High-Temperature Oxidation Behavior of Al_xCoCr_0.5NiPt_0.1 (x = 0.5, 1.0) Multi-Principal Element Alloys at 1100 °C

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper the authors studied the high temperature oxidation behavior of two high entropy alloys with different Al concentration. The results are interesting, however, they are not sufficiently discussed. The following comments should be considered:

1.The experiments were carried out in a muffle furnace by thermal cycling. The samples were periodically annealed, cooled down, removed from the furnace and weighted every 10 h. See lines 92-93. During thermal cycling, a part of the oxidation scale might have spalled down because of thermal coefficient mismatch between the scale and substrate. See, e.g., https://link.springer.com/article/10.1007/s11085-021-10048-5. It might have influenced the results. The total oxidation time was relatively short (100 h). Haven’t you considered carrying out a continuous annealing in a thermogravimetric chamber? The continuous annealing could shed more light on the oxidation behavior. By running a continuous TG experiment the influence of spallation might have been avoided.

2.The fitted curves in Fig. 3 clearly indicate that the oxidation kinetics is sub-parabolic. The coefficient is 0.14 and 0.18, i.e., it is well below the expected value of 0.5 (Eq 2). Parabolic behavior, i.e., diffusion-controlled reaction, is not followed. You should discuss and explain this behavior.

3.The rate constant given in Table 2 is not a parabolic rate constant since the parabolic rate law is not followed. See comment 2. You must properly define the dimension of the rate constant obtained.

4.The scale appears to be cracked in the case of the Al0.5 alloy (Fig. 6). It is likely that there has been a loss of the scale due to spallation which might have influenced the weight gain results. The rate constant might be underestimated. You have to properly discuss the oxidation kinetics behavior.

5.The authors also mention the depletion of Al in the near-surface region (line 190). However, the variation of Al concentration in the near-surface region cannot be seen from EDS maps alone (Fig. 6). You should include elemental line-scan in the manuscript to confirm the Al depletion.

6.On lines 243-244 the authors discuss the Al concentration necessary for the protective Al₂O₃ scale formation. It is concluded that 12 at. % Al is enough for the complete scale formation. This result has to be compared with previously studied high entropy alloys with comparable Al concentration.

7.You should provide a schematic of the corrosion mechanism in the manuscript.

Author Response

Dear Reviewer, first of all we would like to thank you for your constructive comments, which helped us to improve the manuscript and will be useful for our future work.

All corrections in the text of the manuscript are highlighted in yellow.

 

Reviewer 1

In this paper the authors studied the high temperature oxidation behavior of two high entropy alloys with different Al concentration. The results are interesting, however, they are not sufficiently discussed. The following comments should be considered:

1. The experiments were carried out in a muffle furnace by thermal cycling. The samples were periodically annealed, cooled down, removed from the furnace and weighted every 10 h. See lines 92-93. During thermal cycling, a part of the oxidation scale might have spalled down because of thermal coefficient mismatch between the scale and substrate. See, e.g., https://link.springer.com/article/10.1007/s11085-021-10048-5. It might have influenced the results. The total oxidation time was relatively short (100 h). Haven’t you considered carrying out a continuous annealing in a thermogravimetric chamber? The continuous annealing could shed more light on the oxidation behavior. By running a continuous TG experiment the influence of spallation might have been avoided.

Answer: We apologize for not describing the experimental procedure in sufficient detail. In reality, there was more than one sample in the furnace. The experimental procedures are described in detail in [18]. However, we have made a small insertion in the text in this manuscript to avoid misleading the reader.

"For each time interval, a separate sample was prepared from the ingot. Thus, ten samples were prepared for each composition, so that during the 100-h holding time, samples were removed one at a time every 10 h."

We also made revisions to the "Conclusion" section.

“The main directions for future work on these alloys as increasing the isothermal holding time to assess the stability of the oxide film formed on the surface and using continuous long-term thermogravimetric analysis to assess the convergence of results obtained using two different methods.”

