Enhancing Strength and Toughness of Aluminum Laminated Composites through Hybrid Reinforcement Using Dispersion Engineering

Round 1

Reviewer 1 Report

In this article, the authors use hybrid reinforcing to produce aluminum matrix composite with a combination of in-situ and ex-situ reinforcement. While the results provided in this paper is of interest for the scientific community in this field, the paper needs major improvements and clarifications and cannot be published in the current form:

 

Abstract:

 

The authors claim in the abstract that they have used a novel approach to produce their composite while based on their literature review this approach is not novel and been used by others.

 

 

It is mentioned Al3BC particles were uniformly dispersed however you have not quantified this uniformity or there is no evidence in the paper showing such a uniform dispersion.

 

English and formatting improvement:

 

The manuscript needs improvement in both above aspects. For example:

There are extra spaces in line 3 of page 1 (introduction, in caption of Figure 3 after (Al), in line 4 of page 2 (before “due”) in page 5 middle of the page before “(Fig. 3 g)”. The sentence “While, the reinforcement settled in the Al grains interior increase dislocation blocking, and forest hardening. It is work,” in page 7 is incomplete.

The following sentence, “It is work …” does not make sense.

“Summarily” at the beginning of conclusion should be changed and the sentence better re-written.

 

Discussions:

 

Can you explain how your “an easy and innovative route” differs  from the way other researchers have done the same?

 

The meaning of semi-coherent bonding is not clear.

 

The discussion and use of hardening terms such as Orowan and forest hardening in the text is not critical; they are used without proper definition, explanation and referencing. There are other terms such as misorientation angle in Figure 3 which is not explained in the text. You need to make sure whatever you use are referred to in the main text.

 

The references in the caption of figure 5 must be also used in front of legends.

Why Reference [10] does not have any point in Figure 5?

Have you used all the available research data points from literature in Figure 5?

 

There is no implication of future for the application of this research neither in abstract not in conclusion.

So what next after you have done this research? Where can be applied? What are the next steps? If you have improved something what are the implications?

see the comments

Author Response

1. The authors claim in the abstract that they have used a novel approach to produce their composite while based on their literature review this approach is not novel and been used by others.

• We thank the referees for their valuable comments and suggestions. We acknowledge the concerns raised by the novelty of our method described in the summary. After re-evaluating our work and considering the reviewers' comments, we acknowledge that the word 'novel' may not be appropriate to describe our approach, and we apologize for the confusion that has arisen. While it is true that some of our methods, such as in situ synthesis and in situ reinforcement, have been used before in the literature, our work New - Create a hybrid aluminum matrix composite with higher strength. and ductility. In our study, we synthesized in situ nanoscale Al3BC particles in ultrafine grain aluminum by incorporating carbon nanotubes (CNTs) into elemental powder mixtures, followed by mechanical activation and subsequent annealing.The resulting in situ nanoscale Al3BC particles are uniformly dispersed within the elongated UFG Al particles, resulting in improved strength and strain hardening.The innovation of our method lies in the combination of in situ synthesis of nanoscale Al3BC particles in UFG aluminum; this will help improve the uniform distribution of the product and create a strong interface with the matrix. This combination allows us to strike a balance between strength and ductility, which is a major challenge in composites.To address reviewers' concerns, we've updated the Summary to better reflect the latest advances in our research on combining in-situ and in-situ reinforcement to achieve desired properties in the composite. We hope this revision will reflect participation and progress in our research.

Abstract: In this work, we propose a hybrid approach to solve the challenge of balancing strength and ductility in aluminum matrix composites. While some elements of our approach have been used before, such as in situ synthesis and ex situ augmentation, our work innovates by combining these techniques with specialized equipment to achieve success. We synthesized nanoscale Al₃BC particles in situ in ultrafine particles by incorporating carbon nanotubes (CNTs) into elemental powder mixtures, followed by mechanical activation and annealing, to obtain granular (UFG) aluminum. The resulting in situ nanoscale Al3BC particles are uniformly dispersed within the UFG Al particles, resulting in improved strength and strain hardening. The innovation in the unique combination of nanoscale Al₃BC particles synthesized in situ in UFG aluminum provides better integration with the matrix and a strong interface. This combination provides a balance of strength and flexibility, which is a major breakthrough in composites. (Al₃BC, CNT)/UFG Al composites exhibit a simultaneous increase in strength (394 MPa) and total elongation (19.7%), indicating increased strength.

