Effect of Warm Crossing Rolling on the Microstructure, Texture and Annealing Behavior of High-Purity Tantalum

Round 1

Reviewer 1 Report

Thank you for this submission.  As a reader, I struggled to identify the central thesis of this paper.  For instance, sputtering targets was listed as a potential driver for this study.  However, no information regarding the problems with current targets or the ideal features for future targets was described.  In addition, several aspects of rolling of other materials (like Ti) was shared but the compilation of Ta rolling research was summated in a single sentence. 

 1)      Please consider providing more detail as to what the gaps are within the Ta rolling literature.

 2)      As Ta is a BCC material, consider using examples of other metals that are either BCC or that have high SFEs (like Ta) as a comparison.

 3)      Provide some context for your results with respects to industrial needs.  Even something as small as ‘reduction of dislocation content for performance enhancement’ is enough to help tie your results to the fundamental driver for your research.

 4)      Re-construct your abstract to end with a larger conclusion.  The bits and pieces of conclusions sound unrelated and fail to provide a context for why this should be published.

As I read through the paper, I struggled to determine how representative the results were that you shared.  This largely stems to the lack of clarity within the grain size measurements and the lack of labeling with respect to texture.

 5)       Figure 4 – why are pole figures included?  The ODFs provide the information that you compare against.  The pole figures seem superfluous. 

 6)      Line 126 – what is the angular resolution you used to define an orientation?  For instance, when I look at Figure 5 – the orientation information, I assume, is not a point in ODF space but rather a distribution.

 7)      Figure 5 – where was this data extracted from?  EBSD patterns?

 8)      Figure 6 – largely unlabeled.  What are the axes?

 9)      Figures 7 and 8 – shear bands were not clear.  Consider marking them within the images as it was difficult for me to see them in some of the images in Figure 7.

 10)   Figure 12 might be more effective as a table.  The plots seem to lose value above 20 degrees in misorientation angle.  Perhaps this can be improved for the reader’s sake.

 11)   Figure 13 – misspelled words are apparent in the y-axis descriptor for both a and b.  In addition, it is unclear why 10^5 was chosen when all the numbers are decimals.  Why not label 5 on figure 13a with the appropriate y-axis multiplier?

 12)   Figure 14.  Earlier in Figure 5 you choose to not include boundary grains.  Here you seem to have quite a few.  How does that change your result?  And why did you make the decision to include them in Figure 14 and not in Figure 5?

As I read through the discussion, I found a significant portion recreating textbook or other treatments of drivers for texture.  I found much of the discussion fairly rote and unimportant.  Do the results point to a fundamentally new understanding?  It does not appear that way.  Rather, these results are largely expected.  The discussion can be trimmed and literature utilized to indicate that results are as anticipated. 

 13)    Conclusions were largely supported by the data (except when the data was unclear as was pointed out earlier).  Point to explicit gaps in literature that these conclusions help fill.  In my survey of the literature you provided, there was little here that was fundamentally new, but you were ensuring that data was now being reported in open literature.

 14)   Conclusion #1 fails to point to friction between the rolling mill and the Ta material.  Was lubrication utilized in this study?  What if it had?  Consider extending some of your conclusions to point to future experimental needs.

Last thoughts:  There were no significant problems with this paper, but the overall purpose and impact to the field were difficult to discern.  The lack of scientific drivers was apparent as the conclusions were shared.  By providing correction to the experimental results description, this paper can at least provide novel data sets for texture modeling work.

Author Response

Dear editor,

The authors appreciate the helpful comments provided by reviewers. The revisions addressing the issues and comments are listed and explained below, in addition to those revisions and corrections from our own considerations. To facilitate the review process, response to each of the issues and comments is presented item by item and changes in the manuscript are highlighted in red.

Manuscript (No.: metals-2305866)

Reviewer#1:

1 Please consider providing more detail as to what the gaps are within the Ta rolling literature.

RE: Thanks for the advice.                                         

We have provided more detail as to what the gaps are within the Ta rolling literature.

The text is revised as following.

• “Previous studies have exhibited that 135° cross-rolling could more effectively improve the microstructure and texture homogeneity of Ta plates along the thickness direction than the conventional unidirectional rolling (UR) [5-10].” (line38)

Change to:

“Previous studies have exhibited that 135° cross-rolling could more effectively improve the microstructure and texture homogeneity of Ta plates along the thickness direction than the conventional unidirectional rolling (UR) [5-10]. Conventional unidirectional rolled Ta sheets suffered from uneven grain size distribution and texture clusters retained after annealing [7-9]. Texture gradients and residual deformation bands caused damage to the properties of the target material in UR annealed samples [9]. {100} and {111} were two main fiber textures obtained by UR, which displayed different subdivision behaviors and stored energy causing different recrystallization driving forces [1]. As revealed by Fan et al. [1], rapidly re-crystallized {111} grains and the {100} grains that exhibited essentially no microstructural changes at high temperatures were shown in the subsequent annealing process. Liu et al. [8] found that small orientation dependence and uniform storage energy distribution are shown in 135° CR samples.”

2 As Ta is a BCC material, consider using examples of other metals that are either BCC or that have high SFEs (like Ta) as a comparison.