2. The fitted curves in Fig. 3 clearly indicate that the oxidation kinetics is sub-parabolic. The coefficient is 0.14 and 0.18, i.e., it is well below the expected value of 0.5 (Eq 2). Parabolic behavior, i.e., diffusion-controlled reaction, is not followed. You should discuss and explain this behavior.

Answer: Yes, you're right. This needed to be discussed in more detail. The corresponding changes have been made to the manuscript.

“The general formula for oxidation kinetics can be represented as:

,                                                                                       (2)

where Δm is mass change (g), A is surface area (cm²), τ is the holding time (h), k and n are the simplified oxidation coefficient and dimensionless oxidation exponent, respectively. The n value can represent the different oxidation behaviors (n = 1, 0.5 and 1/3 correspond to the linear, parabolic, and cubic oxidation behaviors, respectively). The calculation results are presented in Figure 3. According to the obtained results, the values of n are quite low (0.144 and 0.183) and correspond more closely to sub-parabolic law (either cubic or logarithmic). The resulting films have a high degree of protection against further oxidation of the base metal. Thus, the diffusion of atoms and ions through the formed films and deep into the metal is hindered, which may be due to the effect of platinum on the high-temperature oxidation process. Platinum is known to block oxygen diffusion pathways [26].”

3. The rate constant given in Table 2 is not a parabolic rate constant since the parabolic rate law is not followed. See comment 2. You must properly define the dimension of the rate constant obtained.

Answer: Most of the data cited in the literature are calculated for a parabolic oxidation law. Therefore, to compare our data with those available in the literature, we calculated the oxidation rate parabolic constant. The corresponding explanations are included in the text of the manuscript.

“Although the oxidation process followed sub-parabolic law, we calculated the oxidation rate constant for a parabolic one to facilitate comparison of our data with literature data, as most calculations presented in the literature were performed for parabolic oxidation.”

4. The scale appears to be cracked in the case of the Al0.5 alloy (Fig. 6). It is likely that there has been a loss of the scale due to spallation which might have influenced the weight gain results. The rate constant might be underestimated. You have to properly discuss the oxidation kinetics behavior.

Answer: The corresponding changes have been made to the manuscript.

“It is noted that cracks were observed not only on the surface, but in the cross-section of the oxide film for the sample Al_0.5CoCr_0.5NiPt_0.1 MPEA (Figure 6a). However, we did not observe any film shedding throughout the high-temperature experiment. In the crucibles where the samples were located during the experiment, no particles or flakes were found that had fallen from the sample. It is possible that these defects arose as a result of cross-section sample preparation. Longer experiments are necessary to assess the stability of the formed film, which is a potential area for future research.”

5. The authors also mention the depletion of Al in the near-surface region (line 190). However, the variation of Al concentration in the near-surface region cannot be seen from EDS maps alone (Fig. 6). You should include elemental line-scan in the manuscript to confirm the Al depletion.

Answer: The corresponding changes have been made to the manuscript (see revised Figure 6).

6. On lines 243-244 the authors discuss the Al concentration necessary for the protective Al2O3 scale formation. It is concluded that 12 at. % Al is enough for the complete scale formation. This result has to be compared with previously studied high entropy alloys with comparable Al concentration.

Answer: The corresponding changes have been made to the manuscript.

“The calculating results that we obtained can also be compared with the data from Rong et al [46] for a number of Si-doped alloys. The value of 11.97 at. % for AlCoCr_0.5NiPt_0.1 MPEA is comparable with 10.7 at. % for (Co_32.4Cr₂₆Ni₃₃Al₈Y_0.6)₉₉Si₁ alloy [46] and superior to the value of 20.0 at. % for (Co_32.4Cr₂₆Ni₃₃Al₈Y_0.6)₉₈Si₂ composition [46].”