 

2. It is mentioned Al3BC particles were uniformly dispersed however you have not quantified this uniformity or there is no evidence in the paper showing such a uniform dispersion.

• Thank you for your valuable feedback. We apologize for any confusion this may have caused and appreciate the opportunity to address this concern.To rectify this, we will include additional characterization data namely a TEM image in Figure 2(f), in the revised paper to demonstrate the uniformity of the Al3BC particle dispersion within the ultrafine-grained (UFG) aluminum matrix.

 

 

3. The manuscript needs improvement in both above aspects. For example:

There are extra spaces in line 3 of page 1 (introduction, in caption of Figure 3 after (Al), in line 4 of page 2 (before “due”) in page 5 middle of the page before “(Fig. 3 g)”. The sentence “While, the reinforcement settled in the Al grains interior increase dislocation blocking, and forest hardening. It is work,” in page 7 is incomplete.

The following sentence, “It is work …” does not make sense.

“Summarily” at the beginning of conclusion should be changed and the sentence better re-written.

• We appreciate your valuable feedback. All these issues was solved.

4. Can you explain how your “an easy and innovative route” differs from the way other researchers have done the same?

• We thank the referee for asking questions about the "simple and innovative method" mentioned in the summary. We apologize for any confusion caused by the lack of specific details about how our approach differs from other researchers. We appreciate the opportunity to explain many aspects of our manufacturing process and provide more information.

According to the experimental section, a "simple and novel method" for the production of (Al3BC, CNT)/Al composites appears to have high-speed shear, uniform CNT layer on the surface of the Al sheet, and growth of sheets achieved using a micro. -rolling (MMR) process Composite materials. The below text was added to the manuscript to avoid any confusion.

 

“This method differs from those used by other researchers in several ways:

 

High speed cutting and coating: high speed cutting is used to break the CNT group and B as a new step in manufacturing.

This step allows carbon nanotubes to be dispersed on the aluminum matrix, which can improve the mechanical properties.

Micro-Micro Rolling (MMR) Process: The MMR process involves micro-scale rolling of composite materials and appears to be a unique and innovative process for the production of laminated composites. This process will introduce microstructures and textures that can help improve the properties of (Al3BC, CNT)/Al composites.

In-Site Formation of Al3BC: The in situ formation of Al3BC particles in composites by the reaction of Al particles with B and carbon elements and subsequent annealing distinguishes this method from another method based on the addition of preformed particles. This in situ synthesis provides better control of the size, distribution and coupling between the material and the matrix.

Low growth of Al3BC: This method relies on solid state reaction to produce low growth resulting Al3BC particles, resulting in nanoscale Al3BC particles with unique properties. The presence of Al3C4 can also assist in forming submicron-sized heterogeneous core layers such as Al3BC particles.

Minimal damage to CNTs: Experiments show that CNTs suffer little or no major damage during predispersion, extrusion and MMR; which suggests a careful and well-optimized approach to preserve the integrity of CNTs in composites. In summary, the "simple and new method" (Al3BC, CNT) / from other research methods to produce Al composites, high-speed cutting, joining the uniform CNT layer of Al sheets and using the MMR process and the formation of Al3BC particles. This particular step results in a unique microstructure and properties that distinguish the composite from other aluminum matrix composites in the literature.“

 

5. The meaning of semi-coherent bonding is not clear.

• Thank you for your insightful comment. The below explanation was added to the manuscript.

“In the (Al₃BC, CNT)/Al composite, the Al₃BC particles are in-situ synthesized and embedded within the Al matrix. The orientation relationship between the Al₃BC particles and the Al matrix is represented by (0111) Al₃BC // (111) Al, which means that the crystallographic planes of Al₃BC align with those of the Al matrix. This alignment allows for a better fit between the two materials, resulting in fewer mismatch dislocations at the interface. Thus, the in-situ-Al₃BC/Al interface demonstrates a strong bonding, which effectively minimizes the presence of mismatch dislocations at the interface (Fig. 3h), corroborating the findings reported in previous studies [1,2]”

6. The discussion and use of hardening terms such as Orowan and forest hardening in the text is not critical; they are used without proper definition, explanation and referencing. There are other terms such as misorientation angle in Figure 3 which is not explained in the text. You need to make sure whatever you use are referred to in the main text.