RE: Thanks for the advice.

We have used examples of other metals that are either BCC or that have high SFEs  as a comparison， such as titanium (Ti), aluminum (Al), textured low alloy ferritic steel, tungsten (W) and aluminum alloys.

The text is revised as following.

• “At present, there was a vast body of experimental data showing that WR could be effectively employed to control the uniformity of microstructure and texture in titanium (Ti) [13], aluminum (Al) [14], textured low alloy ferritic steel [15], tungsten (W) [16] and aluminum alloys [17].” (line55)

Change to:

“At present, there was a vast body of experimental data showing that WR could be effectively employed to control the uniformity of microstructure and texture in titanium (Ti) [13], aluminum (Al) [14], textured low alloy ferritic steel [15], tungsten (W) [16] and aluminum alloys [17]. It was discussed by Murty et al. [18] that fine microstructure and high strength were obtained by WR in the Ti–6Al–4V bars. In addition, the fiber texture was weakened with increasing temperature and texture randomization was occurred during high-temperature deformation [18]. As WR temperature increased to 450 ℃ in pure Ti, Chun et al. [19] pointed out that recrystallization was produced more rapidly and the grain structure was refined in the recrystallized state. As revealed by Gatti [20], stronger cube textures after different annealing treatments were present in warmed rolled Al–2.5 wt.%Mg alloy in contrast to the cold rolled sample. With the amount of warm rolling deformation increases, dynamic recrystallisation was promoted and more sub-grains were found in the large 2219 Al–Cu alloy rings, as proposed by Guo [21]. Moreover, after solution heat treatment many finer and more equiaxed recrystallized grains were appeared, however, the uniformity of the grain structure is reduced [21]. According to the results reported by Li [16], the enhanced texture strength with the amount of deformation increasing was showed in the fine-grained tungsten.”

3. Provide some context for your results with respects to industrial needs. Even something as small as ‘reduction of dislocation content for performance enhancement’ is enough to help tie your results to the fundamental driver for your research.

RE: Thanks for the advice.

We have provided some context for our results with respects to industrial needs.

The text is revised as following.

• “In this paper a new rolling technology, WR (800 ℃) combined with 135°cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the micro-structure and texture evolution of Ta plates after deformation and annealing. In addition, WR at 500 ℃ was set as the control group.” (line78)

Change to:

“The research aim of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry. In this paper a new rolling technology, WR (800 ℃) combined with 135°cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the micro-structure and texture evolution of Ta plates after deformation and annealing. In addition, WR at 500 ℃ was set as the control group. The problem of nonuniformity of target sputtering coating caused by orientation dependence in traditional rolling processes has been effectively solved employing 135° warm cross rolling (WCR). This study will provide ideas for the development of optimized rolling processes for future industrial production.”

4. Re-construct your abstract to end with a larger conclusion.  The bits and pieces of conclusions sound unrelated and fail to provide a context for why this should be published.RE: Thanks for the advice.

We have re-construct our abstract to end with a larger conclusion. Why the background for publishing this article has been re-pointed out in the abstract. With advanced integrated circuits semiconductor chip, the uniformity of microstructure and texture is increasingly required for tantalum (Ta) target. This study will provide a theoretical reference for the precise optimization of tantalum process parameters and the improvement of target material performance.

The text is revised as following.

• “A combination of warm rolling and 135°cross rolling (CR) in the temperature of 500 ℃ and 800 ℃, i.e., warm cross rolling (WCR), was carried out in tantalum (Ta) plates to investigate the evolution of deformed microstructure and texture.” (line13)

Change to:

         “With advanced integrated circuits semiconductor chip, the uniformity of microstructure and texture is increasingly required for tantalum (Ta) target. A combination of warm rolling and 135°cross rolling (CR) in the temperature of 500 ℃ and 800 ℃, i.e., warm cross rolling (WCR), was carried out in tantalum (Ta) plates to investigate the evolution of deformed microstructure and texture”

• “Fine average grain size and high content of recrystallized grains with random orientation were obtained after annealing in the WCR sample.” (line23)
• Change to:

         “Fine average grain size and high content of recrystallized grains with random orientation were obtained after annealing in the WCR sample. This study will provide a theoretical reference for the precise optimization of tantalum process parameters and the improvement of target material performance.”

As I read through the paper, I struggled to determine how representative the results were that you shared.  This largely stems to the lack of clarity within the grain size measurements and the lack of labeling with respect to texture.

RE: Thanks for the advice.

In this article, a total of four rolling conditions were performed, and three samples were prepared under each condition. All samples were tested for orientation maps and texture maps, and the test results of the three samples are similar. The areas of the surface and central layers of the rolled samples tested for orientation maps are illustrated in figure 2. The orientation maps of samples under different conditions were tested in five areas to ensure the accuracy of the data. Extract the results of the grain size from the orientation maps of the three samples and calculate the average value. The parameters of vibration swing (Gamma width with 10 mm) were added during the XRD test to increase the test area. In addition, the surface area of the sample tested by XRD was about 10mm x 10mm. The results of ODF maps (section of φ₂ = 45°) in the article are representative, and the axes in the ODF maps have been marked in the revised version of the manuscript.

