Effect of Heat Treatment on Microstructure and Aqueous Corrosion Properties of AlCoCrNiFe High Entropy Alloy
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article is devoted to the study of High Entropy alloys (HEAs). The AlCoCrNiFe alloy was annealed at different temperatures.
I have several questions and comments to the authors.
1. There are no explanatory captions in Figure 1. Specify which chemical element is shown in each photo. It is not clear now which element is where.
2. The authors state in their conclusions that the effect of heat treatment on microhardness is insignificant, but the graph shows differences of more than 200 units, i.e. 660 and 440 HV. Explain this conclusion.
3. The authors state in their conclusions that the effect of heat treatment on the microstructure is insignificant. Section 3.1. Microstructure Investigation provides only SEM-EDS mappings of the as-received AlCoCrNiFe HEA. The effect of heat treatment on the microstructure is not described in sufficient detail, but a conclusion is made on this parameter. It is necessary to supplement the description of microstructural changes during heat treatment.
4. The results of corrosion studies require explanation. How from Figure 6, the results given in Table 2 were obtained?
5. The design of the manuscript requires improvement. Many shortcomings and errors.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe author's team studied the effect of heat treatment on the microstructure and corrosion properties of AlCoCrNiFe alloy systems. The motivation and presentation of the work are clear. However, several major issues need to be clarified/addressed.
1. I strongly suggest the author team clarify more by changing the terminology of 'corrosion' to 'aqueous corrosion' since high-temperature corrosion behaves very differently and might show opposite trends compared to the study shown in this paper. This needs to be done throughout the whole paper and also reflected in the title.
2. It would be helpful to provide a summary table or figure showing phase fractions of each phase for samples annealed at different temperatures, comparing data from XRD/SEM measurements and CALPHAD predictions. Similarly, provide those for phase compositions.
3. Please clarify if the length scale of hardness measurements are much larger than the microstructural features. If not, please provide statistics of micro-hardness measurements, e.g. an SEM figure showing the dents of measurements and microstructures (such as GB and precipitations).
4. Please show the microstructure/corrosion section of each sample after the corrosion test.
Please also check the reference of the paper since there are several 'Error! Reference source not found' in the draft.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have reported the effects of heat treatment equiatomic AlCoCrNiFe high-entropy alloys (HEAs) within a solution treatment temperature range of 800-1100 °C. The phase, microstructure, mechanical properties, and corrosion characteristics of the as-deposited alloy were studied and compared with heat-treated samples. Please incorporate following suggestions:
1. Please provide the make and model details for SEM and EDS.
2. Please provide the make and model details for XRD.
3. Please label figure 1 for each element as it is not celar to identify which image is for which element.
4. Please mention how many measurements were taken for EDS spectrum.
5. What ‘Error! Reference source not found’ mean in line 128?
6. Please provide JCPDS reference number for the XRD images in figure 4.
7. What ‘Error! Reference source not found’ mean in line 167?
8. Please correct ‘Table 2’ mentioned in line 184 as it is Table 1.
9. The ‘Table 1’ needs to be formatted as the caption is overlapping on the table and is not clear.
10. Please provide JCPDS reference number specifically for the oxides formed for the XRD images in figure 7.
11. Please reformat reference numbers as they are numbered twice.
12. In the ‘Results and Discussions’ section only once references from 14-17 are cited in line 234. This section looks a report of the experimental observations and calculation results. Please strengthen this section by providing in-depth scientific explanation and relevant references specifically for the XRD and corrosion results from the other research works reported on AlCoCrNiFe HEA alloys.
Comments on the Quality of English LanguageModerate editing of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have substantially revised the manuscript. They have responded to my comments. I recommend this article for publication in this version.
Author Response
Thanks for your help reviewing our work!
Reviewer 2 Report
Comments and Suggestions for AuthorsThe author's team made good efforts to improve the manuscript. For the micrograph (after corrosion tests) added, can the author also add the cross-section of the sample so the (potential) layered structure of oxide/metal can be better revealed?
Author Response
Comment: The author's team made good efforts to improve the manuscript. For the micrograph (after corrosion tests) added, can the author also add the cross-section of the sample so the (potential) layered structure of oxide/metal can be better revealed?
Response: We appreciate the reviewer’s suggestion to include cross-sectional imaging to better reveal the potential layered structure of the oxide/metal interface. However, we believe that the SEM is unlikely to reveal meaningful details of the oxide layer due to the extremely thin nature of the oxide layer, which will make it very difficult to distinguish it from the HEA substrate (which will have a similar contrast). Also, the preparation for the cross-section samples in such cases is very challenging and will mostly be unsuccessful. Since the primary aim of this study is to investigate the corrosion resistance and surface morphology after corrosion rather than to characterize the internal structure of the oxide layer, we believe that additional cross-sectional imaging would not substantially enhance the understanding of our results.
Thanks again for your help in improving the quality of our work.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript quality is improved after addressing the comments by the reviewer's and can be accepted in the present form.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Thanks for your help in improving the quality of our work, the English of the paper was reviewed and a few edits were made to improve it.