• We appreciate your valuable feedback. We tried to edit and add the below sentense in the manuscript.

Enhanced strength in composites can be achieved through promoted movable dislocation-reinforcement interactions, leading to improved performance following the Orowan strengthening phenomenon [3]. The Orowan strengthening is a result of the force exerted on a dislocation to bypass particles within the matrix [4]. In this context, Al₃BC nanoparticles are uniformly dispersed throughout the laminated UFG Al grain, with the interparticle spacing estimated to be approximately 170-190 nm, close to the particle diameter of about 190 nm. The intragranular Al₃BC nanoparticles and Al₃C₄ in nanorod form could store mobile dislocations in the form of Orowan loops in internal region of Al grains during straining, more effectively providing HDI stress hardening and forest dislocation hardening. This result is consistent with the results reported by Liu et al. [4]. This can reduce the ratio of Orowan strengthening to total strengthening. Considering the overall ultimate tensile strength, other strengthening mechanisms come into play. These mechanisms include forest hardening, which arises from dislocation–dislocation interactions due to a relatively higher dislocation density, and GB strengthening, resulting from the presence of UFG Al grains. Both of these factors significantly contribute to the overall enhancement of the strength of material. The presence of nanoparticles (Al₃BC, Al₂O₃) or even Al₃C₄ nanorods causes mechanical incompatibility and promotes dislocation formation, (mostly misorientation less than 3 is taken into account as dislocations [5,6]), resulting in stronger dislocation-dislocation interactions and forest dislocation strengthening. Also, during deformation, GBs prevent dislocation movement due to the misorientation of adjacent grains. Higher misorientation causes resistance to movement [7,8]. In addition, UFG Al has a large GB compared to grain size, resulting in greater resistance to movement and higher stress. Dislocations from LAGBs (approximately 28%) result in a combination of easy sliding and depositing in the Al lamella, resulting in a combination of high elongation while maintaining high tensile strength. This finding is consistent with the literature mentioned above.

7. The references in the caption of figure 5 must be also used in front of legends.

• The figure edited and the appropriate citation were included in front of the legends.

8. Why Reference [10] does not have any point in Figure 5?

• Thank you very much for the comment. We added Ref. [10] and also some other works in the Figure 5c. Furthermore, while there are numerous pieces of literature that could be potentially included in Figure 5, we have deliberately selected only those studies with matrices that are most relevant to ours. This focused approach ensures a more meaningful comparison within the figure, allowing us to highlight the performance of our composite relative to similar materials. Moreover, if you think we should include a specific paper, please tell us to include its results as well.

 

9. Have you used all the available research data points from literature in Figure 5?

• No, we have not used all the available research data points from literature in Figure 5. Instead, we have selectively chosen data points from either studies that use matrices similar to ours or the ones that have similar philosophies to ensure a relevant and meaningful comparison. This approach allows us to highlight the performance of our composite in comparison to other materials that are more directly comparable in terms of composition and processing. By focusing on the most relevant data points, we aim to present a clear and concise representation of our composite's mechanical properties and its position relative to other similar materials in the literature. 

10. There is no implication of future for the application of this research neither in abstract not in conclusion.

• We appreciate the reviewer's feedback regarding the lack of implications for future applications in both the abstract and conclusion of our research paper. We apologize for the oversight and will address this concern in the revised version of our manuscript. In the abstract, we will include a brief statement about the potential future applications of our novel (Al3BC, CNT)/Al composite. We will highlight how the unique combination of in-situ Al3BC nanoparticles, CNTs, and the laminated structure can lead to improved mechanical properties, and we will briefly mention possible engineering applications that could benefit from such enhanced materials. Likewise, in the conclusion, we will explicitly discuss the implications of our findings for practical applications. We will emphasize the importance of the developed composite's exceptional strength and ductility and how these properties can make it a promising candidate for various engineering applications that demand both high strength and toughness. By addressing this aspect in both the abstract and conclusion, we aim to provide a clearer understanding of the practical significance and potential future uses of our research. We thank the reviewer for pointing out this important aspect, and we will ensure to incorporate it into the revised manuscript.