5. Figure 4 – why are pole figures included?  The ODFs provide the information that you compare against.  The pole figures seem superfluous.RE: Thanks for the advice.

The pole figures in figure 4 have been deleted.

The figure 4 is revised as following.

Figure 4. The pole figure distribution of initial sample along thickness and corresponding ODF section of φ₂ = 45°. Note S, Q and C represent the surface, quarter thickness and center layer, respectively.

Change to:

Figure 4. The corresponding ODF section of φ₂ = 45° in the initial sample along thickness. Note S, Q and C represent the surface, quarter thickness and center layer, respectively.

6. Line 126 – what is the angular resolution you used to define an orientation?  For instance, when I look at Figure 5 – the orientation information, I assume, is not a point in ODF space but rather a distribution.RE: Thanks for the advice.

The angular resolution we used to define an orientation is 10°. Figure 5 shows orientation information. Orientation information is a distribution. Here, we introduce four references as a support for defining an orientation. They pointed out that the defined orientation deviation is generally less than 20 °.

(1)Wang, X., Fan, F., Szpunar, J. A., & Zhang, L. (2015). Influence of grain orientation on the incipient oxidation behavior of Haynes 230 at 900 °C. Materials Characterization, 107, 33–42. doi:10.1016/j.matchar.2015.06.029

(2) Hou, N. X., Gou, W. X., Wen, Z. X., & Yue, Z. F. (2008). The influence of crystal orientations on fatigue life of single crystal cooled turbine blade. Materials Science and Engineering: A, 492(1-2), 413–418. doi:10.1016/j.msea.2008.03.043

(3) Esaka, H., Tamura, M., & Shinozuka, K. (2003). Analysis of Yield Rate in Single Crystal Casting Process Using an Engineering Simulation Model. MATERIALS TRANSACTIONS, 44(5), 829–835. doi:10.2320/matertrans.44.82910.2320/matertrans.44.829

7. Figure 5 – where was this data extracted from?  EBSD patterns?RE: Thanks for the advice.

The data extracted from EBSD patterns in orientation maps of initial Ta plates. We have also added data sources for Figure 5 to the article.

The text is revised as following.

• “Figure 5a,b are the grain size distribution of initial Ta plates and the average grain size corresponding to different crystal orientations, respectively.” (line144)

Change to:

         “Figure 5a,b are the grain size distribution of initial Ta plates and the average grain size corresponding to different crystal orientations, respectively. In addition, the data extracted from orientation maps of initial Ta plates.”

8. Figure 6 – largely unlabeled.  What are the axes?RE: Thanks for the advice.

We have added the axes in figure 6.

The figure 6 is revised as following.

Figure 6. The texture distribution of sample along the thickness processed by 800 ℃ warm uni-directional rolling (UR-800 ℃), cold 135° cross rolling (CR-20 ℃), 500 ℃ warm 135° cross rolling (CR-500 ℃) and 135° cross 800 ℃ warm rolling (CR-800 ℃).

Change to:

Figure 6. The texture distribution of sample along the thickness processed by 800 ℃ warm uni-directional rolling (UR-800 ℃), cold 135° cross rolling (CR-20 ℃), 500 ℃ warm 135° cross rolling (CR-500 ℃) and 135° cross 800 ℃ warm rolling (CR-800 ℃).

9. Figures 7 and 8 – shear bands were not clear.  Consider marking them within the images as it was difficult for me to see them in some of the images in Figure 7.RE: Thanks for the advice.

We have marked the location of the shear bands on figure 7 and figure 8.

The figure 7 is revised as following.

Figure 7. The ND orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Change to:

Figure 7. The ND orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

The figure 8 is revised as following.

Figure 8. The ND orientation maps of rolled Ta sheets in the center region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Figure 8. The ND orientation maps of rolled Ta sheets in the center region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

10. Figure 12 might be more effective as a table.  The plots seem to lose value above 20 degrees in misorientation angle.  Perhaps this can be improved for the reader’s sake.RE: Thanks for the advice.

The data in figure 12 has been changed to a table. The misorientation above 20 degrees has been deleted.

The figure 12 is revised as following.

Figure 12. The misorientation distribution of samples processed by (a)UR-800 ℃, (b)CR-20 ℃, (c) CR-500 ℃ and (d) CR-500 ℃.

Change to:

Table 2. The misorientation distribution of samples processed by UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-500 ℃.

11. Figure 13 – misspelled words are apparent in the y-axis descriptor for both a and b.  In addition, it is unclear why 10^5 was chosen when all the numbers are decimals.  Why not label 5 on figure 13a with the appropriate y-axis multiplier?RE: Thanks for the advice.

The misspelled words in the y-axis descriptor for both a and b have been changed. The appropriate y-axis multiplier (10^3) has been employed in figure 13.

The figure 13 is revised as following.

Figure 13. (a) The grain boundary energy distribution of sample processed by CR-20 ℃, CR-500 ℃ and CR-800 ℃; (b) the corresponding grain boundary energy for {100} and {111} textures of respective samples.

