Effects of Cold Rolling Deformation and Solution Treatment on Microstructural, Mechanical, and Corrosion Properties of a Biocompatible Ti-Nb-Ta-Zr Alloy

Round 1

Reviewer 1 Report

This paper contain the interesting experiments about the effects of cold rolling deformation and solution treatment on microstructural, mechanical and corrosion properties of TNTZ alloy.

However, there is not enough expression of figures or texts and explanation of the results, so it is better to improve this paper.

Specific comments.

Please review the wards and the space position between words once again.

For example, schemeto(L.31),　anyield(l.35), beassesed(l.308), grain-zize(l.238), and so on.

As for Figure 3.

The scale and characters in the figure are too small to read, so please revise them.

In Fig.3 (b), light and shade areas are seen especially in red, green, and light blue. Please explain the idea that they are homogenized.

As for Figure 6.

Is this photo the microstructure of the cross section observed as it is? Or is it the etched microstructure?

Please distinguish which part of this photo corresponds to the deformation band, deformation twin, and dislocation band.

3.4 Corrosion testing of TNTZ alloy in SBF

Please explain whether the data shown in Table 8 is a dominant difference or a margin of error, including microstructural views.

For example, from ST2.1 to ST2.4, if it is a linear change, it is considered to be related to the increase of the grain size. However, if the increase and decrease occur alternately, it is considered to be within the margin of error.

Author Response

Dear reviewer, I wanna thank for your remarks and I apologize for delayed responses. Please see in the attachment some of the response to you comments.

Unfortunately due to the winter holidays some of our colleagues who worked on this article could not be found, to be able to fully respond to your comments. We will return as soon as possible with the final completion.

Author Response File: Author Response.pdf

Reviewer 2 Report

I have the following comments to this manuscript. Major revision is suggested before it can be re-evaluated for publication.

• Abstract: By applying this TMP scheme, the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy showed an elastic modulus of 56 GPa,…. Please provide the full name in the abstract when an abbreviation is used.

• Introduction: It is suggested more relevant references are cited and recent research progress is summarized to support the aim of your research.

• Figure 1. The duration for the solution treatment for ST1.3 is the same as ST1.4, i.e. 15 min, so are the ST2.4 and ST3.4. Please double check.

• Figure 2. Do you have a specific value of R1?

• Figure 3. The quality of the image should be improved.

• Figure 6. We can see several cracks at the specimen surface. Does this mean the ductility of the material is not good?

• In table 4, are given the grain-size evolutions of the TNTZ alloy microstructure during ST treatment performed at different temperatures (800 °C, 900 °C and 1000 °C respectively) and different holting times (5 min, 10 min, 15 min and 20 min respectively). Please revise the sentence. “holting times”?

• “During solution treatment the most influential factor on grain-size is the heating temperature, because for 20 min treatment duration the grain-size is increasing from 62 μm at 800 °C, to 79 μm at 800 °C, and to 162μm at 1000 °C”. 79 μm at 800 °C?

• All previous presented micrographs, where the TNTZ alloy microstructure it can be seen and analyze the evolution of grain-size can be well correlated with the graphical representation presented bellow. Bellow?

• 10. Range marks are required if you could.

• Figure 11. Polarization tests are generally performed under a relatively stable condition. From Fig. 11a, the OCP is rising with time suggesting the testing system is not stabilized? What do you think?

• It can be considered that the more electropositive values of the open circuit potential (EOC) denote a more noble character from the electrochemical point of view. Thus, the ST 2.3 sample, having the most electropositive value (-280 mV), has a better corrosion behaviour than the other samples, being closely followed by the AR (-281 mV) and ST 2.4 (-282 mV) samples. However, based on the polarization analysis, you claim that that the CR sample has the best corrosion resistance as compared to the rest samples. Are they contradictory? Please give some explanation.

• Also, from the polarization curves, it seems the ST 2.1 sample shows the worst corrosion resistance since it has the lowest Ecorr and the lowest potential for Epitting or film rupture. Is this true?

• More discussion is required in the Results and Discussion section, otherwise it is a report rather than a scientific paper.

• The required corrosion resistance or corrosion rate as implant material for medical applications should be provided and compared with the ones reported in this work, which could be a strong evidence showing the developed materials are potential candidates.

• Rp (kΩxcm2): it is informal to use the unit like this.

• Line 295:toassess; line 308: beassesed.

Author Response

Dear reviewer, I wanna thank for your remarks and I apologize for delayed responses. Please see in the attachment some of the response to you comments.

Unfortunately due to the winter holidays some of our colleagues who worked on this article could not be found, to be able to fully respond to your comments. We will return as soon as possible with the final completion.

