECAE is a method of obtaining a mainly submicrocrystalline structure rather than a nanocrystalline one.

 

Author Response

1. The list of references does not completely cover the problem being studied. There is no reference to papers on processing zirconium using ECAP or ECAE, although there have been many such papers over the past 15-17 years. Here are just a few of them:

Journal of the Mechanical Behavior of Biomedical Materials. 6 (2012) 89-94. https://doi.org/10.1016/j.jmbbm.2011.05.034

Materials Science and Engineering: A. 449–451 (2007) 1087-1089. https://doi.org/10.1016/j.msea.2006.02.261

Acta Physica Polonica A. 122 (2012) 485–489. https://doi.org/10.12693/APhysPolA.122.485

Materials Letters. 169 (2016) 223–226. https://doi.org/10.1016/j.matlet.2016.01.148

Metal Science and Heat Treatment. 54 (2012) 407–413. https://doi.org/10.1007/s11041-012-9522-3

It is especially surprising that when discussing zirconium, the authors use references to titanium or even magnesium.

It is because they are Thank you. We added the suggested references.

2. The Introduction is inadequate. In addition to the previous comment, I note that the authors consider only one point of view on the problems of UFG materials, in particular on the Hall-Petch relation, although there are several opinions on these issues in the literature. OK
3. The Materials and Methods part misses important details. What was the chemical composition of zirconium? Was it pure zirconium? What was the content of impurities? How many passes were implemented and how was the quantity determined? In what direction of the ECAE processed billet were the samples prepared for research? What is TKD?

Answered in the text.

4. The authors consider different methods for assessing UFG structures, but there is no depth of analysis. Moreover, there are no quantitative descriptions of the structure obtained by each of these methods. The authors argue that several methods should be used at once. This is fair and well known. However, this study does not provide information about how to evaluate structure using these methods. I don't see any value in this study.

The papers describe the grain sizes of the structures but only for the BF and DF images. Our work aims to discuss the need of complementary techniques to describe the microstructure of ultrafine and nanocrystalline metals, specially the heterogeneous.

5. The conclusion that the light microscopy was not an efficient tool for analyzing the UFG structures is not new.

Corrected.

 

6. The use of a large number of fields of view of DF images is widely practiced. Moreover, this is the most common way to quantify UFG structures.

The discussion also comments the different sizes of highlighted grains as different spot diameters are selected.

Other:

Line 29. It is generally accepted that nanosize materials are materials with crystallite sizes less than 100 nm.

Changed.

Line 37. The equation format is unacceptable. Apart from this, there are no explanations for the formula variables.

Explained.

Line 40. What does ‘to obtain the mean grain size’ mean? To measure? And why the average grain size? If the size distribution differs from normal, then the average size is not adequate.

Corrected.

Line 55-56. ECAE is a method of obtaining a mainly submicrocrystalline structure rather than a nanocrystalline one.

Corrected.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper describes different diffraction related grain size characterization method using ECAE processed zirconium sample. It is a good work to show the pros and cons of different method. 

I recommend acceptance with revision.

 

-Line 106 and Fig.1a: Please explain or describe the microstructure of the annealed sample. What are the features, such as the lines in the image?

-Line 113 to line 117: Please explain Fig2b contrast in more details and more clearly. What are those thin dark lines within the grains? The shear bands?  More explanation on the indexation quality map.

-Line 219: Fig7a: “from the intersection of lines shown in (a)”, Where are the lines in Fig. (a)?

Maybe the authors can add another figure to show the nanodiffraction pattern and indicate the corresponding aperture?

 

-Fig. 5: Can the authors put the nanodiffraction pattern with indication of aperture location as insets in (b-f)? 

 

-Line 194-203:  A better, more clear and detailed explanation of the DF image is needed. The current explanation is not clear. Do you mean that the DF grain is only partially highlighted due to misorientation?

 

 

-Line 231: “metals field.”, is ‘metallurgy field’ better?

-Line 235: it should be “correctly reveal..”

Comments on the Quality of English Language

Good.

Author Response

 -Line 106 and Fig.1a: Please explain or describe the microstructure of the annealed sample. What are the features, such as the lines in the image?

Light microscopy is shown as annealed zirconium with Widmanstätten structure.

 

-Line 113 to line 117: Please explain Fig2b contrast in more details and more clearly. What are those thin dark lines within the grains? The shear bands?  More explanation on the indexation quality map.

The quality map is a metric describing the quality of a diffraction pattern. It is construct-ed by mapping the value measured for each diffraction pattern obtained during an ori-entation imaging microscopy (OIM) scan to a gray or color scale.

 

-Line 219: Fig7a: “from the intersection of lines shown in (a)”, Where are the lines in Fig. (a)? Maybe the authors can add another figure to show the nanodiffraction pattern and indicate the corresponding aperture?

 

The image of the intersection of the lines was included. We added another figure to explain it Fig. 8 

 

 

-Fig. 5: Can the authors put the nanodiffraction pattern with indication of aperture location as insets in (b-f)? 

 

Unfortunately no. I don´t have this patterns. My advisor died and there are some images that I can´t get anymore.

 

-Line 194-203:  A better, more clear and detailed explanation of the DF image is needed. The current explanation is not clear. Do you mean that the DF grain is only partially highlighted due to misorientation?

 

As well as the size o the chosen spot.

-Line 231: “metals field.”, is ‘metallurgy field’ better?

Changed

-Line 235: it should be “correctly reveal..”

Corrected

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Well performed revision. Appropriate changes were made to the manuscript, which is now suitable for publication in its present form.

One minor comment: What is Ref. [10]?

Comments on the Quality of English Language

English improved, minor editorial changes required

Author Response

Thank you for your comments and revision.

The reference was added.

 

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

The revision obviously improved the manuscript. While the manuscript can be accepted as is, I would like to see more in-depth analysis in the authors' work.

Author Response

Many thanks for your comments and revision.

Unfortunately, I cannot provide more in-depth analysis as my advisor, Prof. Dr. Andre Pinto, has passed away. However, based on your comments, it seems that the manuscript can be accepted as is.