The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Plasma-Cladded CoCrFeNiMn Coatings on Compacted Graphite Iron

Round 1

Reviewer 1 Report

The work analyses the effect of heat treatment on the microstructure and mechanical properties of the CoCrFeNiMn. The authors have done good work and reported a number of experiments to support the conclusion. However, the quality of English can be improved to improve the impact of the paper. The following edits are suggested to improve the paper:

1. Repeated use of the word "glorious". Kindly use another adjective in place of glorious. 

2. Line 43 "Well progress". Please rephrase it.

3. Line 49: High entropy alloy. Please use abbreviations after it has been introduced.

4. Line 52- Give references.

5 Line 63- 66: 

During the preparation of the coating by plasma transfer arc cladding, the quick heating and cooling characteristics of the alloy "create the elements solidify" before they can diffuse, leading to a lot of segregation and internal stress concentration that affects the coating’s properties

Do you mean: Due to fast cooling in plasma transfer arc cladding, the elements solidify before they can diffuse, leading to segregation and creation of stress concentration in the region?

6. Line 72: Improvement compared to what?

7. Line 76: What is HVOF? The abbreviation has not been defined before.

8. Highlight the importance and significance of the research in the introduction. How can the results presented in the paper be beneficial?

9. At the end of introduction add a paragraph describing different sections in the paper.

10. Line 123 (and in many other places) chemical compositions of the powders were (are) summarized in Table 1.

11. Figures in the paper have been referred to as "figure" and "Fig," through out the paper. Please be consistent and use either Figure or Fig. to refer the images. 

12. Section 3.1- provide reference to the previous work where similar grain sizes and solidification have been observed. The explanation for the solidification thermodynamics is not clear.

13. Figure 7. Specify different sections.

14. In section 3 overall good job has been done describing the results observed from the experiments. However, the discussion on why the results were observed needs to be strengthened. If proper explanation is not available please specify that this can be area for future exploration.

15. There is no section 4. 

The quality of English can be improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors, the topic of HEA is very urgent for today to expand their applications. I read Your manuscript, and here below are my comments and recommendations, on how to improve it:

Line 20-21: "To strengthen and improve wear resistance (performance) of the surface" INSTEAD OF "the surface and improve... achieve the purpose of surface modification and strengthening".

Line 43. Event? Please, check the word. The meaning is not clear. In other places, the unclear words or expressions will be highlighted in red. It means, that generally the meaning may be caught, but usually different wards are used in these cases. So, it would be good to change the "red words" to more appropriate ones.

Line 70: lower wear weight loss... wear track width

Line 102-107. In the cited references above there were works focused on the effect of post-heat treatment. I think it is better to rephrase as "but minor attention was paid to the effect of heat treatment..."

Lines 112-114: combine these 2 sentences into one.

Line 120. Alloy powder

Line 134. 10 mm/min: please, check this value. It seems to be a very slow speed. 10r/min? Please, correct

Figure 1B is useless. Make it at a bigger magnification (say 1-3K) or remove it. And yes, it is a cross-section, but no microstructure is visible. So, it is not a "cross-sectional microstructure"

Table 3. Do we need it? It may be easily replaced with 1 simple sentence. By the way, why did You select 30, 60, and 90 min. time intervals for heat treatment? Please, refer to the literature and prove, that these time intervals are good enough for HT

170: not 3 columns: the microhardness test was repeated 3 times for each sample to increase the accuracy

Line 176, 181. Use the correct sign for the diameter

Line 181. What is N80? Please, describe this material and its condition (hardness)

Please, describe the wear test more correctly. Was it a pin drilling over the plate (the pin rotates around its axis), or it was a rotation with a very small radius? If 2nd, then replace frequency by rpm, and specify the radius of rotation and sliding speed. Did You use lubrication?

Fig. 7: it would be very informative to see the microstructure of the transition zone between the GCI and the coating. Do we have the carbides there? Which type of carbides were formed?

Why You did not show how the microstructure after 30 and 60 minutes was changed? You may place them in 3 columns, on one page. It would be very informative.

Figure 8 should at least the image and EDS mapping for as-cladded sample, according to the data in Tab. 4.

Table 4. What was the mode of heat treatment for the sample mentioned in it? Please, add the data of all the tested samples, or at least - all the samples heat treated during 90 minutes

Line 203-206. From this it is unclear, which HT temperature is better. Please, describe and analyze all microstructures, and prove Your choice of 780C during 90 minutes (because in most following figures You study this particular sample). Why 90 minutes are better then 30 and 60?

Line 235-237. This sentence is unclear. Please, rephrase it

Figure 10c. Please, put the degrees over each peak: it will be very beneficiary 

Line 274-275. Please, point these peaks by the arrow. I can hardly understand what are You speaking about.

Did You measure the lattice parameter using TEM data? It is a good chance to cross-check the results from Fig. 10C. It will greatly add to the manuscript. Put the lattice parameter values into the graph

You did not do EDS using TEM? It would show the elements partitioning even better than during SEM studies

Line 304. Did You do any heat treatments at 25C?

Line 338-340. No, they could have never caused so huge fluctuations, especially for 1000C coating. The reasons - are the processes on the friction surface. Please, make a correct explanation

Figure 13. Why do we need the right picture? (13b ?)

Please add one picture of the sample after the friction test with entire the friction surface captured. This time, it is not clear what did You measure (the width of the wear track)

Line 366-368. The microhardness of the solid solution and other alloy parts was not studied in this research, or these results were not included. As well as the partitioning of Fe-Cr solid solution. We can not see it no the Please, 

It is very hard to find adhesion in Fig. 14. It is a combination of abrasive and delamination wear. To find out, do higher magnifications of the discussed "adhesion" areas.

Line 390. You did not do any tests to prove the existence of oxidation-type friction-induced structures. Please, prove their existence, and then - use them to explain the friction mechanism. Also, the cross-sections of the samples are needed: the delamination may be caused by fatigue, or by surface plastic deformation.

Line 336. What is slotted wear?

When the friction surface is described correctly, You may start to re-assess the wear mechanism.

Line 415. Where the undercutting was detected?

Comments for author File: Comments.pdf

Many words are used incorrectly

Author Response

Please see the attachment.

Author Response File: Author Response.pdf