Abstract
2D nanomaterials offer unique functional properties when combined with metal powder feedstock, enabling advanced composites for engineering and energy applications1. Scalable fabrication of nanosheet-reinforced metal matrix composites (2DMMCs) remains challenging. In this study, we first exfoliate 2D materials using a solvent-free ball milling approach, using graphene and hexagonal boron nitride (hBN) as demonstrators, and then attach the resulting 2D nanoplatelets onto a wide range of metal powders, including copper (Cu), titanium (Ti-6Al-4V), aluminum (AlSi10Mg), and stainless steel (SS316L). To provide a mechanistic understanding of exfoliation, we use density functional theory (DFT) and discrete element method (DEM) simulations, offering new insights into the forces that drive nanosheet exfoliation. The resulting 2DMMC powders combine excellent scalability and effectiveness. After consolidation, titanium alloy/graphene systems reaching thermal conductivity values of 17 W·m⁻¹·K⁻¹, comparable or superior to previous reports. Finally, we showcase their printability, confirming compatibility with large-scale manufacturing techniques and highlighting their potential for next-generation thermal applications.
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All the data generated or analyzed during this study are included in this published article and its supplementary file.
References
Miracle, D. Metal matrix composites from science to technological significance. Compos. Sci. Technol. 65, 2526–2540 (2005).
Nicolosi, V. et al. Liquid exfoliation of layered materials. Science 340, 1226419 (2013).
Pham, P. V. et al. 2D heterostructures for ubiquitous electronics and optoelectronics: principles, opportunities, and challenges. Chem. Rev. 122, 6514–6613 (2022).
Pham, P. V. et al. Layer-by-layer thinning of two-dimensional materials. Chem. Soc. Rev. 53, 5190–5226 (2024).
Pham, P. V. et al. Transfer of 2D films: from imperfection to perfection. ACS Nano 18, 14841–14876 (2024).
Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation of layered materials. Science 331, 568–571 (2011).
Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation of graphite. Nat. Nanotechnol. 3, 563–568 (2008).
Koutsioukis, A. et al. Stable dispersion of graphene in water, promoted by high-yield, scalable exfoliation of graphite in natural aqueous extracts: the role of hydrophobic organic molecules. ACS Sustain Chem. Eng. 10, 12552 (2022).
Lyu, H. et al. Ball-milled carbon nanomaterials for energy and environmental applications. ACS Sustain. Chem. Eng. 5, 9568–9585 (2017). 11.
Welham, N. J., Berbenni, V. & Chapman, P. G. Effect of extended ball milling on graphite. J. Alloy. Compd. 349, 255–263 (2003).
Jeon, I.-Y. et al. Edge-carboxylated graphene nanosheets via ball milling. Proc. Natl. Acad. Sci. USA 109, 5588–5593 (2012).
Xing, T. et al. Disorder in ball-milled graphite revealed by Raman spectroscopy. Carbon 57, 515–519 (2013).
Zhao, W. et al. Preparation of graphene by exfoliation of graphite using wet ball milling. J. Mater. Chem. 20, 5817–5819 (2010).
León, V. et al. Few-layer graphenes from ball-milling of graphite with melamine. Chem. Commun. 47, 10936–10938 (2011).
Yang, L. et al. Glue-assisted grinding exfoliation of large-size 2D materials. Mater. Today 51, 145–154 (2021).
Shi, D. et al. Ultrasonic-ball milling: a novel strategy to prepare large-size ultrathin 2D materials. Small 16, 1906734 (2020).
Zhou, Y. et al. Viscous solvent-assisted planetary ball milling for the scalable production of large ultrathin two-dimensional materials. ACS Nano 16, 10179–10187 (2022).
Wang, Z. et al. Scalable high-yield exfoliation for monolayer nanosheets. Nat. Commun. 14, 236 (2023).
Liu, X. Ingang et al. A review on mechanochemistry: approaching advanced energy materials with greener force. Adv. Mater. 34, 210832 (2022).
