Effect of Eutectic Mg2Si Phase Modification on the Mechanical Properties of Al-8Zn-6Si-4Mg-2Cu Cast Alloy
Round 1
Reviewer 1 Report
Please consider the following.
With regarding to alloy name of the title, I think that Al-8Zn-6Si-4Mg-2Cu 'cast' alloy looks to be better than Al-8Zn-6Si-4Mg-2Cu alloy.
Please revise superscript at lines from 35 to 36.
There was no description about Al-8Zn-6Si-4Mg-2Cu alloys. You should mention the reason why had you investigate Mg2Si phase in Al-8Zn-6Si-4Mg-2Cu alloy.
Please mention atmosphere during melting in experimental method.
How did you degas before casting? Please mention degassing method.
Please mention the size of y-block mold as readers can imagine an ingot size.
Please mention from where did you cut off tensile specimens shown in Fig. 1 in ingots. The microstructures may depend on sampling places of the ingots.
No calculation method about Table 2 was found in the text. You should explain How to calculate, because no one can confirm validity.
Is Fig. 2 also delivered by calculation? experimental results? Please make clear.
Is the unit of vertical axis in Fig. 2 percent? 1% in total?
In the calculation about Table 2 and Fig. 2, did you consider the main additive element of 8%Zn? And also did you take into account 2%Cu? Explanation is necessary.
I think that Q-phase is unclear because the meaning of Q-phase would change depending on alloy system.
'C' of Fig. 3 seems to be Si-particle.
Are there no segregation of Zn and no formation of Zn compounds?
From line 108 to line 111, 'Fig. 2' should be 'Fig. 3'.
At line 111, description of 'theta phase' would be open to misunderstanding, since Al2Cu phase is not always 'theta phase' while it is 'theta phase' in Al-Cu alloy system phase diagram.
With regard to Fig. 4, why refinement of primary alpha-phase (dendrite) did not occur by adding Al-5Ti-1B? Al-5Ti-1B has utilized as the Al-phase refiner for making aluminum alloy slabs in industry production.
Are the average values of the tensile test shown in Fig. 8? We expect changes of scatter in tensile test by the shape modification effect. Please indicate the scatter by adding error bars etc. in Fig. 8. Supposing the paper title, I'd like to request authors showing stress-strain curves of each alloys.
How much did casting defects contain? Results of tensile test were not dominated by the casting defects? Casting defects would be found in fracture surface of tensile specimen, if they exist. In my feeling, further elongation and ductility can be expected by phase ratio of aluminum matrix shown in Fig. 4.
There is possibility that not only Mg2Si but also Si particles etc. are damaged. The elastic modulus of Si is higher than that of Mg2Si. Therefore, interfacial peeling probably occurs easily due to mismatch of deformability.
At line 188, I cannot understand meaning of sentence that 'During tensile process, materials . . . . .'. Please state in detail.
With regard to conclusions, the first one (1) is not suitable for conclusion because authors had not mentioned anything about this. Authors should delete this. The third conclusion that Modified Mg2Si was origin of fracture is overstatement. There is no evidence in the manuscript.
Author Response
Dear reviewer
We have revised the manuscript taking all the comments and suggestions from review, which are very crucial to improve integrity of our article. We have also completed the change of plagiarism sentences as we advised.
Please address all correspondence concerning this manuscript to me at kbj@kitech.re.kr. I look forward to a critical and prompt review from your panels again.
Yours sincerely
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors,
Following are some remarks to the work:
1. Some values are written using ^ mark, e.g. 4500MNm^-2 please re-write with superscript.
2. In Experimental: please write the names of the supplier companies for all materials you have used in the work (Al, Cu, Zn, Mg, Si, master alloy).
3. In Experimental: what is the material of the mould, please specify.
4. I don’t understand what the values in Table 2 are? Did you get them by previous experiments? Did you get them from the literature (please add the source)? The same for Figure 2.
5. Your statement that of the modification of the Mg2Si phase as well as the reduction of the grain size in Figure 4, is not seen! I see the same morphological components as well as similar grain size of the modified alloy!
6. In Figure 5 you compare 2 alloys with different magnifications, that’s incorrect!
7. What is the reason of the line scan in Figure 6? It is usually used in coatings; you can make here a point scan.
8. Why tensile test results are not presented? Plot TS vs. elongation?
9. Please explain how the strength increases simultaneously with elongation? The basic tensile principals learn that when the strength increases, the elongation decreases and vice versa!
10. Authors contribution?
11. Conflicts of interests?
Author Response
Dear reviewer
We have revised the manuscript taking all the comments and suggestions from review, which are very crucial to improve integrity of our article. We have also completed the change of plagiarism sentences as we advised.
Please address all correspondence concerning this manuscript to me at kbj@kitech.re.kr. I look forward to a critical and prompt review from your panels again.
Yours sincerely
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Thank you for improving your manuscript.
I think that the revised manuscript is to understand easy for readers.
The manuscript is acceptable.
One comment;
format (font) of the added references (14, 15) probably should be revised because format is different to default format.
Author Response
Dear reviewer
We have revised the manuscript taking all the comments and suggestions from review, which are very crucial to improve integrity of our article.
Please address all correspondence concerning this manuscript to me at kbj@kitech.re.kr.
Yours sincerely
Author Response File: Author Response.pdf
Reviewer 2 Report
Dear Authors,
The work was significantly improved, but some remarks should be considered:
1. You have mentioned Thermo-Calc software calculations in Table 2, but you need to add basic principles of these calculations, otherwise it seems like you trust some computer calculations. Please add main principles and/or equations these calculations are based.
2. Figure 6b before and after revision is the same picture and has different scale bar. Are you sure you have revised?
3. After the addition of the strength vs. strain plots, that’s clearly seen that no change in yield strength has been achieved. Yield strength is the more valuable property in metal. How can you explain this?
Author Response
Dear reviewer
We have revised the manuscript taking all the comments and suggestions from review, which are very crucial to improve integrity of our article.
Please address all correspondence concerning this manuscript to me at kbj@kitech.re.kr.
Yours sincerely
Author Response File: Author Response.pdf
