Effects of Annealing on the Microstructure and Wear Resistance of Laser Cladding CrFeMoNbTiW High-Entropy Alloy Coating
Round 1
Reviewer 1 Report
In this manuscript, the heat treatment influence on the structure and property profile of laser cladded FeMoCrTiWNb coatings is investigated. However, the investigated coating system deviates strongly from the intended equimolar composition. The fundamental question arises whether the presented data have representative validity. In this context, the manuscript title does not fit the investigated stratification system. In addition, numerous details are missing, which call into question the reproducibility of the results. In principle, the manuscript is thematically suitable for publication. However, a significant revision is necessary. Before publication, some aspects should be emphasized more clearly. In addition, the scope of validity must be restricted and a much stronger focus placed on the possibilities and limitations of the manufacturing technology. Without a clear revision, publication cannot be approved.
The abstract describes the desired equimolar coating composition. However, this is not present. Therefore, already in the abstract, the limited scope must be pointed out.
In the Introduction part, a justification for the material selection must be built in. It is not sufficient to point out that no heat treatment of laser clad coatings has been investigated for this particular alloy. What motivates the authors to investigate this alloy? What do you expect from heat treatment? What work is known on the alloy in bulk materials? What are the reasons for the selected heat treatment temperatures and times?
In the methodological part, it is necessary to specify which initial powder material was used? Which manufacturing method was chosen? What is specifically meant by "mortal machine". More detailed information on particle size distribution, morphology, etc. is completely missing. More detailed information is also missing on the laser cladding system used. Which working distance was used. How high was the focal point? Details of the laser are given, but the nozzle used is completely unclear. Which powder feeder and which feed rate was used? There is also a lot of information missing about the heat treatment. Which furnace was used? What atmosphere was used?
The results section should start with an analysis of the powder feedstock. How does the initial powder differ? What does the powder look like after mechanical alloying? Morphology and grain size distribution are the focus here. In addition, the chemical composition of the powder must also be investigated. Furthermore, a stronger focus should be given to the coating system. What has been achieved? Information on the general structure must be included. What is the character of the interface area to the substrate? How does it differ from the surface of the coating? Is there a chemical gradient? What is the degree of melting of the substrate material? This can be followed by the detailed study described.
A comparison of the formed structure with existing literature values (also in the field of bulk materials) is mandatory. Here, the real chemical composition should be taken as a basis. The results of the EDS measurement indicate that the intended chemical composition was not achieved. How to deal with this? Where does the carbon in the layer system come from? The gradient in the chemical composition should also be considered. Composition should also be recorded.
The conclusion is only a summary. Moreover, it does not reflect the results. With such a large change in chemical composition, it is not possible to refer to an equimolar system.
Line 36 Write percent sign without space next to number.
Line 44 "its initial stage" - needs more explanation. Numerous classical production methods have already proven to be suitable. What specifically is meant by this?
Line 62 Use a long hyphen when referring to the source and then insert a space before "It".
Line 108 Insert space 50 mm
Line 141 Rewrite "a loaded ode 200 gf".
Figure 1 - insert space before units
Figure 2 - "as cast" can be misunderstood and should be replaced by a designation that indicates the layer
Figure 4 - is a good place to include a cross-sectional view of the coating system.
Author Response
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Reviewer 2 Report
Major issue:
1. Roughness tests are suggested in replace of the adjectives used to describe wear phenomenon (line 287 to line 300). Also, the results should coincide with wear loss results.
2. Please show that the compositions listed in Table 2 are all match with the definition of HEA (mixing entropy value >1.6R)
3. Line 224 mentioned that the values in Table.2 are averaged numbers. Please provide more explanations on the variation range of each composition, to help understanding that the coating fabricated by laser cladding method may not be homogeneous.
Minor issues:
1. Naming of HEAs may follow the alphabet order, such as CrFeMoNbTiW. Arranging the elements by at% order is also acceptable.
2. The legend in Fig.4 should be corrected as "as-deposit".
Suggestions:
Maybe EBSD results could be a better way to illustrate the enhancement of hardness by different annealing conditions, for that the volume of hard phases would gradually increase as the annealing temperature raise.
Author Response
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Round 2
Reviewer 1 Report
Thank you for submitting the revised manuscript version. Unfortunately, marginal changes and additions were made. As previously mentioned, the validity range of the results is not sufficiently defined. Information on the feedstock material and coating system as well as their characterization are insufficient. The results have no added value for the scientific community as presented, since reproducibility is not possible on the basis of the existing data. The comments made in the first review still apply and must be considered. Due to the low revision progress, a rejection is recommended.
Author Response
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Reviewer 2 Report
- The legend (as-cast) in Fig.4 should be corrected as "as-deposit".
- Line 231 mentioned that the values in Table.2 are averaged numbers. Please provide more explanations on the variation range of each composition (e.g. averaged from how many measurement results, the standard error or standard deviation value, etc).
Author Response
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