Raabe, D. The materials science behind sustainable metals and alloys. Chem. Rev. 123, 2436–2608 (2023).
Raabe, D., Tasan, C. C. & Olivetti, E. A. Strategies for sustainable metals production. Nature 575, 64–74 (2019).
George, E. P., Raabe, D. & Ritchie, R. O. High-entropy alloys. Nat. Rev. Mater. 4, 515–534 (2019).
Wang, H. et al. Thermal transfer in graphene-interfaced materials: contact resistance and interface engineering. ACS Appl. Mater. Interfaces 5, 2599–2603 (2013). 7.
Chen, D. et al. Graphene-reinforced metal matrix composites: fabrication, properties, and challenges. Int. J. Adv. Manuf. Technol. 125, 2925–2965 (2023).
Mussatto, A., Ahad, I. U., Mousavian, R. T., Delaure, Y. & Brabazon, D. Eng. Rep. 3, e12330 (2021).
Mussatto, A. et al. Advanced production routes for metal matrix composites. Eng. Rep. 3, 12330 (2020).
Sharma Kumar, D., Mahant, D. & Upadhyay, G. Manufacturing of metal matrix composites: a state of review. Mater. Today.: Proc. 26, 506–519 (2020).
Wang, W. et al. Measurement of the cleavage energy of graphite. Nat. Commun. 6, 7853 (2015).
Jung, J. H., Park, C. H. & Ihm, J. A rigorous method of calculating exfoliation energies from first principles. Nano Lett. 18, 2759–2765 (2018).
Gou, D. et al. DEM modelling of particle fragmentation during compaction of particles. Powder Technol. 398, 117073 (2022).
Naclerio, A. E. & Kidambi, P. R. A review of scalable hexagonal boron nitride (h-BN) synthesis for present and future applications. Adv. Mater. 35, 2207374 (2023).
Huang, C. et al. Stable colloidal boron nitride nanosheet dispersion and its potential application in catalysis. J. Mater. Chem. A 1, 12192–12197 (2013).
Ghosh, A. et al. Liquid exfoliation of hexagonal boron nitride. J. Mater. Eng. Perform. 33, 5364–5379 (2024).
Singh, B. et al. Nanostructured boron nitride with high water dispersibility for boron neutron capture therapy. Sci. Rep. 6, 35535 (2016).
Eledath, A. N., Poulose, A. E. & Muthukrishnan, A. Synthesis of few-layer graphene by ball-milling for oxygen reduction: kinetics and mechanistic insights. ACS Appl. Eng. Mater. 1, 2304–2314 (2023).
Blees, M. K. et al. Graphene kirigami. Nature 524, 204–207 (2015).
Dontsova, E. & Traian, D. Nanomechanics of twisted mono-and few-layer graphene nanoribbons. J. Phys. Chem. Lett. 4, 2010–2014 (2013).
Wei, Y. et al. Bending rigidity and Gaussian bending stiffness of single-layered graphene. Nano Lett. 13, 26–30 (2013).
Hu, T. et al. Quantifying the rigidity of 2D carbides (MXenes). Phys. Chem. Chem. Phys. 22, 2115–2121 (2020).
Suryanarayana, C. Mechanical alloying and milling. Prog. Mater. Sci. 46, 1–184 (2001).
Benjamin, J. S. & Volin, T. E. The mechanism of mechanical alloying. Metall. Trans. 5, 1929–1934 (1974).
Lee, H. et al. Review on properties, physics, and fabrication of two-dimensional material-based metal-matrix composites (2DMMCs) for heat transfer systems. Renew. Sust. Energy Rev. 217, 115700 (2025).
Lee, H. et al. Characterization of thermal properties of ball-milled copper-graphene powder as feedstock for additive manufacturing. Powder Technol. 121423 (2025).
Yan, Q. et al. Simultaneously improving mechanical, thermal, and anti-wear properties of Ti alloys using 3D-networked graphene as reinforcement. Carbon 213, 118152 (2023).
