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In-situ fabrication of graphene-nickel matrix composites
Accepted Manuscript In-situ fabrication of graphene-nickel matrix composites Jinlong Jiang, Xingxing He, Jinfang Du, Xianjuan Pang, Hua Yang, Zhiqiang Wei PII: DOI: Reference:
S0167-577X(18)30395-1 https://doi.org/10.1016/j.matlet.2018.03.039 MLBLUE 24000
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
17 December 2017 23 February 2018 4 March 2018
Please cite this article as: J. Jiang, X. He, J. Du, X. Pang, H. Yang, Z. Wei, In-situ fabrication of graphene-nickel matrix composites, Materials Letters (2018), doi: https://doi.org/10.1016/j.matlet.2018.03.039
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
In-situ fabrication of graphene-nickel matrix composites Jinlong Jiang a,b,c , Xingxing Heb, Jinfang Dub, Xianjuan Pangc, Hua Yangb, Zhiqiang Weib a. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu, China b. Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, Gansu, China c. National United Engineering Laboratory for Advanced Bearing Tribology, Henan University of Science and Technology, Luoyang 471023, Henan, China Abstract: Graphene-nickel (G-Ni) matrix composites were fabricated through in-situ growing graphene in bulk nickel matrix using a powder metallurgy method. Sucrose as precursor of graphene was dispersed into nickel powders to grow graphene, avoiding a traditional dispersion process of graphene in metal matrix. Multi-layer graphene was synthesized in-situ in nickel matrix, meanwhile nickel matrix was densified at high temperature. The nickel matrix acts as support and catalyst of graphene, and graphene grow in-situ in nickel matrix serving as reinforcement. This in-situ growth method offers a homogeneous dispersion of graphene and well-contacted interfaces between graphene and nickel matrix, which provides a guarantee for high load transfer from nickel matrix to graphene. Keywords: graphene; metallic composites; in-situ fabrication; microstructure; mechanical properties
Corresponding author. Tel./fax: +86 931 2976040. E-mail address: [email protected]. 1
1. Introduction Graphene is an ideal nanostructured reinforcement for metal matrix composites because of its unique two dimensional structure and outstanding physical and mechanical properties [1, 2]. The great challenge for developing high performance graphene-metal composites is to disperse graphene into metal matrix uniformly. Many methods [3-7] have been developed to solve the aggregation problem of graphene caused by the strong van der Waals interactions and incompatibility between graphene and metal matrix. The ball-milling is an effective and practical technique to disperse graphene into the metal. However, it would inevitably introduce lots of structural defects in graphene as a result of severe deformation [6]. The melting and stirring method is not applicable to graphene-metal composites because the large density difference between graphene and metal causes graphene to easily float on the top of metal [7]. Also high melting temperature of metals easily triggers a serious interface reaction between graphene and metal matrix [8]. Although the liquid dispersion methods are flexible to solve the agglomeration problem of graphene, the residual groups from organic solvents could be introduced into the composites. In this paper, enlightened by the fact that the growth temperature and atmosphere conditions of graphene on nickel substrate are similar to those of a powder metallurgy sintering process of nickel matrix composite, we propose an in-situ fabrication of G-Ni composites by growing graphene in bulk nickel matrix using a facile powder metallurgy method. 2. Experimental 2
Nickel powders (10 g, 300 meshes) and sucrose (80, 160, 240, 320 mg) were mixed in 150 mL of deionized water. This powder mixture was stirred mechanically at 120 °C until water was entirely evaporated. Subsequently, the powder mixture was cold-compacted for 10 min in a metal mold at a pressure of 380 MPa. Finally, the green compact was sintered at 1100 °C for 40 min in a quartz tube furnace. The sintered process was conducted at a heating rate of 10 °C min-1, under a mixed H2/Ar atmosphere (H2 200 sccm, Ar 500 sccm) with a chamber pressure of 900 Pa. After sintering, the samples were cooled to room temperature at a rate of 10 °C min-1. 3．Results and discussion 3.1 Structure characterization
Fig. 1. A schematic diagram of the in-situ fabrication process of G-Ni composite. Fig.1 shows a schematic diagram of the in-situ fabrication process of the G-Ni composites. Different from the conventional powder metallurgy process, sucrose as precursor of graphene instead of graphene was dispersed into nickel powders. The graphene directly grew from a pressed green compact of nickel powders covered with sucrose at a high-temperature sintering process. The nickel matrix acts as support and catalyst of growth of graphene, and the in-situ grown graphene serve as the reinforcement of nickel matrix. It is seen from Fig. 2 that carbon signals from 3
graphene are very uniform, which proves that graphene distributes uniformly in nickel matrix. A dissolution-precipitation growth mechanism can explain the graphene growth on nickel [9].
