Strengthening mechanisms of Axially bi-Continuous Graphene/Nickel (ACGN) Composites for Breaking the Strength-Ductility Trade-off Condition

Graphene, a two-dimensional carbon material, is ultra-strong, flexible, and lightweight. These mechanical advantages can be combined with conventional metal to manufacture graphene-metal composites with enhanced mechanical performance. This project will achieve a fundamental understanding of the strengthening mechanisms of such composites by developing and utilizing bi-continuous graphene-nickel composites as a model. The results of this project will also guide the development of new theoretical models and innovative designs of graphene-based composites. High-performance composites, characterized by both strength and deformability, are relevant to a wide range of applications, including automotive/aerospace composites, sports equipment, protective armor, and high-strength cables. This project will integrate research and engineering training opportunities by fostering interdisciplinary research, education, and outreach opportunities across individuals from K-12 to undergraduate and graduate students. This project aims to deepen our understanding of the deformation mechanisms in axially bi-continuous graphene-metal composites. Graphene (Gr) offers excellent mechanical strength far beyond conventional metal and, therefore, is often dispersed in a metal matrix to develop macroscopic Gr-enhanced metal matrix composites for structural applications. However, such composites suffer from the intrinsic trade-off between strength and ductility due to weak Gr-metal interfaces. In this work, fine nickel wires coated by axially continuous graphene structures are used to break the intrinsic trade-off and achieve excellent combined strength and ductility. However, the exact mechanism(s) responsible for the observed enhancements are not well understood mainly due to the complex coupling of various size-dependent strengthening mechanisms. This project will reveal the underlying mechanisms by developing and utilizing new laser-based material processes and microdevice-based characterization methods. This project will provide valuable scientific knowledge on the intricate relationship between graphene structures, grains, and dislocations in such bi-continuous composites and their effect on mechanical behavior. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.