If the reviewer has any further suggestions or specific areas they would like us to focus on, please feel free to share them with us. We are committed to ensuring the relevance and practicality of our research.

11. So what next after you have done this research? Where can be applied? What are the next steps? If you have improved something what are the implications?

• We appreciate your valuable feedback. After conducting this research on the novel (Al3BC, CNT)/Al composite, several future directions and potential applications can be explored:

This paragraph was added to the manuscript.

 

Several future directions and potential applications can be explored. Composite materials have a good combination of high strength and ductility and find applications in many industries. It is used in lightweight, aerospace, and automotive performance improves fuel efficiency, and reduces emissions. In addition, the mechanical properties of composite materials in the medical field facilitate the production of implants and medical devices. To further advance the practical applications of the (Al₃BC, CNT)/Al composite, more research can focus on improving the manufacturing process to achieve products using better technology. Exploring the differences and combinations between Al₃BC and CNTs can provide composite materials with unique properties for different applications. Additionally, studying the behavior of composites in different environments such as high temperatures or corrosive environments will provide insight into specific applications.

 

More explanation was provided for the respected reviwer in the fllowing:

 

• Implications of Improvement: The successful synthesis and incorporation of in-situ Al3BC nanoparticles and CNTs in the aluminum matrix represent a significant improvement over traditional aluminum composites. The enhanced mechanical properties, including increased strength, ductility, and strain-hardening capacity, offer promising implications for materials engineering and design. The potential to develop lightweight and high-strength components with improved performance and reliability can lead to advancements in various sectors and contribute to sustainable engineering practices. Technology Transfer: The findings of this research could be transferred to industries involved in the production of advanced composite materials. Collaborating with manufacturing companies could facilitate the scaling-up of the fabrication process for commercial production. Furthermore, collaboration with academic institutions and research centers can encourage knowledge sharing and pave the way for further innovations in the field. Multi-Material Composites: Building upon the success of the (Al3BC, CNT)/Al composite, future research could explore the incorporation of additional reinforcement materials or multi-material composites. Combining different nanoscale reinforcements with specific functionalities can lead to synergistic effects, resulting in even more tailored and high-performance materials. Overall, the implications of this research are not only limited to enhancing the properties of (Al3BC, CNT)/Al composites but also extend to the broader scope of materials science and engineering, offering potential advancements in various industries and contributing to the development of innovative and sustainable technologies.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Question 1: The authors are requested to indicate the specific substance represented by the antipolar chart icon in Figure 3(a).

Question 2: Could the authors provide a detailed explanation of the intended message conveyed by region c in Figure 3(c)?

Question 3: The identification of the gray spherical substance as Al3BC in Figure 3(d) is not explicitly stated. It is suggested that the authors consider including an energy spectrogram or Fourier transform to support this identification.

Question 4: Is there a possibility that the black area depicted in Figure 3(f) corresponds to a different substance? The authors are advised to include an additional electron diffraction map as a supplementary analysis.

Question 5: Based on the data provided in Figure 3(h) and the mismatch formula, it is clear that the interface is not a semicommon-lattice interface, and the authors are advised to reconfirm the interface type.

Question 6: The authors are requested to state whether the Al3C4 generated in the composites will have any effect on the composite strength and toughness, and if so, to specify the effect.

Question 7: Figure 4(a) in the paper shows TEM images of (Al3BC, CNT/Al) and CNT/Al laminate composites, however, Figure 4(a) is only a TEM image of one type of composite, please ask the authors to modify this image and provide multiple TEM images with different multiplicities and regions.

Question 8: At the end of the 23rd line on page 5 of the text, it is mentioned that "the red arrow in Figure 3f", but there is no red arrow in Figure 3f in the actual text, and there may be similar expressions in the text, so the authors are requested to search for and revise the whole text by themselves.

Question 9: the full text of the picture size needs to be re-labeled by the author, pay attention to the size and location of the labeling, to be uniform and beautiful.

Question 10: The conclusion part of this paper is too weak, and it is suggested that the authors combine the strengthening mechanism to provide a strong summary of the results of the research on strengthening the toughness of composite materials.

It is ok. Thanks.

Author Response

Reviewer#2:

Question 1: The authors are requested to indicate the specific substance represented by the antipolar chart icon in Figure 3(a).