Fig. 2. (a) SEM and optical (inset) images of the G-Ni composite and corresponding EDS mapping for (b) carbon and (c) nickel elements. Fig. 3a shows the XRD patterns of pure nickel and the G-Ni composites. The diffraction peaks correspond to the crystalline planes of (111), (200) and (220) of face-centered cubic nickel, respectively. No peak of graphene appears due to low content of graphene in the composites. There are no other nickel carbide peaks besides those of nickel, suggesting a stable interface without chemical reaction between graphene and nickel matrix. The Raman peaks of graphene are observed at ~1350, ~1582 and ~2700 cm-1 corresponding to D band, G band and 2D band (Fig.3b), respectively, which suggests that graphene is synthesized when the sucrose is more than 80 mg. No Raman scattering peaks appears for the G-Ni-1 sample, because carbon could be in the form of a solid solution in nickel matrix at the low carbon source content. As a result of the formation of solid solution, the nickel (111) peak of the G-Ni-1 sample shifts slightly to a lower angle towards. The G band is strong and symmetrical, and the defect-related D band is negligible for the G-Ni-3 sample, indicating the high-quality of graphene in the composite fabricated at sucrose of 240 mg. The I2D/IG of graphene is 0.31~0.42, suggesting that graphene is 4
multi-layered. The metal nickel of the composite was etched in 3 M HCl solution to observe graphene. Fig. 3c shows a TEM image of a graphene sheet with residual nickel, which suggests a good interfacial adhesion between graphene and nickel matrix. It is observed from Fig.3d that a four-layer graphene sheet overlaps with a six-layer graphene sheet at the edges with a ~9° relative rotation.
Fig. 3. (a) XRD patterns of pure nickel and the G-Ni composites with different graphene content; (b) Raman spectra of the G-Ni composites; (c) TEM image of an etched G-Ni composite; (d) TEM image of two multi-layer graphene sheets and corresponding SAED pattern. 3.2 Mechanical properties
5
Fig. 4. (a) The Vickers hardness and (b) the tensile strength of the samples; (c) and (d) SEM images and Raman spectra (insert) of the fracture surface of the composite. It can be seen from Fig.4 that the mechanical properties of G-Ni composites are substantially enhanced because of in-situ growth of graphene. The hardness and tensile strength reach 107.1 HV and 370 MPa for the G-Ni-3 sample, which are about 1.7 and 4.1 times that of pure Ni, respectively. Generally, graphene could contribute to the strength improvement by grain size refinement, load transfer and dislocation strengthening. Here the average grain size estimated by the Scherrer equation using XRD data is almost the same for all the samples. Hence, the grain refinement is not a major strengthening mechanism for the G-Ni composites. This also suggests that in-situ fabrication is significantly different from the ex-situ methods reported in the literature. Certainly, graphene can hinder the grain growth of nickel and thus result in grain refinement in ex-situ processing. In in-situ powder processing, however, carbon atoms are dissolved in nickel matrix when the sample is sintered at high temperature, and carbon atoms segregate from nickel matrix and graphene forms on the grain boundaries when the sample is cooled [10]. Therefore, no graphene appears on the 6
