Effects of Ce-Rich Misch Metal on the Microstructures and Tensile Properties of as-Cast Mg-7Al-3Sn-1Zn Alloys

Round 1

Reviewer 1 Report

Notes on the article of Guo-Jun Liu, Yan-Hua Sun, Nan Xia and Xiao-Fang Guan “Effects of Ce-rich misch-metal on the microstructures and ten-sile properties of as-cast Mg-7Al-3Sn-1Zn alloys”

The paper reports results of studying the structure and mechanical properties of the as-cast Mg-7Al-3Sn-1Zn wt.% alloy with different content of rich misch-metal (Mm). The alloying with Mm promotes the formation Al₄Mm phase and confines the formation of Mg₁₇Al₁₂ phase. The authors also studied the effect of different microstructural states on the mechanical characteristics of the alloy at room and elevated temperatures. The authors have done good research and analyzed the results carefully. But, in my opinion, the level of academic English should be improved. This is an interesting report, which should be published after revisions that are listed below:

• Table 1. The decoding of the * symbol is not given (for example, La*, Nd*).
• The details of the DSC analysis should be described in more detail (which crucibles were used, the atmosphere, the mass of the test sample, whether a standard was used).
• Table 3. Typically, data are presented as M ± m (where M is the mean, m is the standard deviation). If the authors give a different type of experimental error, then they should write in detail in the "Materials and Methods" section how the calculation was carried out.
• It should be written {0001}<110> and {102}<101> instead of {0001}<11-20> and {10-12}<10-11>.
• Authors claim «Since the increasing deformation temperature of 175°C promoted the basal slip and activated the non-basal slip of Mg alloys, however, the ductility of ATZE7312 was slightly weak compared to ATZ731 possibly related to the non-uniform deformation caused by the progressive ac-cumulation of Al₄Mm phases during tensile tests». Authors should provide the results of the texture analysis that support their statement or provide references to relevant literature.
• No decoding of the abbreviation EL_f.
• The authors talk about the influence of structural parameters on the mechanical properties of the alloy. However, not a word has been said about the texture factor. Meanwhile, texture is known to have a strong effect on the mechanical characteristics of magnesium alloys..
• Conclusions section, # 3. Instead of "... ~ 239MPa, ~ 108 MPa and ~ 19.6% at RT and ~ 148MPa ..." you should write "... ~ 239 MPa, ~ 108 MPa and ~ 19.6% at RT and ~ 148 MPa ...".

Author Response

Dear Editor/Reviewers,

  The authors would like to thank you and the reviewer for constructive comments and suggestions. We have revised our manuscript in view of your comments and suggestions. The comments are very valuable, and certainly helpful for revising and improving the quality of our manuscript. The authors sincerely hope that you would find the revised version of our manuscript suitable for publication in Metals. The revised portions are marked by blue font in the revised manuscript. Our detailed response on the reviewers’ comments is provided below.

Author Response File: Author Response.pdf

Reviewer 2 Report

Following flaws should be solved before potential publishing in the Metals.

1. Revision of texting, e.g.:

p.1. “biomedical due”

p.1.”  To modify these coarse micro-structures, Mg-Al-Sn-Zn alloys were designed by Zn addition and developed making them the good choice compared to AT alloys [18-20].

p.2.” the addition of Sn had better be in-creased a little, while the Al moderately decreases.”

p.2. “it is a pos-sible method by reducing the volume fraction of Mg17Al12”

p.3.” The Al4Mm phase formed can be explained”

p.3 “and the experiments prepared by gravity casting”

p.7 “In word, …..of Mn” – entire paragraph is very confusing.

etc...

2. Indicate error for average grain size.
3. Discussion of mechanical properties should be revised. Despite a significant drop in elongation for the alloy with 2%, the authors indicate this effect as a minor effect, while, a similar increase in elongation for the alloy with adding 0.5 or 1% Mm is taken as a remarkable improvement. This is not correct. The change in mechanical properties for alloy with 2% of Mm should be explained based on the obtained results. Probably proper analysis of the amount of the second phase could help. So far, all explanations (based on fracture analysis) are speculative. In addition changes in strength for investigated alloys are comparable if measurement error is taken into account. Therefore, there is no significant effect of Mm addition on TYS.

4. If authors take into account twinning activity during tensile tests, they should provide a confirmation for it, as from deformation curves it is unlikely that twinning is activated.

Author Response

Dear Editor/Reviewers,

  The authors would like to thank you and the reviewer for constructive comments and suggestions. We have revised our manuscript in view of your comments and suggestions. The comments are very valuable, and certainly helpful for revising and improving the quality of our manuscript. The authors sincerely hope that you would find the revised version of our manuscript suitable for publication in Metals. The revised portions are marked by blue font in the revised manuscript. Our detailed response on the reviewers’ comments is provided in the attached "Response to reviewer for Metals-1407269".

Sincerely,

Guojun Liu

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors carefully revised the article and answered all questions. I recommend to accept the revised version of the article in the present form. 

Author Response

Dear editor/Reviewers:

The reviewer’s positive feedback and detailed suggestions have helped us to improve the quality of manuscript. We appreciate gratefully to the positive comments and suggestions from the reviewers.

Thank you very much for your consideration to our paper for publishing in Metals.

Sincerely,

Guo–Jun Liu

Author Response File: Author Response.pdf

Reviewer 2 Report

I appreciate your careful revising of the paper.

However, there are few issues requiring minor revision.

1. Authors use an unusual way to present errors for tensile properties. Authors are recommended to use a standard way for specifying the error. For example in the case of 150(+1)(-2), it should be 150+/-2. Text should be modified accordingly (that explanation for positive and negative errors should be deleted, it is the wrong approach).
2. It is necessary to introduce error values for the volume fraction of the second phase and grain sizes.
3. The same style for indexing the crystallographic planes (3 or 4 indexing, see p9) should be used.
4. p.10, grain boundary slipping --> grain boundary glide
5. p.11 "the slightly decreased YS of 91 MPa in constrast with ATZ731 of 95 MPa " - there are same if we are taking into account the error bar. It is advised not to highlight things that are not strong enough.
6. it is highly recommended to skip the last two sentences in Results and Discussion, which are related to twinning activity as there is no twinning activity.
7. There are still some grammar mistakes and unfortunate formulations. Please revise your paper carefully.

Author Response

Dear editor/Reviewers:

We are pleased to submit the attached manuscript, entitled “Effects of Ce-rich misch-metal on the microstructures and tensile properties of as-cast Mg-7Al-3Sn-1Zn alloys” (Metals-1407169), to this journal.

The reviewer’s positive feedback and detailed suggestions have helped us to improve the quality of manuscript. We appreciate gratefully to the positive comments and suggestions from the reviewers. According to the reviewer's valuable suggestions, we have carefully made changes including "Errors, English language " to improve the quality in revised manuscript according to reviewer’s suggestion. Please consider its suitability for publishing in Metals.

Thank you very much for your consideration to our paper.

Sincerely,

Guo–Jun Liu

Author Response File: Author Response.pdf