46. Rong, X.; Jiang, Q.; Li, X.; Qiu, Z.; Zhang, Z.; Yang, C. Role of silicon in promoting exclusive Al₂O₃ formation on (Co_32.4Cr₂₆Ni₃₃Al₈Y_0.6)_100-xSi_x medium-entropy alloys: Unraveling oxidation resistance mechanisms. J. Alloys Compd. 2026, 1056, 186653. Doi: 10.1016/j.jallcom.2026.186653.

 

7. You should provide a schematic of the corrosion mechanism in the manuscript.

Answer: The corresponding changes have been made to the manuscript (see new Figure 7).

“The diagrams of oxidation of the studied alloys are shown in Figure 7.

Figure 7. Schematic diagram of sample oxidation: (a) Al_0.5CoCr_0.5NiPt_0.1 and (b) AlCoCr_0.5NiPt_0.1.”

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors submitted a work, „ High-Temperature Oxidation Behavior of AlxCoCr0.5NiPt0.1 (x = 0.5, 1.0) multi-principal element alloys at 1100 °С” for consideration in Metals. The manuscript can be published after a major revision. My comments and suggestions are presented below:

Introduction

-Line 74-79. The last paragraph of the introduction should underline the novelty and aim of your work. Please focus more on the specific scientific gap your research addresses. What kind of scientific problem did you solve?   

Methodology

-Please clarify the size and mass of a single ingot.

-More details about metallography are needed. How did you prepare the samples for observation?

-„The chemical composition of the obtained ingots was controlled 86 using an OPTIMA 2100 DV inductively coupled plasma atomic emission spectrometer 87 (Perkin Elmer, Shelton, USA).” Where are the results of this analysis?

Results

- Table 1. How did you measure the chemical composition of dendrites and interdendritic spaces? EDX measurements lead to beam interaction with a large volume, potentially encompassing both regions. Is it an accurate measurement?

-Fig.2. Presentation of data below 40 ° does not make any sense.

- Fig.2. Position 63 deg in the (a) Al0.5CoCr0.5NiPt0.1. I do not see a peak from BCC. It is a flat curve.

-„The initial microstructure of as-cast samples and their phase composition, especially in terms of the distribution of aluminum between microstructural components, plays a significant role in the high-temperature oxidation resistance of alloys [33].”

Such sentences should be in the introduction or the conclusion, not here. I recommend removing this from here.

-What kind of device did you use for mass gain measurements?

- Fig.3. How many samples did you measure in the oxidation test? I do not see a standard deviation of mass gain points in both curves. What kind of function did you use for fitting?

-Fig.4 and 6. Please indicate the phases detected on the XRD spectrum in the SEM images.

- I recommend removing or better analyzing the part „Microstructure Stability of Alloys after Isothermal Holding at 1100 °”. Here is a very poor scientific discussion of the results. It is not an important part, given the title of the manuscript.

Conclusions

-„Platinum does not exist as a separate phase but rather is incorporated into solid solutions.” It is not surprising. What kind of phases did you expect, taking into account the very low Pt concentration?

- It is worth presenting some quantitative data in the conclusions.

Author Response

Dear Reviewer, first of all we would like to thank you for your constructive comments, which helped us to improve the manuscript and will be useful for our future work.

All corrections in the text of the manuscript are highlighted in green.

 

Reviewer 2

The authors submitted a work, „ High-Temperature Oxidation Behavior of AlxCoCr0.5NiPt0.1 (x = 0.5, 1.0) multi-principal element alloys at 1100 °С” for consideration in Metals. The manuscript can be published after a major revision. My comments and suggestions are presented below:

Introduction

-Line 74-79. The last paragraph of the introduction should underline the novelty and aim of your work. Please focus more on the specific scientific gap your research addresses. What kind of scientific problem did you solve?   

Answer: The corresponding changes have been made to the text of the manuscript.

“This study aims to fill a scientific gap in the production of multicomponent alloys doped with Pt with high resistance to high-temperature oxidation. The compositions proposed for this study were obtained for the first time and have not been previously investigated.”

 

Methodology

-Please clarify the size and mass of a single ingot.