grain boundaries and impedes the grain growth during the recrystallization process of nickel. Many cone-shaped dimples with micrometer scale are observed on the fracture surface (Fig.4c), suggesting a typical ductile fracture. A large transparent graphene sheet tightly adhered on the fracture surface shows a good interfacial bonding between graphene and nickel matrix. The in-situ growth of graphene in nickel matrix offers well-contacted interfaces without foreign impurity between graphene and nickel matrix, which is beneficial to high load transfer from nickel matrix to graphene. It is clearly observed that a long graphene bundle was pulled out along the tensile direction. Hence, the enhanced mechanical properties of the G-Ni composites can be explained by the high load-transfer efficiency of graphene in the nickel matrix [11]. 4. Conclusions The G-Ni composites have been successfully fabricated on-step through in-situ growing graphene in bulk nickel using a powder metallurgy method. Multi-layer graphene in-situ grew and uniformly disperse in nickel. The in-situ fabricated composite exhibits the enhanced mechanical properties. The strengthening mechanism of in-situ grown graphene in the nickel matrix is primarily attributed to the load transfer effect. This versatile method will inspire the design and fabrication of graphene-metal composite for superior mechanical performance, because of its great advantages of uniform growth of graphene and sintering densification of the metal matrix in one-step. Acknowledgments 7
This work was supported by the National Natural Science Foundation of China (51741104). References [1] S. Feng, Q. Guo, Z. Li, G. Fan, Z. Li, D. Xiong, Y. Su, Z. Tan, J. Zhang, D. Zhang, Strengthening and toughening mechanisms in graphene-Al nanolaminated composite micro-pillars, Acta Mater. 125 (2017) 98-108. [2]Z. Hu, G. Tong, D. Lin, C. Chen, H. Guo, J. Xu, L. Zhou, Graphene-reinforced metal matrix nanocomposites-a review, Mater. Sci. Technol. 32 (2016) 930-953. [3]H. Luo, Y. Sui, J. Qi, Q. Meng, F. Wei, Y. He, Copper matrix composites enhanced by silver/reduced graphene oxide hybrids, Mater. Lett. 196 (2017) 354-357. [4]M. Rashad, F. Pan, M. Asif, Exploring mechanical behavior of Mg-6Zn alloy reinforced with graphene nanoplatelets, Mater. Sci. Eng. A 649 (2016) 263-269. [5]Y. Chen, X. Zhang, E. Liu, C. He, C. Shi, J. Li, P. Nash, N. Zhao, Fabrication of in-situ grown graphene reinforced Cu matrix composites, Sci. Rep. 6 (2016) 19363. [6] H. Yue, L. Yao, X. Gao, S. Zhang, E. Guo, H. Zhang, X. Lin, B. Wang, Effect of ball-milling and graphene contents on the mechanical properties and fracture mechanisms of graphene nanosheets reinforced copper matrix composites, J. Alloy. Compd. 691 (2017) 755-762. [7]J. Hwang, T. Yoon, S. H. Jin, J. Lee, T.-S. Kim, S. H. Hong, S. Jeon, Enhanced mechanical properties of graphene/copper nanocomposites using a molecular-level mixing process, Adv. Mater. 25 (2013) 6724-6729. 8
[8]S.F. Bartolucci, Joseph Paras, M. A. Rafiee, J. Rafiee, S. Lee, D. Kapoor, N. Koratkar, Graphene-aluminum nanocomposites, Mater. Sci. Eng. A 528 (2011) 7933-7937. [9] H. C. Lee, W.-W. Liu, S.-P. Chai, A. R. Mohamed, A. Aziz, C.-S. Khe, N. M. S. Hidayah, U. Hashim, Review of the synthesis, transfer, characterization and growth mechanisms of single and multilayer graphene, RSC Adv. 7 (2017) 15644-15693. [10] X. Li, W. Cai, L. Colombo, R. S. Ruoff, Evolution of graphene growth on Ni and Cu by carbon isotope labeling, Nano Lett. 9 (2009) 4268-4272. [11] C. Zhao, Enhanced strength in reduced graphene oxide/nickel composites prepared by molecular-level mixing for structural applications, Appl. Phys. A 118 (2015) 409-416.
9
Dear editor and reviewers,
We submit here a manuscript entitled “In-situ fabrication of graphene-nickel matrix composites” for your consideration as an article in Materials Letters. We believe that four aspects of this manuscript will make it interesting to general readers of Materials Letters.
Graphene-nickel composites have been fabricated by growing graphene in nickel.
In-situ grown graphene distributes uniformly in nickel serving as reinforcement.
The fabricated composites exhibit significantly improved mechanical properties.