Author Response File: Author Response.pdf

Reviewer 3 Report

Abstract：

1. Line 33, page 1: the first occurrence of TMP in the abstract should not be abbreviated.
2. Line 35, page 1: it should be “an yield” instead of “anyield”.
3. It can be seen that the author has done relevant experimental research in this work, including mechanical performance testing and corrosion testing. It is recommended that the authors quantify the improved comprehensive properties of the alloy in the abstract, including mechanical properties and corrosion resistance.
4. It seems that the author’s keywords are inappropriate. Keywords should include the main direction in this work, not the method of characterization, such as “xxx testing”, “xxx testing”.

Text:

1. Line 71, page 2: please unify “Ti-25.5Nb-4.5Ta-8.0Zr (wt%)” and “Ti-25.5Nb-4.5Ta-8.0Zr wt%” in line 20, page 1.
2. Figure 2 should mark the unit.
3. It is difficult to distinguish the types of alloying elements in Figures 3b and 3c.
4. Please keep the same type of dimension for all light microscope figures in the text.
5. The scales of abscissa and ordinate in Figure 5 are not clear.
6. Please keep the same drawing methods for all graphs in the text. Please refer to the latest format requirements of the journal or published articles.
7. Line 310, page 10: The formula should have a number.
8. Similarly, in the conclusion section, please summarize the main conclusions of this work, and quantify the main data, rather than qualitatively describe.

Author Response

Dear reviewer, I wanna thank for your remarks and I apologize for delayed responses. Please see in the attachment the response to you comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Please reconsider the following points.

Point 3: In Fig.3 (b), light and shade areas are seen especially in red, green, and light blue. Please explain the idea that they are homogenized.

Response 3: as respects Fig.3 (b), it was specified in the text (L 161-162) that all alloying elements presented a good chemical homogeneity in the as-received TNTZ alloy.

Comment: Although there is a distribution of shades in the distribution results, is it a slight difference? If so, I think it would be less misleading to use only the text without showing the distribution results or add appropriate description.

Point 4: As for Figure 6. Is this photo the microstructure of the cross section observed as it is? Or is it the etched microstructure? Please distinguish which part of this photo corresponds to the deformation band, deformation twin, and dislocation band.

Response 4: -

Comment: This photo appears to be a cross-sectional structure rather than a surface structure. I understand the formation of the deformation band, but I think it is better to add what is judged to be the deformation twin, and dislocation band. Or to make it only the deformation band.

Author Response

Dear reviewer, thank you again for your remarks and I apologize once again for delayed responses. Please see in the attachment responses to you comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Since some of the questions were not addressed due to the winter holidays, I suggest a further review could be made when these questions are answered. I also add additional comments for your consideration.

1. It is suggested the revised sites are highlighted so that the editors and reviewers could easily identify them. For instance, the revised sites for the point 2 “Introduction: It is suggested more relevant references are cited and recent research progress is summarized to support the aim of your research” could be highlighted.

2. Figure 2. Do you have a specific value of R1?

3. Figure 6. We can see several cracks at the specimen surface. Does this mean the ductility of the material is not good?

4. 10. Range marks are required if you could.

5. More discussion is required in the Results and Discussion section, otherwise it is a report rather than a scientific paper. For this question, please highlight where the revisions were made, which could be more convenience for the review.

6. The required corrosion resistance or corrosion rate as implant material for medical applications should be provided and compared with the ones reported in this work, which could be a strong evidence showing the developed materials are potential candidates. Even though you have provided a sentence to the manuscript “Nevertheless, similar results of the corrosion parameters have also been reported by Surmeneva, M. et al [26] which have developed a TNTZ alloy by electron beam melting technique”, the reviewer still want to know if there are recommended/suggested/required corrosion resistance or corrosion rate as implant material for medical applications? It is useful and interesting information to the readers.

Author Response

Dear reviewer, thank you again for your remarks and I apologize once again for delayed responses. Please see in the attachment the responses to you comments.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Thank you for your responses, my comments are listed below.

“Q: Figure 10. Range marks are required if you could. Response 4: I'm not sure what do you mean by range marks. Can you give me an example? Maybe will be useful for me into the future.” In figure 10, you could add error bars if you run parallel tests and obtained standard deviation of the measured data. If you did, the method for the grain size measurement should be provided. Is that the same method for the Figure 5?

“To be used as implant material for medical applications, according to the literature [47,48,49], the required corrosion rate of the titanium base alloys is usually smaller than 0.02 mm/y and and not biger than 0.13 mm/y, value that is considered to be the maximum corrosion rate usually accepted for implantable metallic biomaterials”. In this sentences, “and and”, ”biger than”, and “usually accepted” may be revised.

Author Response

Dear reviewer, please see in the attachment the responses to you comments.

Author Response File: Author Response.pdf