Effect of Chromium Initial State on Microstructure and Properties of Graphene‐Reinforced Copper Matrix Composites

Graphene is widely used to reinforce copper composites, yet weak interfaces, inefficient stress transfer, and graphene aggregation limit practical performance. Matrix alloying serves as an effective strategy to enhance interfacial bonding; however, the impact of the initial phase state of alloying elements (prealloyed solid solution vs. mechanical mixed powder) on the microstructure and macroscopic properties of composites remains poorly understood. This study employed ball milling and hot pressing/sintering processes to prepare composites with varying graphene contents (0–1  wt.%) using either prealloyed Cu‐2%Cr powder (GA group) or mechanically mixed pure Cu/Cr powder (GM group). Results demonstrated that in the GA group, chromium was uniformly dissolved at the atomic level, enabling superior graphene dispersion with dense interfacial bonding; conversely, in the GM group, chromium existed as micron‐sized discrete particles, leading to poor graphene dispersion. The GA group exhibited significantly better mechanical and electrical properties than the GM group, showing average increases in microhardness and compressive strength by approximately 12.6% and 12.4%, respectively, alongside an 11.1% reduction in resistivity. Compressive strength peaks at 723 MPa (0.5 wt.% graphene) and drops to 207 MPa at 1.0 wt.%. Excessive graphene induces stress concentration and brittle fracture under tight interfaces, revealing strong bonding’s double‐edged sword effect.