This method has advantages of graphene growth and nickel sintering in one-step.
Thank you very much for your attention. Sincerely,
Jinlong Jiang.
10
S0167-577X(18)30395-1 https://doi.org/10.1016/j.matlet.2018.03.039 MLBLUE 24000
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
17 December 2017 23 February 2018 4 March 2018
Please cite this article as: J. Jiang, X. He, J. Du, X. Pang, H. Yang, Z. Wei, In-situ fabrication of graphene-nickel matrix composites, Materials Letters (2018), doi: https://doi.org/10.1016/j.matlet.2018.03.039
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
In-situ fabrication of graphene-nickel matrix composites Jinlong Jiang a,b,c , Xingxing Heb, Jinfang Dub, Xianjuan Pangc, Hua Yangb, Zhiqiang Weib a. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu, China b. Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, Gansu, China c. National United Engineering Laboratory for Advanced Bearing Tribology, Henan University of Science and Technology, Luoyang 471023, Henan, China Abstract: Graphene-nickel (G-Ni) matrix composites were fabricated through in-situ growing graphene in bulk nickel matrix using a powder metallurgy method. Sucrose as precursor of graphene was dispersed into nickel powders to grow graphene, avoiding a traditional dispersion process of graphene in metal matrix. Multi-layer graphene was synthesized in-situ in nickel matrix, meanwhile nickel matrix was densified at high temperature. The nickel matrix acts as support and catalyst of graphene, and graphene grow in-situ in nickel matrix serving as reinforcement. This in-situ growth method offers a homogeneous dispersion of graphene and well-contacted interfaces between graphene and nickel matrix, which provides a guarantee for high load transfer from nickel matrix to graphene. Keywords: graphene; metallic composites; in-situ fabrication; microstructure; mechanical properties
Corresponding author. Tel./fax: +86 931 2976040. E-mail address: [email protected]. 1
1. Introduction Graphene is an ideal nanostructured reinforcement for metal matrix composites because of its unique two dimensional structure and outstanding physical and mechanical properties [1, 2]. The great challenge for developing high performance graphene-metal composites is to disperse graphene into metal matrix uniformly. Many methods [3-7] have been developed to solve the aggregation problem of graphene caused by the strong van der Waals interactions and incompatibility between graphene and metal matrix. The ball-milling is an effective and practical technique to disperse graphene into the metal. However, it would inevitably introduce lots of structural defects in graphene as a result of severe deformation [6]. The melting and stirring method is not applicable to graphene-metal composites because the large density difference between graphene and metal causes graphene to easily float on the top of metal [7]. Also high melting temperature of metals easily triggers a serious interface reaction between graphene and metal matrix [8]. Although the liquid dispersion methods are flexible to solve the agglomeration problem of graphene, the residual groups from organic solvents could be introduced into the composites. In this paper, enlightened by the fact that the growth temperature and atmosphere conditions of graphene on nickel substrate are similar to those of a powder metallurgy sintering process of nickel matrix composite, we propose an in-situ fabrication of G-Ni composites by growing graphene in bulk nickel matrix using a facile powder metallurgy method. 2. Experimental 2
Nickel powders (10 g, 300 meshes) and sucrose (80, 160, 240, 320 mg) were mixed in 150 mL of deionized water. This powder mixture was stirred mechanically at 120 °C until water was entirely evaporated. Subsequently, the powder mixture was cold-compacted for 10 min in a metal mold at a pressure of 380 MPa. Finally, the green compact was sintered at 1100 °C for 40 min in a quartz tube furnace. The sintered process was conducted at a heating rate of 10 °C min-1, under a mixed H2/Ar atmosphere (H2 200 sccm, Ar 500 sccm) with a chamber pressure of 900 Pa. After sintering, the samples were cooled to room temperature at a rate of 10 °C min-1. 3．Results and discussion 3.1 Structure characterization
Fig. 1. A schematic diagram of the in-situ fabrication process of G-Ni composite. Fig.1 shows a schematic diagram of the in-situ fabrication process of the G-Ni composites. Different from the conventional powder metallurgy process, sucrose as precursor of graphene instead of graphene was dispersed into nickel powders. The graphene directly grew from a pressed green compact of nickel powders covered with sucrose at a high-temperature sintering process. The nickel matrix acts as support and catalyst of growth of graphene, and the in-situ grown graphene serve as the reinforcement of nickel matrix. It is seen from Fig. 2 that carbon signals from 3
graphene are very uniform, which proves that graphene distributes uniformly in nickel matrix. A dissolution-precipitation growth mechanism can explain the graphene growth on nickel [9].