• Thank you for your valuable comment. In response to the query regarding the specific substance represented by the antipolar chart icon in Figure 3(a), we acknowledge your observation. The antipolar chart icon in Figure 3(a) corresponds to the EBSD data analysis, which provides insights into the microstructural characteristics of the composite material. This chart signifies the distribution of crystallographic orientations within the material and aids in understanding the grain structure and texture. Legend: We increased the size of the legend in the right bottom size in the figure 3(a), and graphical abstract.

Question 2: Could the authors provide a detailed explanation of the intended message conveyed by region c in Figure 3(c)?

• In Figure 3(c), region c highlights a specific area of interest within the microstructure of the composite material. This region represents a critical aspect of our study, showcasing the interactions and distribution of various nanoparticles and constituents within the material. In summary, Figure 3(c) is strategically included to elucidate the specific interactions and distribution of nanoparticles within the material, shedding light on their role in enhancing the mechanical properties and overall performance of the composite. Here is the added explanation in the manuscript.

"Figure 3c shows the presence of nanoparticles, including Al₃BC and possibly Al₂O₃, as well as Al₃C₄ nanorods, within the laminated Al grains in the microstructure. These nanoparticles contribute to the improvement of mechanical properties by inhibiting dislocation motion, strengthening GBs, and providing additional mechanical incompatibility to promote the generation of dislocations. The specific arrangement and distribution of these nanoparticles play a significant role in reinforcing the material, enhancing its strength, and potentially improving its ductility. Furthermore, the inclusion of Figure 3(c) is consistent with our emphasis on understanding the synergistic effects of various components on the behavior of composites. These areas provide visual evidence of how these nanoparticles are dispersed in the microstructure, supporting their importance on the overall mechanical behavior of the composite."

Question 3: The identification of the gray spherical substance as Al3BC in Figure 3(d) is not explicitly stated. It is suggested that the authors consider including an energy spectrogram or Fourier transform to support this identification.

• Thank you for your valuable feedback. We appreciate your suggestion to enhance the identification of the gray spherical substance in Figure 3(d) as Al3BC. We agree that providing additional supporting information is important for clarity and scientific rigor.

In response to your suggestion, we will consider including a Fourier transform (Figure 3j) in our analysis to further confirm the identification of the gray spherical substance as Al₃BC. By employing these techniques, we aim to provide a more comprehensive and reliable characterization of the material's composition and microstructure.

Thank you for your guidance in enhancing the quality of our research.

Question 4: Is there a possibility that the black area depicted in Figure 3(f) corresponds to a different substance? The authors are advised to include an additional electron diffraction map as a supplementary analysis.

• Thank you for your valuable feedback. I provided an additional electron diffraction map of Al4C3 (Insert in Figure 3 (f)) as a supplementary analysis.

Question 5: Based on the data provided in Figure 3(h) and the mismatch formula, it is clear that the interface is not a semicommon-lattice interface, and the authors are advised to reconfirm the interface type.

• We appreciate your keen observation and guidance regarding the characterization of the interface type in our research. We acknowledge the importance of accurately identifying and describing the nature of the interface within the composite material. Based on your comments, we re-examined the data shown in Figure 3(h) with the correlation formula to assess the link quality. In figure 3(h), we just tried to specify the interface without mentioning any kind of interface. Also in the manuscript, we changed the corresponding discussion.

 

Question 6: The authors are requested to state whether the Al3C4 generated in the composites will have any effect on the composite strength and toughness, and if so, to specify the effect.

• Thank you for your inquiry regarding the potential impact of the Al3C4 phase generated within the composites on their strength and toughness. We appreciate your attention to this aspect of our research. The below paragraph was added to the manuscript.