Change to:

Figure 12. (a) The grain boundary energy distribution of sample processed by CR-20 ℃, CR-500 ℃ and CR-800 ℃; (b) the corresponding grain boundary energy for {100} and {111} textures of respective samples.

12. Figure 14.  Earlier in Figure 5 you choose to not include boundary grains.  Here you seem to have quite a few.  How does that change your result?  And why did you make the decision to include them in Figure 14 and not in Figure 5?RE: Thanks for the advice.

Although figure 14 shows a map of recrystallized microstructure, boundary grains are not counted. The statistical diagram of grain size in figure 5 also does not include boundary grains. In order to observe the microstructure of initial recrystallization, the UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-800 ℃ samples are annealed at 1100 ℃ for 5 min, as shown in Figure 14. Figure 14 is mainly used to further study the grain orientation distribution of different samples at the early stage of recrystallization.

As I read through the discussion, I found a significant portion recreating textbook or other treatments of drivers for texture.  I found much of the discussion fairly rote and unimportant.  Do the results point to a fundamentally new understanding?  It does not appear that way.  Rather, these results are largely expected.  The discussion can be trimmed and literature utilized to indicate that results are as anticipated. 

RE: Thanks for the advice.

We have deleted some of the results from the discussion section. I have used the literature to show that the results are consistent with expectations.

13. Conclusions were largely supported by the data (except when the data was unclear as was pointed out earlier).  Point to explicit gaps in literature that these conclusions help fill.  In my survey of the literature you provided, there was little here that was fundamentally new, but you were ensuring that data was now being reported in open literature.RE: Thanks for the advice.

Unclear areas of the previously indicated data have been modified in the article. There is a lack of knowledge about the effect of WR process on microstructure uniformity carried out in Ta plates. This study will provide a theoretical reference for the precise optimization of tantalum process parameters and the improvement of target material performance. The research aim of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry. The problem of nonuniformity of target sputtering coating caused by orientation dependence in traditional rolling processes has been effectively solved through 135° warm cross rolling (WCR).

14. Conclusion #1 fails to point to friction between the rolling mill and the Ta material.  Was lubrication utilized in this study?  What if it had?  Consider extending some of your conclusions to point to future experimental needs.RE: Thanks for the advice.

Lubrication was not used in this study. Conclusion # 1 has pointed out the friction between the rolling mill and the Ta material. Prospects for future trials have been added to Conclusion 5 of the article. Using other rolling methods such as asymmetrical warm rolling, coupled with a better annealing system, to obtain tantalum plates with more uniform microstructure and texture.

The text is revised as following.

• “A strong shear texture (z fiber texture) is exhibited on the surface layer of the WCR sample due to the strong shear strain between the sample surface and the roll.” (line428)

Change to:

“A strong shear texture (z fiber texture) is exhibited on the surface layer of the WCR sample due to the friction between the sample surface and the roll.”

• “The CR-800 ℃ sample enjoys the smallest average grain size of 40.9 μm after annealing at 1050 ℃) for 60 min.” (line447)

Change to:

“The CR-800 ℃ sample enjoys the smallest average grain size of 40.9 μm after annealing at 1050 ℃) for 60 min. Future experiments can optimize the rolling temperature during warm cross rolling and use lubricants to achieve uniform microstructure of the sample along the thickness direction.”

 Shifeng Liu

[email protected]

Author Response File: Author Response.pdf

Reviewer 2 Report

The present manuscript deals with the investigation of tantalum after warm crossing rolling and after annealing. The manuscript is well written and contains detailed discussion of the presented results. However, some questions should be answered and some modifications made before it can be recommended for publication:

1. Line 191 vs line 203: The authors mention “complete recrystallization” after 1050°C 60 min and 1100°C 30 min. Later, a strong {100} texture band is discussed in the annealed-CR-20 ℃. It is confusing and should be clarified.

2. It is not clear how many images per sample were used for the statistics given in Fig. 11.

3. Although the recrystallized microstructure is expected in the whole sample volume, it should be mentioned in Figs. 9 and 10, which regions were investigated after annealing. Taking into account the observed region, it could contribute to the explanation of the texture band mentioned in the comment #1.

Besides the above given comments, some formal editing is mandatory:

- abbreviations should be introduced the first time a term is used – please check the whole manuscript

- the explanation of the directions (ND, RD, TD) could be possibly included in the Figure captions, where relevant

- Fig. 7 – legend with directions is hardly visible, the same is valid for the color legend; the color legend should be included in each image, where it is relevant

- 3.4 chapter title is the same as 3.3 ---> Recrystallization microstructure

- line 12: in the temperature ---> at the temperature

- line 31: target depend ---> target depends

- line 65: aim research ---> research aim

- line 68: references

Author Response

Dear editor,

The authors appreciate the helpful comments provided by reviewers. The revisions addressing the issues and comments are listed and explained below, in addition to those revisions and corrections from our own considerations. To facilitate the review process, response to each of the issues and comments is presented item by item and changes in the manuscript are highlighted in red.