Fig. 2. (a) SEM and optical (inset) images of the G-Ni composite and corresponding EDS mapping for (b) carbon and (c) nickel elements. Fig. 3a shows the XRD patterns of pure nickel and the G-Ni composites. The diffraction peaks correspond to the crystalline planes of (111), (200) and (220) of face-centered cubic nickel, respectively. No peak of graphene appears due to low content of graphene in the composites. There are no other nickel carbide peaks besides those of nickel, suggesting a stable interface without chemical reaction between graphene and nickel matrix. The Raman peaks of graphene are observed at ~1350, ~1582 and ~2700 cm-1 corresponding to D band, G band and 2D band (Fig.3b), respectively, which suggests that graphene is synthesized when the sucrose is more than 80 mg. No Raman scattering peaks appears for the G-Ni-1 sample, because carbon could be in the form of a solid solution in nickel matrix at the low carbon source content. As a result of the formation of solid solution, the nickel (111) peak of the G-Ni-1 sample shifts slightly to a lower angle towards. The G band is strong and symmetrical, and the defect-related D band is negligible for the G-Ni-3 sample, indicating the high-quality of graphene in the composite fabricated at sucrose of 240 mg. The I2D/IG of graphene is 0.31~0.42, suggesting that graphene is 4
multi-layered. The metal nickel of the composite was etched in 3 M HCl solution to observe graphene. Fig. 3c shows a TEM image of a graphene sheet with residual nickel, which suggests a good interfacial adhesion between graphene and nickel matrix. It is observed from Fig.3d that a four-layer graphene sheet overlaps with a six-layer graphene sheet at the edges with a ~9° relative rotation.
Fig. 3. (a) XRD patterns of pure nickel and the G-Ni composites with different graphene content; (b) Raman spectra of the G-Ni composites; (c) TEM image of an etched G-Ni composite; (d) TEM image of two multi-layer graphene sheets and corresponding SAED pattern. 3.2 Mechanical properties
5
Fig. 4. (a) The Vickers hardness and (b) the tensile strength of the samples; (c) and (d) SEM images and Raman spectra (insert) of the fracture surface of the composite. It can be seen from Fig.4 that the mechanical properties of G-Ni composites are substantially enhanced because of in-situ growth of graphene. The hardness and tensile strength reach 107.1 HV and 370 MPa for the G-Ni-3 sample, which are about 1.7 and 4.1 times that of pure Ni, respectively. Generally, graphene could contribute to the strength improvement by grain size refinement, load transfer and dislocation strengthening. Here the average grain size estimated by the Scherrer equation using XRD data is almost the same for all the samples. Hence, the grain refinement is not a major strengthening mechanism for the G-Ni composites. This also suggests that in-situ fabrication is significantly different from the ex-situ methods reported in the literature. Certainly, graphene can hinder the grain growth of nickel and thus result in grain refinement in ex-situ processing. In in-situ powder processing, however, carbon atoms are dissolved in nickel matrix when the sample is sintered at high temperature, and carbon atoms segregate from nickel matrix and graphene forms on the grain boundaries when the sample is cooled [10]. Therefore, no graphene appears on the 6