Gürbüz, M., Tuğba, M. & Pınar, U. Mechanical, wear and thermal behaviors of graphene reinforced titanium composites. Met. Mater. Int. 27, 744–752 (2021).
Yang, W.-Z. et al. Thermal and mechanical properties of graphene–titanium composites synthesized by microwave sintering. Acta Metall. Sin. (Engl. Lett.) 29, 707–713 (2016).
Zheng, H. & Jaganandham, K. Thermal conductivity and interface thermal conductance in composites of titanium with graphene platelets. J. heat. Transf. 136, 061301 (2014).
Wang, J. et al. Electrochemical depositing rGO-Ti-rGO heterogeneous substrates with higher thermal conductivity and heat transfer performance compared to pure Ti. Nanotechnology 28, 075703 (2017).
Liu, J. et al. Microstructure and mechanical properties of graphene oxide-reinforced titanium matrix composites synthesized by hot-pressed sintering. Nanoscale Res. Lett. 14, 114 (2019).
Gustafsson, S. E. Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials. Rev. Sci. Instrum. 62, 797–804 (1991).
Gustavsson, M., Karawacki, E. & Gustafsson, S. E. Thermal conductivity, thermal diffusivity, and specific heat of thin samples from transient measurements with hot disk sensors. Rev. Sci. Instrum. 65, 3856–3859 (1994).
Acknowledgements
V.N. wishes to thank the support of the SFI-funded AMBER research center, and the SFI Frontiers for the Future award (Grant Nos. 12/RC/2278_P2 and 20/FFP-A/8950, respectively). Furthermore, V.N. and A.K. wish to thank the support of the EIC Pathfinder ThermoDust project (project number 101046835). I.M.O. and V.N. acknowledge support from the European Union’s Horizon 2020 research and innovation program under Agreement No. 956813. S.R., R.L and S.Y. acknowledge support from the EIC Pathfinder ThermoDust project (Project No. 101046835). A.S. acknowledges support from Science Foundation Ireland (18/EPSRC-CDT/3581) and the Engineering and Physical Sciences Research Council (EP/S023259/1). J.M.M. thanks the Spanish Government’s Generation D initiative, promoted by Red.es, an organization attached to the Ministry for Digital Transformation and the Civil Service, for the attraction and retention of talent through grants and training contracts, financed by the Recovery, Transformation and Resilience Plan through the European Union’s Next Generation funds. Furthermore, V.N. and X.G. wish to thank the Advanced Microscopy Laboratory (AML) in CRANN for the provision of their facilities and thank Clive Downing for optimizing the microscope.
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R.L. and V.N. conceived and supervised the overall project. A.K. designed and performed the experiments, analyzed the data, interpreted the results, and drafted the manuscript. S.R. assisted with ball milling experiments and data analysis. R.C. and S.D.P. developed and executed the computational model supporting the experimental work. I.M.O. and X.G. performed TEM characterization and analyzed the corresponding data. A.R. performed materials characterization, including measurements of the surface energy and particle size distribution, and Y.X. carried out the SPS methodology. A.S. conducted BSD measurements. J.M.M. performed AFM measurements. H.L. and W.W.W. performed thermal conductivity measurements and contributed to their interpretation. J.C. and S.Y. contributed to discussions on experimental design and results. All authors contributed to writing, reviewed, and corrected the final manuscript, and approved its submission.
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The authors declare no competing interests. V.N. is an Associate Editor of npj 2D Materials and Applications but was not involved in the peer review of this article and had no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to another journal editor.
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Koutsioukis, A., Ruan, S., Cabello, R. et al. Sustainable, solvent-free exfoliation of 2D materials for thermally conductive metal powder coatings. npj 2D Mater Appl (2026). https://doi.org/10.1038/s41699-026-00680-7
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DOI: https://doi.org/10.1038/s41699-026-00680-7