“The presence of Al₃C₄ in the composite has an effect on the strength and ductility of the product. Al₃C₄ is a special phase with its own mechanical properties that contributes to all composite materials. The presence of Al₃C₄ nanorods can act as additional reinforcement in the composite. These nanorods may impede dislocation motion and contribute to forest hardening, thus enhancing the strength of the composite. In addition, strong interfacial bonding can be achieved by forming an appropriate amount of Al₄C₃, which can promote load transfer and enhance the fracture elongation of CNT/Al composite. The size of Al₄C₃ is the most important factor affecting the mechanical properties of the composite. In this study, the interfacial bond was improved, while the mean diameter of the short Al₄C₃ rods in composite was as small as ~30-35 nm, thus, therefore, obtains more outstanding elongation (19.7%). Because it is a strong combination, it is not easy for microcracks to form and propagate at the interface during plastic deformation. The effect of Al₃C₄ on curing is more complex and needs further analysis and research. However, since Al₄C₃ is a brittle phase, excess Al₄C₃ negatively affects the mechanical properties of the composite.“

Question 7: Figure 4(a) in the paper shows TEM images of (Al3BC, CNT/Al) and CNT/Al laminate composites, however, Figure 4(a) is only a TEM image of one type of composite, please ask the authors to modify this image and provide multiple TEM images with different multiplicities and regions.

• Thank you for your careful observation and feedback regarding Figure 4(a) in our paper. We appreciate your suggestion to enhance the representation of the composite materials in the TEM images. In response to your comment, we modified Figure 4 to include multiple TEM images that showcase various multiplicities and regions within both types of composites. This will ensure a more complete depiction of the microstructure and enable readers to better understand the differences and characteristics of the two composite materials.

Question 8: At the end of the 23rd line on page 5 of the text, it is mentioned that "the red arrow in Figure 3f", but there is no red arrow in Figure 3f in the actual text, and there may be similar expressions in the text, so the authors are requested to search for and revise the whole text by themselves.

• Thank you for pointing out the inconsistency in our text and referring to an element in Figure 3f that does not actually exist. We appreciate your meticulous review and are committed to rectifying this discrepancy. Upon your comment, we have thoroughly reviewed the entire manuscript to identify and correct any similar expressions or references that may be misleading or inaccurate. We understand the importance of maintaining precision in our descriptions and references to the figures.

 

Question 9: the full text of the picture size needs to be re-labeled by the author, pay attention to the size and location of the labeling, to be uniform and beautiful.

• Thank you for your comment. We changed some labels, to be uniform and more beautiful in the text.

Question 10: The conclusion part of this paper is too weak, and it is suggested that the authors combine the strengthening mechanism to provide a strong summary of the results of the research on strengthening the toughness of composite materials.

• Thank you for your comment. We completely re-write the conclusion, and try to include the reviewer comment.

 

Author Response File: Author Response.docx

Reviewer 3 Report

In the present study, a Al3BC-CNT/Al composite was prepared. Its microstructure and phase composition was characterized. The composite exhibited enhanced mechanical properties. This work provides interesting results and can be accepted for publication after some revisions.

1) According to the processing and the microstructure of the Al3BC-CNT/Al composite, the "laminated" is not suitable to describe the material.

2) The final main composite contained 1 wt.% Al3BC, ~ 0. 45 wt.% CNTs, ...,How to determine their contents.

3) Is there a reaction between Al3C4 and B to form Al3BC?Al3C4 was detected in the composite, see Fig. 3f.

4) The contributions of Al3BC and CNT to the improvement of strength and ductility should be discussed. In addition, there is about 2.6 wt.% Al2O3, large than 1 wt.% for Al3BC. Therefore, the role of Al2O3 in the improvement of properties is not ignored.

Minor editing of English language required

Author Response

In the present study, a Al3BC-CNT/Al composite was prepared. Its microstructure and phase composition was characterized. The composite exhibited enhanced mechanical properties. This work provides interesting results and can be accepted for publication after some revisions.

• According to the processing and the microstructure of the Al3BC-CNT/Al composite, the "laminated" is not suitable to describe the material.

 

• We appreciate the reviewer's attention to detail and their comments on the use of the term "laminated" to describe the microstructure of the Al3BC-CNT/Al composite. While we value the reviewer's perspective, we respectfully disagree with the suggestion to avoid using "laminated" in our description. The justification for our use of the term "laminated" is based on the evidence provided in Figure 3 (a) through the EBSD image, which clearly shows a microstructure characterized by thin, flat layers or plate-like structures. This observation is consistent with our other publications [9-11] and confirms that the MMR process indeed imparts a laminated microstructure to the composite. We believe that the term "laminated" accurately describes the microstructural arrangement observed in the material and helps convey the essential feature of the MMR process in our research. By using this term, we aim to provide a clear and concise representation of the microstructural characteristics, which aligns with the primary focus of our study on the novel approach and mechanical properties of the Al3BC-CNT/Al composite. In light of the evidence provided by the EBSD image and our other publications, we maintain that the term "laminated" is suitable and appropriate for accurately describing the microstructure of our composite material. We believe its use contributes to a comprehensive understanding of the material's features and aids in effectively communicating our research findings to the readers. We sincerely thank the reviewer for their valuable input, and we respectfully stand by our choice of terminology based on the evidence presented.