grain boundaries and impedes the grain growth during the recrystallization process of nickel. Many cone-shaped dimples with micrometer scale are observed on the fracture surface (Fig.4c), suggesting a typical ductile fracture. A large transparent graphene sheet tightly adhered on the fracture surface shows a good interfacial bonding between graphene and nickel matrix. The in-situ growth of graphene in nickel matrix offers well-contacted interfaces without foreign impurity between graphene and nickel matrix, which is beneficial to high load transfer from nickel matrix to graphene. It is clearly observed that a long graphene bundle was pulled out along the tensile direction. Hence, the enhanced mechanical properties of the G-Ni composites can be explained by the high load-transfer efficiency of graphene in the nickel matrix [11]. 4. Conclusions The G-Ni composites have been successfully fabricated on-step through in-situ growing graphene in bulk nickel using a powder metallurgy method. Multi-layer graphene in-situ grew and uniformly disperse in nickel. The in-situ fabricated composite exhibits the enhanced mechanical properties. The strengthening mechanism of in-situ grown graphene in the nickel matrix is primarily attributed to the load transfer effect. This versatile method will inspire the design and fabrication of graphene-metal composite for superior mechanical performance, because of its great advantages of uniform growth of graphene and sintering densification of the metal matrix in one-step. Acknowledgments 7
This work was supported by the National Natural Science Foundation of China (51741104). References [1] S. Feng, Q. Guo, Z. Li, G. Fan, Z. Li, D. Xiong, Y. Su, Z. Tan, J. Zhang, D. Zhang, Strengthening and toughening mechanisms in graphene-Al nanolaminated composite micro-pillars, Acta Mater. 125 (2017) 98-108. [2]Z. Hu, G. Tong, D. Lin, C. Chen, H. Guo, J. Xu, L. Zhou, Graphene-reinforced metal matrix nanocomposites-a review, Mater. Sci. Technol. 32 (2016) 930-953. [3]H. Luo, Y. Sui, J. Qi, Q. Meng, F. Wei, Y. He, Copper matrix composites enhanced by silver/reduced graphene oxide hybrids, Mater. Lett. 196 (2017) 354-357. [4]M. Rashad, F. Pan, M. Asif, Exploring mechanical behavior of Mg-6Zn alloy reinforced with graphene nanoplatelets, Mater. Sci. Eng. A 649 (2016) 263-269. [5]Y. Chen, X. Zhang, E. Liu, C. He, C. Shi, J. Li, P. Nash, N. Zhao, Fabrication of in-situ grown graphene reinforced Cu matrix composites, Sci. Rep. 6 (2016) 19363. [6] H. Yue, L. Yao, X. Gao, S. Zhang, E. Guo, H. Zhang, X. Lin, B. Wang, Effect of ball-milling and graphene contents on the mechanical properties and fracture mechanisms of graphene nanosheets reinforced copper matrix composites, J. Alloy. Compd. 691 (2017) 755-762. [7]J. Hwang, T. Yoon, S. H. Jin, J. Lee, T.-S. Kim, S. H. Hong, S. Jeon, Enhanced mechanical properties of graphene/copper nanocomposites using a molecular-level mixing process, Adv. Mater. 25 (2013) 6724-6729. 8
[8]S.F. Bartolucci, Joseph Paras, M. A. Rafiee, J. Rafiee, S. Lee, D. Kapoor, N. Koratkar, Graphene-aluminum nanocomposites, Mater. Sci. Eng. A 528 (2011) 7933-7937. [9] H. C. Lee, W.-W. Liu, S.-P. Chai, A. R. Mohamed, A. Aziz, C.-S. Khe, N. M. S. Hidayah, U. Hashim, Review of the synthesis, transfer, characterization and growth mechanisms of single and multilayer graphene, RSC Adv. 7 (2017) 15644-15693. [10] X. Li, W. Cai, L. Colombo, R. S. Ruoff, Evolution of graphene growth on Ni and Cu by carbon isotope labeling, Nano Lett. 9 (2009) 4268-4272. [11] C. Zhao, Enhanced strength in reduced graphene oxide/nickel composites prepared by molecular-level mixing for structural applications, Appl. Phys. A 118 (2015) 409-416.
9
Dear editor and reviewers,
We submit here a manuscript entitled “In-situ fabrication of graphene-nickel matrix composites” for your consideration as an article in Materials Letters. We believe that four aspects of this manuscript will make it interesting to general readers of Materials Letters.
Graphene-nickel composites have been fabricated by growing graphene in nickel.
In-situ grown graphene distributes uniformly in nickel serving as reinforcement.
The fabricated composites exhibit significantly improved mechanical properties.
This method has advantages of graphene growth and nickel sintering in one-step.
Thank you very much for your attention. Sincerely,
Jinlong Jiang.
10