Masking Effect of LPSO Structure Phase on Wear Transition in Mg97Zn1Y2 Alloy
Round 1
Reviewer 1 Report
I think the research could be interesting, but paper presents serious flaws, and requires huge improvement. Recommendations are as follows.
- Casting process. Authors do not explain at all important aspects such as type of mould, amount of molten metal, or dimensions of casting. How is the homogeneity assured? I cannot believe a manual stirring of molten metal at 740 ºC, with just this description. Nothing about how heating is performed is given.
- How do authors avoid grain growth, typical of Mg alloys?
- Definition of wear tests is not adequate. I read several times but, for instance, manuscript indicates testing “until surface melting” (line 93) and a “sliding distance of 377 m” (line 99). Authors do not explain at all when they change the load (poor step definition). Looking at results, how intermediate points were measured? Do authors divide always by 377 m?
- How surface melting is detected? Do authors measure temperature during test?
- XRD patterns (JCPDS files) must be included, and planes cited. XRD has a rough limit of 5% detection, please include it in the discussion.
- When talking about phases, is alpha-Mg a pure phase or not? It should be described properly. Fig 2 suggests more phases, try to improve it. Is X phase continuous? Which is the amount of phases? More information is required.
- DSC description seems wrong. Authors talk about a eutectic, where is it? It is not found in the microstructure. The description of temperatures during heating and cooling is the same, clearly stating a bad interpretation of DSC. How are authors sure about melting of LPSO phase?
- Authors claim for 3 samples in each test, but no standard deviation is given in some tests. It is very difficult to believe the errors found in wear tests; in many cases, less than 1% error is obtained. My experience with wear indicates that this is strongly complicated, specially performing such a huge amount of tests.
- Explain a little bit more about LPSO in the introduction.
- What is DRX? And MML?
- Can authors show friction coefficients?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript is interesting and clear. I have found only two errors:
Line 326: it is 60N instead of 20N
Line 336: It is 200ºC instead of 100ºC
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript is devoted to the study of modern magnesium alloy, in particular, its wear resistance at elevated temperatures, which is a novelty in this field.
The cited references are relatively current (5 from 21 of them of the last 5 years). This ratio must be increasing. It is does not include self-citations.
I consider it possible to accept the work for publication after the following changes:
83 indicate the furnace used, the material and volume of the crucible, the method and tool of mixing
84 indicate the base of XRD used.
92 replace the absolute values of the load when determining the wear to the relative (N - MPa).
111 indicate that the microhardness was determined at the cross section.
120 indicate the numbers of the detected phases according to the used database.
121 replace XRD spectrum with the more common XRD pattern.
134 to clarify the mechanical properties - these are literary data (then the reference must be indicated) or measured by the authors (then the measurement error must be cited)
142 despite the authors' remark, it seems to me that it would be correct to bring wear at different temperatures on one graph, for greater clarity
152 it is necessary to explain the extreme decrease in wear with an increase in the load 130 - 140N, at a temperature of 150C.
303 correct the transfer of units of measurement to the next line.
307 indicate it is optical or electron microscopy, indicate that it is a cross cection.
310, 314, 318 about may be 200-210 or 200 mkm, but 281.5 mkm it's exactly. I think these exact values must be replaced with approximate ones.
349 it makes no sense to give two figures. It is necessary to bring all four graphs in the same coordinates, increase the drawing and change the range of the hardness axis from 0-130 to 70-130.
414 pay more attention to considering the data given in the table
416 Conclusions - expand the section
Author Response
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Round 2
Reviewer 1 Report
I appreciate the answers of the authors.
- Regarding previous question #2 (“How do authors avoid grain growth, typical of Mg alloys?”), please include your answer in the manuscript.
- Regarding previous question #3 (definition of wear test). I think it has been improved, but I still have two questions. The former, the length of each 20 N-step (I mean how long is each step in Figure 4). The latter, how were these steps measured? (I mean, did authors remove sample from wear equipment, measure and reinstall, or did they use different samples for each point).
- Regarding previous question #4 (“detection of surface melting”), please include your answer in the manuscript.
- DSC. I think I did not explain myself properly, please excuse me. I think phenomena are clear (melting of eutectic and so). But temperatures during heating or during cooling are not the same. When measuring in DSC, authors notice the starting of the melting of eutectic at 533.8 ºC. But during casting (lines 138-142) this temperature (or the other ones) are not the same. Temperatures measured when heating and cooling are not the same. This way, the description of lines 138-142 is not accurate. When casting, the eutectic will appear at another temperature (not exactly 533.8 as it is written). If authors have the DSC during cooling, they can include it and check it. If not, I mean just rewriting a little bit, as the eutectic “will solidify in a temperature close to that of 533.8 measured during heating”. The same with the other temperatures.
- Other things I found. Sorry I did not say them before. “Deformation” in Fig 5b is miswritten. Within the text, DRX is described in line 346 while it appears for first time in line 283.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
I agree with the corrections and comments of the authors to my previous comments, except for the remarks regarding the lines 142, 349. However, a very serious error was discovered in the work:
The first three figures are taken from an article published by the authors earlier (reference 10) and included in the results section. This is not allowed; the work cannot be published.
10. An, J.; Xuan, X.H.; Zhao, J.; Sun, W.; Liang, C. Dry sliding wear behavior and subsurface 473 microstructure evolution of Mg97Zn1Y2 alloy in a wide sliding speed range. J. Mater. Perform. 474 Eng. 2016, 25, 5363-5373.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
Thanks for the feedback
Reviewer 3 Report
I agree with the corrections and comments of the authors to my previous comment about the first three figures.
