Microstructure and Oxidation Behavior of Nb-Si-Based Alloys for Ultrahigh Temperature Applications: A Comprehensive Review
, Laihao Yu 1, Tao Fu 1, Jie Wang 1, Hong Wang 1,2 and Kunkun Cui 1Round 1
Reviewer 1 Report
In this work, the authors systematically reviewed the microstructural and oxidation behavior of Nb-Si-based alloys for ultrahigh temperature applications. Then it highlights the most fruitful modifying elements to promote oxidation resistance in detail. I think the author has conducted a thorough investigation and a detailed summary of his predecessors and their work and recommend an acceptance of coatings after some minor revisions
- In the Conclusion and prospect section, authors should extend their discussion on some aspects in this field that are worth studying in the future. Currently, it is limited.
- In figure 1a, the temperature should be 800°C in the top right corner.
- In figure 12b, authors should use a different identifier for images; current identifiers (a,a1, b, b1, etc.) are the same as the identifiers of the subfigures.
- Is there a potential of inviting adverse effect of adding modifying elements such as Hf, Cr, Zr, B, and V to Nb-Si base alloy? For example, what happens to corrosion resistance or surface mechanical strength? Some discussion or future prospects will be helpful for the audience.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work reported that Nb-Si based superalloys have high-temperature structural materials. Therefore, they have poor oxidation resistance which is a major obstacle for these application. However, there are serval issues in this paper which should resolved before acceptance.
1. Novelty should be clearer in the introduction.
2. More references related to effect of metal oxide should be added such as doi.org/10.1039/C6CP07135J, doi.org/10.1016/j.msea.2020.140663 doi.org/10.1016/j.compscitech.2020.108383, doi.org/10.1016/j.matchar.2019.110051 and doi.org/10.1016/j.pmatsci.2020.100663, and doi.org/10.1016/j.ceramint.2021.08.041
3. I think the author should add some analyses such as TEM and SEM after modification of alloy in section 3.1 if possible.
4. Figure 4, cross-section is not clear, especially d and e.
5. in Figure 5, is there relation between the crystallinity and morphology.
6. Regarding Figure 7, why authors did not study the weight gain with temperature?
7. Conclusions, could you add what is the future applications?
8. If the authors can add comparison between different alloys in advantages and disadvantages, this will make their review stronger.
9. The review will be suitable for pushing after addressing for issues above
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Authors addressed all comments and the present form is suitable to publish.