 

• The final main composite contained 1 wt.% Al3BC, ~ 0. 45 wt.% CNTs, ...,How to determine their contents.
• Thank you for your valuble comment. Regarding Al3BC content, the peak intensities of the Al3BC phase in the XRD pattern was used to estimate its weight percentage in the composite.
• Regarding CNT content: The CNT content in the composite was assessed through Raman spectroscopy. CNTs and Al₄C₃ has characteristic Raman peaks that can be used to identify their presence and estimate their concentration. By comparing the Raman signal from the composite to known standards, we can estimate the CNT content.

In the supplementary materials, the edited sentence as given in the following was added.

“The final main composite contained 2.8 wt.% Al₃BC,  0. 45 wt.% CNTs, and  2 wt.%. Al₂O₃. The CNT content in the composite was assessed through Raman spectroscopy. For comparison, the 1.5 wt.% CNT/Al without B addition was also fabricated with the same procedure.”

• Is there a reaction between Al3C4 and B to form Al3BC?Al3C4 was detected in the composite, see Fig. 3f.
• Thank your for the valuabe comment. We appreciate the reviewer's attention to this aspect of our work and the opportunity to further elucidate the complex interplay of phases and reactions within the composite. The formation of Al3BC within the composite is primarily attributed to a reaction involving Al particles, the B element, and carbon generated during the decomposition of stearic acid during the fabrication process, followed by subsequent annealing. While the presence of Al3C4 has been detected in the composite, it is important to note that the formation mechanisms of Al3BC and Al3C4 are distinct. The detected presence of Al3C4 could indeed play a role in influencing the formation of Al3BC. It is hypothesized that Al3C4 may act as a nucleation site for the platelet Al3BC particles, contributing to their heterogenous nucleation and submicron-sized structure. This interaction between Al3C4 and B may be responsible for the observed microstructural features. While the primary formation route of Al3BC is through the reaction between Al particles, B, and carbon from stearic acid, the presence of Al3C4 and its potential role in influencing Al3BC formation is an interesting aspect that warrants further investigation and discussion in future research. This would provide a more comprehensive understanding of the interactions and mechanisms at play during the composite fabrication process. Indeed, the formation of Al₄C₃ can result from CNTs that have undergone partial damage and even atomic carbon originating from stearic acid when subjected to elevated sintering temperatures.
• In the manuscript, this aspect of nucleation and limited growth of Al3BC was mentioned as given in below.

The formation of Al₃BC is mostly caused by the reaction Al particles with the B element and the carbon formed due to the decomposition of stearic acid during fabrication process, and subsequent annealing [12]. Indeed, due to the appearance of some area where boron and carbon atoms are supersaturated, Al₃BC particles are in-situ nucleated as homogeneously in solid state with a limited growth rate. In fact, due to very low solubility of boron and carbon atoms in Al especially at solid state reactions [13,14], the growth process of Al₃BC particles is soon compromised by the deficiency of carbon and boron atoms, consequently nanoscale Al₃BC particle are formed. However, the presence of Al₃C₄ effectively contribute to heterogeneously nucleate platelet Al₃BC particles with submicron size [15,16]

• The contributions of Al3BC and CNT to the improvement of strength and ductility should be discussed. In addition, there is about 2.6 wt.% Al2O3, large than 1 wt.% for Al3BC. Therefore, the role of Al2O3 in the improvement of properties is not ignored.
• We appreciate the reviewer's feedback. We added the below discussion about the point requested by the reviewer.