Answer: The corresponding changes have been made to the text of the manuscript.

“100 gram conical ingots with a height of about 30 mm were obtained.”

-More details about metallography are needed. How did you prepare the samples for observation?

Answer: The corresponding changes have been made to the text of the manuscript.

“To determine the microstructure before and after high-temperature oxidation tests, thin sections were made. For this, a Delta AbrasiMet (Buehler, Leinfelden-Echterdingen, Germany) cutting machine, a SimpliMet 1000 (Buehler, Leinfelden-Echterdingen, Germany) pressing machine, and an EcoMet 250/AutoMet 250 (Buehler, Leinfelden-Echterdingen, Germany) grinder-polisher were used. Grinding (and subsequent polishing) was carried out sequentially on 250 μm, 75 μm, 25 μm, and 9 μm sandpaper, and a 3 μm diamond suspension was used for final polishing.”

-„The chemical composition of the obtained ingots was controlled 86 using an OPTIMA 2100 DV inductively coupled plasma atomic emission spectrometer 87 (Perkin Elmer, Shelton, USA).” Where are the results of this analysis?

Answer: The results agreed well with the EDS analysis (within 5% error). Therefore, to avoid cluttering the manuscript, we have added a footnote to Table 1. The changes made are as follows.

“** The EDS results for the average composition are consistent with the data of chemical analysis performed on OPTIMA 2100 DV inductively coupled plasma atomic emission spectrometer; the difference between the two determination methods does not exceed 5%.”

Results

- Table 1. How did you measure the chemical composition of dendrites and interdendritic spaces? EDX measurements lead to beam interaction with a large volume, potentially encompassing both regions. Is it an accurate measurement?

Answer: Dendrites are quite large, so EDS analysis of dendrites is error-free. Analysis of interdendritic phases is, of course, more complex, as analyzing small regions can introduce measurement error. However, as can be seen in Figure 1, not all regions of interdendritic layers are smaller than 5 µm; there are quite large regions measuring 10 µm. For our analysis of the interdendritic phase composition, we selected precisely these relatively large regions.

-Fig.2. Presentation of data below 40 ° does not make any sense.

Answer: We intentionally left these areas in the diffraction patterns to demonstrate that there are no additional peaks. Removing them might lead the reader to believe we were hiding something, which is not the case.

- Fig.2. Position 63 deg in the (a) Al0.5CoCr0.5NiPt0.1. I do not see a peak from BCC. It is a flat curve.

Answer: We have removed the mark at 63 degrees. The modified Figure 2 is included in the text of the manuscript.

-„The initial microstructure of as-cast samples and their phase composition, especially in terms of the distribution of aluminum between microstructural components, plays a significant role in the high-temperature oxidation resistance of alloys [33].”

Such sentences should be in the introduction or the conclusion, not here. I recommend removing this from here.

Answer: The corresponding changes have been made to the text of the manuscript. We have moved this sentence to the "Conclusion" section.

-What kind of device did you use for mass gain measurements?

Answer: Weighing was performed every 10 h on a Sartorius MSE225S-000-DU laboratory analytical balance (Sartorius Group, Göttingen, Germany) with an accuracy of 0.00001 g. For each time interval, a separate sample was prepared from the ingot. Thus, ten samples were prepared for each composition, so that during the 100-h holding time, samples were removed one at a time every 10 h.

- Fig.3. How many samples did you measure in the oxidation test? I do not see a standard deviation of mass gain points in both curves. What kind of function did you use for fitting?

Answer: We smelted three ingots for each composition and conducted three parallel high-temperature tests. The results were consistent, with no scatter. To obtain the approximation curve, we logarithmed the data (specific mass gain and holding time), processed the results in Excel (plotting a line), obtained the necessary coefficients, and then wrote a formula to plot the approximation curve. The corresponding changes have been made to the text of the manuscript.

“The results on the specific weight gain during a 100 h isothermal holding at 1100 °C are shown in Figure 3. Each point on the graphs represents the result of averaging three parallel experiments; the calculated errors did not exceed 5%.