Manuscript (No.: metals-2305866)

Reviewer#2:

1. Line 191 vs line 203: The authors mention “complete recrystallization” after 1050°C 60 min and 1100°C 30 min. Later, a strong {100} texture band is discussed in the annealed-CR-20 ℃. It is confusing and should be clarified.RE: Thanks for the advice.

Texture bands are also a form of completely recrystallized grains. The {100} texture band is just a region where 100 recrystallization aggregates.

2. In It is not clear how many images per sample were used for the statistics given in Fig. 11.RE: Thanks for the advice.

Each sample has five images for the statistics shown in figure 11. In the article, we also added that five regions were selected for statistical recrystallization grain size.

The text is revised as following.

• “Figure 11 displays the average grain size distribution and the volume fraction of {111}, {110}, {100} and randomly oriented grains for corresponding samples after complete annealing at 1050 ℃ for 60 min and 1100 ℃ for 30 min.” (line214)

Change to:

“Figure 11 displays the average grain size distribution and the volume fraction of {111}, {110}, {100} and randomly oriented grains for corresponding samples after complete annealing at 1050 ℃ for 60 min and 1100 ℃ for 30 min. Five regions of each annealed samples are selected for statistical recrystallization grain size.”

3. Although the recrystallized microstructure is expected in the whole sample volume, it should be mentioned in Figs. 9 and 10, which regions were investigated after annealing. Taking into account the observed region, it could contribute to the explanation of the texture band mentioned in the comment #1. Besides the above given comments, some formal editing is mandatory:- abbreviations should be introduced the first time a term is used – please check the whole manuscript- the explanation of the directions (ND, RD, TD) could be possibly included in the Figure captions, where relevant- Fig. 7 – legend with directions is hardly visible, the same is valid for the color legend; the color legend should be included in each image, where it is relevant- 3.4 chapter title is the same as 3.3 ---> Recrystallization microstructure- line 12: in the temperature ---> at the temperature- line 31: target depend ---> target depends- line 65: aim research ---> research aim- line 68: referencesRE: Thanks for the advice.

(1) The study area for all annealed samples is explained in the figure notes relating to figures 9 and 10. The central area of each annealed sample is the study area for microstructure.

(2) I have checked the whole manuscript and all abbreviations have been written in full when they first appeared.

(3) The explanation of the directions (ND, RD, TD) has been possibly included in the Figure captions, where relevant.

(4) The legend with direction and color in figure 7 have been changed. The color legend has been included in each associated map.

(5) The 3.4 chapter title has been changed to “microstructure after annealing”

(6) We have changed " in the temperature " to " at the temperature ".

(7) We have changed " target depend " to " target depends ".

(8) We have changed " aim research " to " research aim ".

(9) The “references” in line 68 has been deleted.

The text is revised as following.

• “The recrystallization microstructure evolution of samples annealed at 1050 ℃ and 1100 ℃ for different times respectively are shown in Figure 9 and Figure 10.” (line205)

Change to:

“The recrystallization microstructure evolution of samples annealed at 1050 ℃ and 1100 ℃ for different times respectively are shown in Figure 9 and Figure 10.” The central area of each annealed sample is the study area for microstructure.”

• “Figure 7. The orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.” (line198)

Change to:

“Figure 7. The normal direction (ND) orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.”

• “3.4. Deformation microstructure” (line203)

Change to:

“3.4. Microstructure after annealing”

• “A combination of warm rolling and 135° cross rolling (CR) in the temperature of 500 ℃ and 800 ℃, i.e., warm cross rolling (WCR), was carried out in tantalum (Ta) plates to investigate the evolution of deformed microstructure and texture.” (line14)

Change to:

“A combination of warm rolling and 135° cross rolling (CR) at the temperature of 500 ℃ and 800 ℃, i.e., warm cross rolling (WCR), was carried out in tantalum (Ta) plates to investigate the evolution of deformed microstructure and texture.”

• “Thus, the Ta target with excellent performance depend on the uniformity of microstructure and texture [1-4].” (line35)

Change to:

“Thus, the Ta target with excellent performance depends on the uniformity of microstructure and texture [1-4].”

• “The aim research of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry.” (line75)

Change to:

“The research aim of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry.”

The figures are revised as following.

Figure 7. The ND orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Change to:

Figure 7. The normal direction (ND) orientation maps of rolled Ta sheets near the surface region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Figure 8. The ND orientation maps of rolled Ta sheets in the center region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Change to:

Figure 8. The normal direction (ND) orientation maps of rolled Ta sheets in the center region processed by (a) UR-800 ℃, (b) CR-20 ℃, (c) CR-500 ℃ and (d) CR-800 ℃.

Figure 9. The recrystallized microstructure evolution of UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-800 ℃ samples annealed at 1050 ℃ for 60 min, 90 min and 120 min.

Change to:

Figure 9. The recrystallized microstructure evolution of UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-800 ℃ samples annealed at 1050 ℃ for 60 min, 90 min and 120 min.

Figure 10. The recrystallized microstructure evolution of UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-800 ℃ samples annealed at 1100 ℃ for 30 min and 60 min.

Change to:

Figure 10. The recrystallized microstructure evolution of UR-800 ℃, CR-20 ℃, CR-500 ℃ and CR-800 ℃ samples annealed at 1100 ℃ for 30 min and 60 min.

