Microstructure Change, Nano-Hardness and Surface Modification of CN-G01 Beryllium Induced by Helium Ions
Round 1
Reviewer 1 Report
Dear editors, the reviewed article is interesting for the reader, discreet and does not contain obvious weaknesses. It is recommended to accept it for publication without the need for revision.
Author Response
No reply is required.
Reviewer 2 Report
It is an article that presents many results on the implantation of helium in Beryllium (I admit that I don't know very well the bibliography on this metal). There are interesting results especially the pictures by TEM.
The article is however a bit long and confusing, especially the first part on SEM observations. Writing it in a simpler way would increase understanding.
3.1
· it is very difficult to discuss the figures 2 where I admit I don't see much - the scales are so small (and when the figures will be reduced it will be worse) - And what to notice? For me the differences are not so obvious (or significant: line 136) - put arrows on what we have to see! (we don't have to believe you) – Please better guide the reader - and what do we see in the middle (and below) of figure 2 b (this is confusing) when no change should be observed (written line 135)?
· Fig. 3 and comments: first pay attention to the scale in ordinates Freq (%)? data have been fitted by a Gaussian law giving the average size (15µm line 139 and the straggling s ?) and compare with 1018 ion/cm2? So, in (d) these are blisters - their distribution does not seem at all uniform - Rewrite the legend (b) because there is no nano-blister at 1018 cm-2.
· “When increasing fluences to 1×1018 ions/cm2, nano-sized blisters disappear as shown in Fig. 2(e).” line 146-147 –what do we see at the bottom of the image? is it the density of the nanoblister that drops drastically? and can we estimate it?
Actually all scales should be more clearly identified SEM, TEM (figure 6), ..
· Line 155: What do you means by “surface conditions”? I am not very satisfied with the following explanation - the implantation is at 900µm deep
3.2
· Line 212 : with increasing fluence the width increases, OK – but the swelling should also increase with fluences, that should lead to the deeper formation of the damaged area – right? it is not very clear by the given values (line 209)
· I am surprised that bubbles are observed on the whole area implanted at 1018 (figure 7) because it was not the case in the previous discussion?
· I enjoy the TEM pictures but please the scale !!
Author Response
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Author Response.pdf
Reviewer 3 Report
In this manuscript the authors have studied the effect of helium-ions irradiation on the beryllium (grade CN-G01). The results are interesting and worth publishing, although I suggest the authors to make several changes before publishing:
1. The introduction should be modified to make easier to read. There are some very long sentences.
2. He concentration: appm (atomic parts per million) and Dpa: displacement per atom, should be defined in the introduction.
3. In the introduction, may be worth also include the behaviour of bubble formation in other materials after irradiation with He-ions. For example: https://doi.org/10.1016/j.jnucmat.2017.08.033
4. Introduction, line 59-60: please provide reference(s).
5. In the text you mention several times “low temperature” (for example, but not only, in pages 2 and 10). What are the temperature values (or range of values) you call low and high temperatures? Why do you have only studied the effect of irradiation at low temperatures?
6. Numbers written in figure 4b are not visible.
7. Page 4 (line: 148-): In this discussion is not clear what is the effect of surface condition (mechanical vs chemical) and the effect of He concentration. Please rewrite and give the He concentration of ref 18 for better comparison with your results.
8. In page 4 (line 179) you concluded that “Therefore, it is better that the accumulated He concentration is below about 29.3% at any temperatures for the use of CN-G01 beryllium.”. I understand that this is because you observe blistering for fluence values of 5x10^17 but not for 1x10^17 ions/cm^2. Nevertheless, the difference between helium concentration values for these conditions (29.3% and 5.85%, respectively) is too large to draw this conclusion. You don’t know what happens between 5.85% and 29.3%. This part should be rewrite to make this clearer.
9. Page 6, line 200: “It indicates that the threshold He fluence for helium bubble formation is 1.0×10^17 ions/cm^2…”. The same comment as before. From your results you know that the threshold for helium bubble formation is between 5x10^16 and 1x10^17 ions/cm^2.
10. Figure 5: Please provide explanation of difference between b and b’ and between c and c’ in the caption (not only in the text). Also be aware that in (a) “500 nm” is partially hidden by the red line, please correct. Why do you use the same area (red rectangle) for all cases when in the text you report differences between the damage section in the three shown cases (lines 208-210, page 7)?
11. Page 10, line 264: Tm is not defined.
12. Figure 8, page 11, line 326: The behaviour of as-received sample also shows what you called in the text “bilinear relation”. The linear fit is not good for 1/d larger than about 0.03 1/nm, where a constant trend is observed.
13. Conclusions: In the introduction you mentioned some differences observed between different beryllium grades. It is not clear after reading the paper what are the differences you observe in this study (compared to other studies), and if the differences could be due to the different material grade or to other parameters (such as surface preparation, temperature of irradiation, etc).
Author Response
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Reviewer 4 Report
In this work, authors have studied the effect of He implantation on the microstructure and hardness of CN_G01 beryllium. Although the authors have adopted SEM, TEM and NIT to show the results, but its not new to the scientific community. Surface hardening due to ion irradiation is a very common phenomenon. It would be appealing if the authors can study the cross-section of the irradiated sample and can show He bubble penetration depth, internal crack mechanism and microstructure. There are some typo errors in the manuscript.
Author Response
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Round 2
Reviewer 4 Report
The authors have improved the manuscript as per the suggestions.