The general formula for oxidation kinetics can be represented as:

,                                                                                       (2)

where Δm is mass change (g), A is surface area (cm²), τ is the holding time (h), k and n are the simplified oxidation coefficient and dimensionless oxidation exponent, respectively. The n value can represent the different oxidation behaviors (n = 1, 0.5 and 1/3 correspond to the linear, parabolic, and cubic oxidation behaviors, respectively). The calculation results are presented in Figure 3.”

-Fig.4 and 6. Please indicate the phases detected on the XRD spectrum in the SEM images.

Answer: Spinel formation was detected primarily on the film surface (Figure 5 and Table 3). It is virtually invisible in cross-section; the main phase for both samples is aluminum oxide. For the sample with a lower aluminum content, spinel formation is more obvious, while for the second sample, spinel inclusions are less common. We added line scanning (Figures 6c and 6d). Note that Figure 6c shows elevated oxygen, chromium, cobalt, and nickel contents on the surface, and the next layer in the film is aluminum oxide.

- I recommend removing or better analyzing the part „Microstructure Stability of Alloys after Isothermal Holding at 1100 °”. Here is a very poor scientific discussion of the results. It is not an important part, given the title of the manuscript.

Answer: You're right, this part isn't described in great detail, but we didn't want to remove it because readers might question our failure to address the microstructural changes. We did, however, study this issue.

We made revisions to the "Conclusion" section.

“Further studies should be also directed the change in mechanical characteristics and grain sizes after long-term high-temperature isothermal holding.”

 

Conclusions

-„Platinum does not exist as a separate phase but rather is incorporated into solid solutions.” It is not surprising. What kind of phases did you expect, taking into account the very low Pt concentration?

Answer: We decided to emphasize this point, as the formation of platinum aluminides is quite likely with increasing aluminum concentration. We prefer to keep this phrase, as it is correct and highlights the advantages of platinum compared to, for example, niobium or hafnium. Even small concentrations of niobium or hafnium can lead to the formation of intermetallic compounds. This is the main advantage of using platinum: it has high solubility in most metals. Furthermore (again, compared to niobium or hafnium additions), samples with platinum are smelted without problems and form dense, defect-free ingots.

- It is worth presenting some quantitative data in the conclusions.

Answer: The corresponding changes have been made to the text of the manuscript.

“In as-cast alloys, platinum exhibits high solubility in the BCC solid solution (about 6–7 at. %), but after prolonged high-temperature isothermal holding, the platinum concentration tends to equalize between the two solid solutions.”

“So, the maximum specific weight gain for the AlCoCr_0.5NiPt_0.1 composition was 0.675 mg/cm² against 0.965 mg/cm² for the Al_0.5CoCr_0.5NiPt_0.1 MPEA.”

“The calculated parabolic oxidation rate constant was k_p =45 × 10^–13 (g²/cm⁴s) and k_p = 20.2 × 10^–13 (g²/cm⁴s) for Al_0.5CoCr_0.5NiPt_0.1 and AlCoCr_0.5NiPt_0.1 MPEA accordingly.”

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The rationale for selecting the AlxCoCr₀.₅NiPt₀.₁ alloy system is not clearly stated. Please add one sentence in the abstract describing the research objective and why this specific composition is investigated.

Please include one sentence summarizing the key experimental findings in the abstract. This will help attract readers’ interest and enhance the overall impact and value of the manuscript.

 

In line 51, several references related to alloy systems are cited. Please provide a brief description (one sentence each) of these studies. This will help readers better understand the research background and the necessity of investigating the present alloy composition.

Figure 1 presents the microstructure of the alloys as a function of composition, and it appears to be observed at approximately 1000× magnification. However, this does not adequately represent the overall grain structure. Please include additional microstructural images at lower magnification (below 200×) in Figure 1 to provide a more comprehensive understanding of the microstructure.