Shifeng Liu

[email protected]

Author Response File: Author Response.pdf

Reviewer 3 Report

The article submitted for review is very interesting and in my opinion does not require necessary changes, only possible corrections. The authors could include a few photos from real tests next to the diagrams and expand the description of the equipment used for the tests. In addition, I would put the Objectives of the article on a separate line (line 62). For clarification, please provide extended bases of temperature selection for the deformation process. Was the strain applied in one or more sequences? How reheating in the furnace (authors' opinion) can affect the structural changes of the tested Ta.

Author Response

Dear editor,

The authors appreciate the helpful comments provided by reviewers. The revisions addressing the issues and comments are listed and explained below, in addition to those revisions and corrections from our own considerations. To facilitate the review process, response to each of the issues and comments is presented item by item and changes in the manuscript are highlighted in red.

Manuscript (No.: metals-2305866)

Reviewer#3:

1. The article submitted for review is very interesting and in my opinion does not require necessary changes, only possible corrections. The authors could include a few photos from real tests next to the diagrams and expand the description of the equipment used for the tests. In addition, I would put the Objectives of the article on a separate line (line 62). For clarification, please provide extended bases of temperature selection for the deformation process. Was the strain applied in one or more sequences? How reheating in the furnace (authors' opinion) can affect the structural changes of the tested Ta.RE: Thanks for the advice.

(1) We have expanded the description of the equipment used for the tests.

(2) We have put the objectives of the article on a separate line (line 75)

(3) We have provided extended bases of temperature selection for the deformation process. Ta releases most of its storage energy during the recovery, even up to 70%, which is attributed to its high SFE leading to easy dislocation climbing and cross-slip migration. Moreover, the recovery has a pronounced impact on recrystallization behavior of Ta. 800 ℃, the recovery temperature of tantalum, was determined to be the WR temperature based on the differential scanning calorimetry (DSC) experimental curve. In addition, WR at 500 ℃ was set as the control group.

(4) The strain per pass is the thickness reduction per pass divided by the thickness before each pass. We have rolled a total of 12 passes, and the magnitude of the strain per pass is controlled to be between 2.43 and 3.39 by controlling the value of l/h. The deformation geometric parameter l/h can make the plate uniformly deformed during the rolling process. The value of deformation zone parameter l/h (l is the projected length of contact between the rolls and specimen, and h is the average thickness of the sample before and after rolling) for each rolling pass was set between 2.43 and 3.39, which is considered to guarantee a plane-strain state.

(5) 800 ℃ is the recovery temperature of tantalum. 500 ℃ is lower than the recovery temperature of tantalum. In addition, in the warm rolling process, it takes relatively short time for the tantalum plate to be rolled eight times before being put into the furnace for reheating. Reheating the tantalum plate at 500℃ has no effect on the structure. Although reheating the tantalum plate at 800 ℃ has an impact on the structure, the impact is very small.

The text is revised as following.

• “The microstructure measurements were characterized at surface and center regions of the transverse direction (TD) plane (Figure 2), with the EBSD system mounted on a TESCAN MIRA 3 field-emission scanning electron microscope (accelerating voltage of 20 kV and working distance of about 15 mm).” (line109)

Change to:

“The microstructure measurements were characterized at surface and center regions of the transverse direction (TD) plane (Figure 2), with the EBSD system mounted on a TESCAN MIRA 3 field-emission scanning electron microscope (accelerating voltage of 20 kV and working distance of about 15 mm). During the test, the incident electron beam interacts with a 70° tilted surface area of the sample to obtain information on the daisy pool pattern of the test area, which is processed into orientation information. Steps for recrystallized samples are 1-3 μm and the step size of the deformed sample is 0.05-1 μm. The orientation maps of samples under different conditions were tested in five areas to ensure the accuracy of the data.”

• “The XRD inspection surface was at the surface, quarter and center layer of normal direction (ND) surface, as shown in Figure 2.” (line109)

Change to:

“The XRD inspection surface was at the surface, quarter and center layer of normal direction (ND) surface with an area of 10×10mm², as shown in Figure 2. During the measurement, the detection area was 20-90° for α and 0-360° for β. Four in-complete pole figures of {222}, {211}, {200} and {110} were measured using the Schulz re-flection method.”

• “In this paper a new rolling technology, WR (800 ℃) combined with 135° cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the microstructure and texture evolution of Ta plates after deformation and annealing.” (line77)

Change to:

“The research aim of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry. In this paper a new rolling technology, WR (800 ℃) combined with 135° cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the microstructure and texture evolution of Ta plates after deformation and annealing.”

Shifeng Liu

[email protected]

Author Response File: Author Response.pdf

Reviewer 4 Report

The paper is devoted to the study of the effect of warm 135° cross rolling on the microstructure and texture of high-purity tantalum. Some remarks can be made:

1. The initial thickness of the samples (before rolling) and thickness reduction per pass must be specified.

2. The rolling direction is rotated by 135° around normal direction sequentially, and one processing cycle consists of eight passes in 135° cross rolling. What are the geometric constraints of this process? Sheet width in unidirectional rolling is limited by the length of the working roll barrel. And with a 135° cross rolling, not only the width, but also the length of the sheet will also be limited by the length of the barrel of the work roll. How do the maximum width and length of the sheet depend on the length of the barrel of the work roll during 135° cross rolling? What length of the samples was obtained in the experiments after 135° cross rolling? How was it possible to maintain an angle of 135° in each pass during cross rolling?

