Laser Powder Bed Fusion Processing of Low Cost CoCrFeNiMoxNby High Entropy Alloys with Promising High-Temperature Properties via In Situ Alloying Commercial Powders
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
In the paper under review " A blend of only commercial powders, including Ni625, CoCrF75, and 316L, were used as the raw material for fabricating non-equiatomic CoCrFeNiMoxNby high entropy alloys (HEAs) through laser powder bed fusion (PBF-LB/M) via in-situ alloying, instead of using pure elemental powders, thus reducing the raw materials cost", microstructure and mechanical properties have been also analized.
I find that the paper is interesting. At the same time the significance of the topic requires, at least in my opinion, a more depth explanation for justifing the results and giving more confidence to what the authors have found. So, I attach my advices in the following.
Comments for author File: 
Comments.pdf
Comments on the Quality of English Language
The English is good.
Author Response
Please find attached our responses.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
The manuscript is well written. However, in the part with phase formation it lacks additional analysis to prove the author's discussion. My questions and suggestions are:
1. It would be great to add powder size distribution after mixing
2. Fig.2. According to the figure and as there is no other explanation for the porosity calculation procedure, you have calculated porosity only once per sample. That’s insufficient. Please explain it or correct it. If there were more than one calculation, add statistical errors to the figure.
3. A good thing is maybe to use the Energy density parameter during the optimization process. Not only varied speed and laser power.
4. „The general trend observed was that the porosity amount increased with laser power at a given scanning speed due to over-melting, whereas too low a power of 100W also increased the porosity amount due to insufficient melting.”
This must be supported by microstructural analysis of defects and their morphology
5. The main drawback of the manuscript is in the „Fracture behavior part”. To prove the precipitation analysis and Laves phases occurrence EDS analysis is not enough. This part needs HRSEM or TEM analysis to prove the discussion and phase formation mechanism.
Author Response
Please find attached our responses.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
The topic of the article is relevant and interesting. The use of powdered materials can significantly expand the range of properties, and thus the application of products. Moreover, pre-alloying of powdered alloys allows for high homogeneity of structure and chemical composition, and thus performance properties.
However, for a better perception of the scientific results obtained, I propose to take into account the following comments.
1. It is worth paying attention to the title, since in this form it looks more like an abstract. For example: Laser powder bed fusion processing of low cost CoCrFeNiMoxNby high entropy alloys via in-situ alloying of commercial powders: Inconel, 3 CoCrF75, 316L, and INVAR.
2. The scientific novelty should be clearly stated. Show what problem the authors want to solve.
3. The parameters of high-temperature tensile strength measurement should be specified in more detail (medium, heating rate, exposure time, temperature).
4. The authors should perform a study of the microstructure in BSE mode because in this form Figure 1 is not very informative.
5. The method of porosity determination should be indicated. Moreover, it is necessary to indicate the measurement error by the optical method.
6. The text should contain a conclusion about the influence of the SLM process parameters on porosity. Since the figure shows a minimum in the dependence of porosity on scanning speed and laser power. How can this be explained? Moreover, it is worth combining graphs a and b in Figure 2 and adding the measurement error.
7. It is necessary to indicate how the relative density was measured. What theoretical density was measured relative to? Is it 100% minus porosity? In this case, this use of the term is incorrect. Moreover, the two decimal places (99.95...99.87) are strange.
8. In Figure 3, it is necessary to indicate which (SE or BSE) mode was used. In Figures a, b, c there are areas of black color (most of them in Figure 3c). Is this porosity?
9. Figure 4 b, c is of rather poor quality. Moreover, the mapping shows some heterogeneity in the distribution of chemical elements (nickel - Figure b, cobalt - Figure c). How can this be explained?
10. The authors should not compare the methods of obtaining and their impact on mechanical properties, but rather operate on such parameters as structure, chemical composition, phase composition, and stress. Moreover, the parameters of the mechanical properties measurement should be taken into account.
11. In Figure 9, porosity is clearly visible (black areas). If this is indeed porosity, it is much more than indicated in Table 4.
Author Response
Please find attached our responses.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
The paper has been improved.