The metallurgical analysis is well described overall. However, the discussion on fine grains is insufficient. To better characterize the grain structure, please include EBSD analysis results. This will help readers understand the heat-treated microstructure and phase evolution of the alloy.

Author Response

Dear Reviewer, first of all we would like to thank you for your constructive comments, which helped us to improve the manuscript and will be useful for our future work.

All corrections in the text of the manuscript are highlighted in red.

 

Reviewer 3

The rationale for selecting the AlxCoCr₀.₅NiPt₀.₁ alloy system is not clearly stated. Please add one sentence in the abstract describing the research objective and why this specific composition is investigated.

Answer: The corresponding changes have been made to the manuscript.

“This study aims to fill a scientific gap in the production of multicomponent alloys doped with Pt with high resistance to high-temperature oxidation. The compositions proposed for this study were obtained for the first time and have not been previously investigated.”

Please include one sentence summarizing the key experimental findings in the abstract. This will help attract readers’ interest and enhance the overall impact and value of the manuscript.

Answer: The corresponding changes have been made to the manuscript.

“The maximum specific weight gain for the Al_0.5CoCr_0.5NiPt_0.1 alloy was 0.965 mg/cm², and 0.675 mg/cm² for the AlCoCr_0.5NiPt_0.1 alloy. Based on the high-temperature oxidation experiment results, it was established that AlCoCr_0.5NiPt_0.1 MPEA exhibits greater resistance towards high-temperature dry air corrosion with the formation of exclusive Al₂O₃ scale on the surface with 3–5 μm thickness ; the parabolic oxidation rate constant for this alloy is k_p = 20.2 × 10^–13 (g²/cm⁴s). Introduction of platinum into the composition of the Fe-free AlCoCr_0.5Ni alloy reduces the value of the parabolic oxidation rate constant by half.”

In line 51, several references related to alloy systems are cited. Please provide a brief description (one sentence each) of these studies. This will help readers better understand the research background and the necessity of investigating the present alloy composition.

Answer: The corresponding changes have been made to the manuscript.

“The literature review also contains data on the positive effect on the heat resistance of Fe-free AlCoCrNi alloys when alloyed with Si [23], Ti [24], and Pt [25, 26]. Thus, Gawel et al in [23] showed that the introduction of silicon can promote Al₂O₃ scale formation; however, the main phase in the film remains Cr₂O₃. At the same time,Liang et al in [24] determined that the oxidation rate constant for the AlCoCrNiTi_0.1 alloy is three orders of magnitude lower than that of the AlCoCrNiTi alloy which may indicate that alloying with a small amount of an additionally introduced element is more promising and economically justified. Li et al. in [25] find out that the introduction of Pt ensures low oxide growth stress on the surface of NiCoCrAlPt high-entropy alloy. But, the introduction of a large amount of platinum is costly and causes the formation of intermetallic compounds, which affects the mechanical characteristics of the alloy. Previously, in [26], we found that the introduction of platinum not only promotes the formation of a dense protective layer of Al₂O₃ on the alloy surface but also increases the temperature of intensive scale formation to 1312 °C for AlCoCrNiPt_0.1 MPEA. At present, the optimal heat-resistant composition has not yet been determined; however, alloying with a small amount of platinum is a promising direction.”

 

Figure 1 presents the microstructure of the alloys as a function of composition, and it appears to be observed at approximately 1000× magnification. However, this does not adequately represent the overall grain structure. Please include additional microstructural images at lower magnification (below 200×) in Figure 1 to provide a more comprehensive understanding of the microstructure.

Answer: The corresponding changes have been made to the manuscript (see revised Figure 1).

The metallurgical analysis is well described overall. However, the discussion on fine grains is insufficient. To better characterize the grain structure, please include EBSD analysis results. This will help readers understand the heat-treated microstructure and phase evolution of the alloy.

Answer: This study is not a priority for this manuscript, but you are correct. In the future, we plan to pay closer attention to the mechanical properties of the alloys before and after high-temperature isothermal holding, as well as potential changes in grain size.