3. The conclusion states that a strong shear texture is exhibited on the surface layer of the WCR sample due to the strong shear strain between the sample surface and the roll. What causes this shear strain? Is this shear strain only due to the high contact friction between the surface layer of the WCR sample and the roll, or is it due to the continuous change of strain paths in 135° warm cross rolling?

4. The conclusion states that the CR-800 °C sample enjoys the smallest average grain size of 40.9 μm after annealing at 1050 °C for 60 min. But what is the target level for average grain size?

5. It is also necessary to clearly formulate the scientific novelty of the article.

Author Response

Dear editor,

The authors appreciate the helpful comments provided by reviewers. The revisions addressing the issues and comments are listed and explained below, in addition to those revisions and corrections from our own considerations. To facilitate the review process, response to each of the issues and comments is presented item by item and changes in the manuscript are highlighted in red.

Manuscript (No.: metals-2305866)

Reviewer#4:

1. The initial thickness of the samples (before rolling) and thickness reduction per pass must be specified.RE: Thanks for the advice.

We have added in the article that the initial thickness of the tantalum plate is 12 mm. Details of the reduction in thickness for each process have been detailed in the cited reference 7 and 23. We have also added the table 1 on rolling procedures to the article.

The text is revised as following.

• “The Ta plates were rolled via UR at 800 ℃ and CR at three different temperatures of 20 ℃, 500 ℃ and 800 ℃ (70% thickness reduction), which were described as UR-800 ℃, CR-20 ℃, CR-500 ℃, CR-800 ℃ samples.” (line89)

Change to:

“The Ta plates with 12 mm thickness were rolled via UR at 800 ℃ and CR at three different temperatures of 20 ℃, 500 ℃ and 800 ℃ (70% thickness reduction), which were described as UR-800 ℃, CR-20 ℃, CR-500 ℃, CR-800 ℃ samples.”

The table 1 is revised as following.

• “Figure 1. Schematic diagrams of the UR and CR in Ta.” (line103)

Change to:

Table 1. Rolling scheme of UR and CR.

2. The rolling direction is rotated by 135° around normal direction sequentially, and one processing cycle consists of eight passes in 135° cross rolling. What are the geometric constraints of this process? Sheet width in unidirectional rolling is limited by the length of the working roll barrel. And with a 135° cross rolling, not only the width, but also the length of the sheet will also be limited by the length of the barrel of the work roll. How do the maximum width and length of the sheet depend on the length of the barrel of the work roll during 135° cross rolling? What length of the samples was obtained in the experiments after 135° cross rolling? How was it possible to maintain an angle of 135° in each pass during cross rolling?RE: Thanks for the advice.

The geometric constraint is that there is a formula for l/h which is also described in detail in reference 23. with a 135° cross rolling, not only the width, but also the length of the sheet will also be limited by the length of the barrel of the work roll. The original 135° cross-rolled tantalum plates are cylindrical with a height of 12 mm and a diameter of 8 cm. The diameter of the rolling mill is 100 cm. The diameter and thickness of the original tantalum plate are much smaller than the diameter of the rolling mill. The length of the work roll is very long, and it is not necessary to consider that the width and length of the plate will be limited by the length of the work roll. The length of tantalum plate after 135° cross rolling is 15 cm. We use multiple tools such as a marker and a square to confirm the angle of 135° to ensure that each rolling process maintains a 135°.

3. The conclusion states that a strong shear texture is exhibited on the surface layer of the WCR sample due to the strong shear strain between the sample surface and the roll. What causes this shear strain? Is this shear strain only due to the high contact friction between the surface layer of the WCR sample and the roll, or is it due to the continuous change of strain paths in 135° warm cross rolling?RE: Thanks for the advice.

In all, the shear strain is exhibited on the surface layer of the WCR sample due to the sample subjected to ND and RD directional forces. The shear strain is exhibited on the surface layer of the WCR sample due to the high contact friction between the surface layer of the WCR sample and the roll and the continuous change of strain paths in 135° warm cross rolling.

4. The conclusion states that the CR-800 °C sample enjoys the smallest average grain size of 40.9 μm after annealing at 1050 °C for 60 min. But what is the target level for average grain size?RE: Thanks for the advice.

The target level for average grain size is less than 100 μm.

5. It is also necessary to clearly formulate the scientific novelty of the article.RE: Thanks for the advice.

We have clearly stated the scientific novelty of the article.

The text is revised as following.