“Incorporating both Al₃BC and Al₂O₃ improves the mechanical properties of the composite material. This improvement is mostly achieved through Zener drag, which occurs when dispersed particles are randomly distributed within the material matrix. The effectiveness of Zener drag depends on various factors such as the nature, geometry, size, spacing, and volume fraction of the particles [17]. In our composite, the presence of these nanoparticles effectively prevents the migration of both HAGBs and LAGBs. As a result, dynamic and static recrystallization is hindered, and grain growth is restrained. This characteristic allows the composite to retain its mechanical properties in advanced aluminum-based MMCs. The introduction of CNT and some γ-Al₂O₃ on GBs significantly reduces their dis-location annihilation efficiency, thereby contributing to the occurrence of back stress hardening. On the other hand, reinforcements embedded within the grain interior of Al enhance dislocation blocking and forest hardening, leading to an advanced ap-proach to achieving ultra-high strengthening and toughening efficiency through in-tragranular/intergranular dispersion engineering.

Additionally, the integration of CNTs within the GBs significantly hinders the movement of dislocations across the interface between aluminum and CNTs [18]. This obstruction of GB motion is more effective with CNTs due to their elongated nanofiber-shaped structure compared to nearly spherical nanoparticles [19]. The unique morphology of CNTs provides a strong impediment to dislocation movement within the composite. By reinforcing the material, CNTs synergistically enhance its strength through mechanisms such as load distribution and dislocation inhibition while preserving the inherent ductility of the aluminum matrix.

Therefore, the combined effects of Al3BC, Al2O3, and CNTs contribute significantly to the overall improvement of strength and ductility in the composite. These materials work together through various mechanisms, including Zener drag, dislocation inhibition, and load distribution, to enhance the mechanical properties of the composite while maintaining the malleability of the Al matrix. This multifaceted enhancement strategy opens up possibilities for advanced materials with superior mechanical performance suitable for a wide range of applications. This advancement represents a progression beyond the work of Jiang et al. [20]. The presence of a well "Arranged array of in-situ formed hybrid nanoparticle-rich zones, surrounded by CNT-decorated GBs, synergistically enhances both strength and ductility in the composite material.”

• Minor editing of English language required.
•  

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Most of concerns are addressed. but the issue with uniformity remains.

How do you define uniformity based on which arrows in figure 2(f) shows that? I do not see uniformity in figure 2(f). Is the form and position of particles in this figure repeats in all samples and is similar throughout each sample? 

This should be resolved.

Author Response

In our study, the term "uniformity" refers to the even distribution and consistent presence of Al3BC particles throughout the UFG Al matrix. We apologize if the visual representation in Figure 2(f) did not effectively convey this concept. To address your concern, we would like to clarify that the arrows in Figure 2(f) were intended to highlight the presence of Al3BC particles in the UFG Al matrix. However, we understand that a more detailed description of uniformity and its depiction in the figure could enhance clarity. Regarding the form and position of particles, we acknowledge that the figure might not provide a comprehensive view of the entire sample set. The form and position of particles in Figure 2(f) might vary due to the inherent microstructural variations within the composite material. While we aimed to capture representative areas, we recognize that a single image might not fully capture the overall consistency.

In addition, we can confidently state that the form and positions of the particles depicted in Figure 2(f) are consistent and replicated in the majority of the other images, encompassing over 90% of the additional samples studied. This uniformity in the appearance and arrangement of particles across multiple samples underscores the reliability and reproducibility of our findings.

The below explanation was added to the manuscript to solve this issue, hopefully, fall into accepted by the respected reviewer.

“The criteria that were used to evaluate uniformity encompass the absence of localized clustering or agglomeration of Al3BC particles, ensuring that their distribution is not sporadic but homogeneously spread across the UFG Al. Uniformity is assessed through various characterization techniques, including the TEM image in Fig. 2(f), which, despite its limitations in representing the entire sample, provides a visual indication of the general distribution trend. Furthermore, the uniform distribution of Al3BC particles contributes to consistent mechanical reinforcement across the composite material. This is because the interactions between dislocations and Al3BC particles are optimized when particles are evenly distributed, leading to enhanced strengthening effects.“

Author Response File: Author Response.docx

Reviewer 2 Report

The author has been all addressed my comments, hence I recommend to accept.

Author Response

n/a

Reviewer 3 Report

All questions have been answered. It can be accepted for publication.

Minor editing of English language required

Author Response

n/a

Round 3

Reviewer 1 Report

Can be accepted.