Copper is a widely used electrical material owing to its excellent electrical and thermal conductivity, which makes it highly suitable for applications in electrical contacts and related components. However, its relatively low hardness, poor wear resistance, and limited mechanical strength restrict its use under demanding service conditions. To overcome these limitations, copper is frequently reinforced with hard ceramic particles such as SiC, resulting in Cu-based composites with improved mechanical performance. In conventional metal matrix composites (MMCs), enhancements in hardness and strength are typically accompanied by a reduction in electrical conductivity, thereby limiting their applicability in electrical systems. Functionally graded composites (FGCs) provide a promising strategy to address this challenge. By gradually varying the reinforcement content across the material, FGCs enable the outer layers of a component to be reinforced for enhanced hardness and wear resistance, while a copper-rich core preserves high electrical conductivity. This graded architecture allows for a property combination unattainable in uniformly reinforced MMCs. In this study, Cu-based FGCs reinforced with SiC were fabricated using high-energy ball milling (HEBM) followed by field-assisted sintering (FAST), with the aim of achieving a balance between surface hardness and core conductivity. Cu/SiC composite powders containing 5-20 vol% SiC were prepared by HEBM for 6 h and subsequently consolidated by FAST into graded structures. The final configuration consisted of a pure Cu core surrounded by symmetric layers containing 5, 10, 15, and 20 vol% SiC, each 0.5 mm thick, yielding sintered discs with a diameter of 40 mm and a thickness of 5 mm. The microstructure and phase composition of the composite powders were examined using light microscopy (LM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Particle size distribution (PSD) and specific surface area were determined via laser diffraction and gas adsorption techniques, respectively. Microhardness measurements were conducted to evaluate the influence of milling time and SiC contents. The LM and SEM analyses confirmed that after 6 h of milling, a uniform distribution of SiC particles and nearly spherical powder morphology were obtained. Particle evolution was influenced by both SiC fractions and milling duration. Microhardness results indicated a significant dependence on these parameters, with values reaching 339 HV0.01 at 20 vol% SiC. XRD analysis further revealed a pronounced influence of milling time on crystallite size, which decreased from ~300 nm to below 50 nm. The consolidated FGCs were subsequently characterized by LM, SEM, and XRD to assess microstructural uniformity, reinforcement distribution, and phase composition across the graded layers. Functional properties were evaluated through microhardness (HV1) and electrical conductivity measurements for each layer. Results demonstrated that microhardness increased progressively with SiC content up to 20 vol%, while electrical conductivity decreased accordingly. The copper-rich core retained conductivity in the range of 90-100% IACS, whereas the outer layers exhibited enhanced hardness due to increased reinforcement levels. Overall, the developed Cu/SiC-based FGCs successfully combine high surface hardness with excellent core conductivity, highlighting their strong potential for industrial applications in electrical contacts where both wear resistance and high conductivity are required.

Keywords: Functionally graded composites (FGCs), Cu/SiC, high-energy ball milling (HEBM), field-assisted sintering (FAST), advanced electrical contacts, tailored properties