• “In this paper a new rolling technology, WR (800 ℃) combined with 135°cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the micro-structure and texture evolution of Ta plates after deformation and annealing. In addition, WR at 500 ℃ was set as the control group.” (line78)

Change to:

“The research aim of processing Ta plates under warm rolling conditions is to further improve sputtering performance of Ta targets and contribute to the development of integrated semiconductor industry. In this paper a new rolling technology, WR (800 ℃) combined with 135°cross rolling (CR) and unidirectional rolling (UR) respectively, was applied to investigate the microstructure and texture evolution of Ta plates after deformation and annealing. In addition, WR at 500 ℃ was set as the control group. The problem of nonuniformity of target sputtering coating caused by orientation dependence in traditional rolling processes has been effectively solved employing 135° warm cross rolling (WCR). This study will provide ideas for the development of optimized rolling processes for future industrial production.”

Shifeng Liu

[email protected]

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you very much for the improvements to the manuscript.  The technological pull with respect to targets helps me to understand the purpose of the paper and research.  It also indicates exactly why this is important to publish as the scientific results are rather uninteresting on their own.

I would ask that you improve the grammar in the correction you made in lines 148 and 149.  Also, I would ask that you provide an indication of your the angle that represented an orientation in the text of your paper in the methodology section.  Your response to my question was sound, but the inclusion in the revised manuscript is mandatory.

Author Response

Dear editor,

The authors appreciate the helpful comments provided by reviewers. The revisions addressing the issues and comments are listed and explained below, in addition to those revisions and corrections from our own considerations. To facilitate the review process, response to each of the issues and comments is presented item by item and changes in the manuscript are highlighted in red.

Manuscript (No.: metals-2305866)

Reviewer#1:

1 Thank you very much for the improvements to the manuscript.  The technological pull with respect to targets helps me to understand the purpose of the paper and research.  It also indicates exactly why this is important to publish as the scientific results are rather uninteresting on their own.

I would ask that you improve the grammar in the correction you made in lines 148 and 149.  Also, I would ask that you provide an indication of your the angle that represented an orientation in the text of your paper in the methodology section.  Your response to my question was sound, but the inclusion in the revised manuscript is mandatory.

RE: Thanks for the advice.                                        

1) The grammar on lines 148 and 149 has been changed.

2) We have provided an indication of  the angle that represented an orientation in the methodology section of the paper.

3) All questions in the reply have been changed in the manuscript. Regarding the 13th review comment from the previous review, it has been revised in the abstract, introduction, and conclusion section of the article

The text is revised as following.

• “Figure 5a,b are the grain size distribution of initial Ta plates and the average grain size corresponding to different crystal orientations, respectively.” (line153)

Change to:

“Figure 5a,b are the grain size distribution of initial Ta plates and the average grain size corresponding to different crystal orientations, respectively. In addition, the data is extracted from orientation maps of initial Ta plates. The angular resolution used to define an orientation is 10°.”

• “The arbitrarily defined cells (ADC) method was adopted to calculate orientation distribution functions (ODFs).” (line129)

Change to:

“The arbitrarily defined cells (ADC) method was adopted to calculate orientation distribution functions (ODFs). The typical textures in Ta are α, γ, θ and z fiber textures. The Euler angles of these fiber textures are (0°,90°,45°), (90°,55°,45°), (0°,45°,45°) and (90°,45°,0°), respectively.”

• “The Ta plates with 12 mm thickness were rolled via UR at 800 ℃ and CR at three different temperatures of 20 ℃, 500 ℃ and 800 ℃ (70% thickness reduction), which were described as UR-800 ℃, CR-20 ℃, CR-500 ℃, CR-800 ℃ samples.” (line91)

Change to:

“The Ta plates with 12 mm thickness were rolled via UR at 800 ℃ and CR at three different temperatures of 20 ℃, 500 ℃ and 800 ℃ (70% thickness reduction), which were described as UR-800 ℃, CR-20 ℃, CR-500 ℃, CR-800 ℃ samples. Three samples were prepared for characterization testing under each rolling condition.”

• “Steps for recrystallized samples are 1-3 μm and the step size of the deformed sample is 0.05-1 μm.” (line117)

Change to:

“Steps for recrystallized samples are 1-3 μm and the step size of the deformed sample is 0.05-1 μm. The orientation maps of samples under different conditions were tested in five areas to ensure the accuracy of the data.”

• “The XRD inspection surface was at the surface, quarter and center layer of normal direction (ND) surface, as shown in Figure 2.” (line124)

Change to:

“The XRD inspection surface was at the surface, quarter and center layer of normal direction (ND) surface an area of 10×10mm², as shown in Figure 2. The parameters of vibration swing (Gamma width with 10 mm) were added during the XRD test to increase the test area.”

• “By comparison, it is found that complete recrystallization is occurred in samples annealed at 1050 ℃ for 60 min and 1100 ℃ for 30 min.” (line226)

Change to:

“By comparison, it is found that complete recrystallization is occurred in samples annealed at 1050 ℃ for 60 min and 1100 ℃ for 30 min. Five regions of each annealed samples are selected for statistical recrystallization grain size.”

Shifeng Liu

[email protected]

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors reflected all comments to the revised manuscript, therefore I can recommend it for publication.

Author Response

Thank you very much for your guidance on the article.

Author Response File: Author Response.pdf

Reviewer 4 Report

The authors have improved the article taking into account my comments.

Author Response

Thank you very much for your guidance on the article.

Author Response File: Author Response.pdf