We made revisions to the "Conclusion" section.

“Further studies should be also directed the change in mechanical characteristics and grain sizes after long-term high-temperature isothermal holding.”

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for clarifying the procedure on how the kinetic experiments were carried out. It is acceptable that samples were removed one by one instead of thermal cycling, although continuous TG experiments would be more informative. The paper is acceptable for publication subject to minor revision:

The scale cracking (Fig. 6) could have also happened during cooling as it might be related to large differences in the thermal expansion coefficients of the substrate and oxide scale. See, e.g., https://doi.org/10.1016/j.intermet.2016.12.015, https://doi.org/10.1016/j.jmrt.2024.06.185, etc. It should be mentioned in the discussion.

Author Response

Reviewer 1

Thank you for clarifying the procedure on how the kinetic experiments were carried out. It is acceptable that samples were removed one by one instead of thermal cycling, although continuous TG experiments would be more informative. The paper is acceptable for publication subject to minor revision:

The scale cracking (Fig. 6) could have also happened during cooling as it might be related to large differences in the thermal expansion coefficients of the substrate and oxide scale. See, e.g., https://doi.org/10.1016/j.intermet.2016.12.015, https://doi.org/10.1016/j.jmrt.2024.06.185, etc. It should be mentioned in the discussion.

Answer: We express our gratitude to the reviewer for taking the time to review the manuscript and making a significant contribution to its improvement.

The corresponding changes have been made to the text of the manuscript. Changes are highlighted in dark yellow.

“Also to further assess the stability of the oxide film forming on the surface; it will be necessary to plan a series of continuous long-term thermogravimetric analyses with a planned heating/cooling time and a specific heating/cooling rate. Such experiments are necessary because cracks in the film can form during cooling of the samples upon removal from the furnace due to large differences in the thermal expansion coefficients of the substrate and oxide scale [39, 40]. On the other hand, both alloys under study were subjected to shock cooling, but cracks in the film formed in only one of them, providing further evidence of the heat resistance of the composition AlCoCr_0.5NiPt_0.1.”

39. Dąbrowa, J.; Cieślak, G.; Stygar, M.; Mroczka, K.; Berent, K.; Kulik, T.; Danielewski, M. Influence of Cu content on high temperature oxidation behavior of AlCoCrCu_xFeNi high entropy alloys (x = 0; 0.5; 1). Intermetallics 2017, 84, 52–61. Doi: 10.1016/j.intermet.2016.12.015.
40. Palcut, M.; Drienovský, M.; Priputen, P.; Šulhánek, P.; Stacho, P.; Gerhátová, Ž.; Gogola, P.; Krajčovič, J.; Bónová, L.; Kusý, M. Oxidation resistance of AlCoFeNiCu_x high entropy alloys. J. Mater. Res. Technol. 2024, 31, 1974–1990. Doi: 10.1016/j.jmrt.2024.06.185.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors submitted a revised work, „High-Temperature Oxidation Behavior of AlxCoCr0.5NiPt0.1 2 (x = 0.5, 1.0) multi-principal element alloys at 1100 °С” for consideration in Metals. The authors included all of my comments and suggestions in the revised manuscript. The manuscript can be published if other reviewers agree to it.

Author Response

Reviewer 2

 

The authors submitted a revised work, „High-Temperature Oxidation Behavior of AlxCoCr0.5NiPt0.1 2 (x = 0.5, 1.0) multi-principal element alloys at 1100 °С” for consideration in Metals. The authors included all of my comments and suggestions in the revised manuscript. The manuscript can be published if other reviewers agree to it.

Answer: We express our gratitude to the Reviewer for taking the time to review the manuscript and making a significant contribution to its improvement. Thank you for recommending the manuscript for publication.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Acceptable it.

Author Response

Reviewer 3

Acceptable it.

Answer: We express our gratitude to the reviewer for taking the time to review the manuscript and making a significant contribution to its improvement. Thank you for recommending the manuscript for publication.

Author Response File: Author Response.pdf