Additive manufacturing of graphene-reinforced copper matrix composites produced via cold spray

Abstract

Graphene (Gr)-reinforced composites offer significant potential for enhanced thermal, mechanical, and functional performances, yet their fabrication via energy beam-based additive manufacturing (AM) is challenging due to the thermal sensitivity of Gr, the risk of agglomeration, and limitations of high-temperature processes. As a solution, Cu-1 wt% Gr deposits were successfully produced using cold spray additive manufacturing (CSAM), providing a solid-state route to fabricate dense 2D metal matrix composites (2DMMCs). The effects of Gr incorporation and gas temperature were systematically investigated on microstructural evolution, dynamic recrystallization, and functional properties. 2DMMCs properties were compared with pure Cu to isolate the effects of Gr reinforcement. The effect of microstructural homogenization induced by post-deposition heat-treatment was analysed on thermal, electrical and mechanical performances. Findings indicate that the presence of Gr alters how strain and thermal energy are distributed within the deposits, promoting heterogeneous microstructures and increasing microhardness. Higher gas temperature led to higher density and thermal conductivity. However, mechanical and electrical properties were moderately reduced due to Gr-induced stress concentrations and interparticle bonding limitations. Subsequent post-deposition annealing partially reduced bulk defects and led to enhanced thermal and electrical performance. Our findings demonstrate that CSAM enables the efficient production of Cu–Gr 2DMMCs. The structure–property relationships established in this work identify interfacial bonding and Gr distribution as the key factors governing composite performance, providing a foundation for future optimization of solid-state AM strategies for large scale 2DMMCs.