Enhancement of mechanical properties and fatigue performance of pure copper through GP and TaC reinforcements in metal matrix composites

Pure copper (Cu) and its composites are widely utilized in electrical, thermal, and structural applications due to their high conductivity and mechanical properties. However, improving fatigue resistance is essential for their long-term reliability. This study examines the low-cycle fatigue (LCF) and fatigue crack growth behavior of pure Cu, and a Cu-based metal matrix composite (MMC) reinforced with graphite (GP) and tantalum carbide (TaC). The Cu-GP-TaC MMC was fabricated by stir casting with a composition of 80% Cu, 10 % GP, and 10 % TaC by volume. Comparative mechanical assessments, including tensile testing, LCF analysis, and fatigue crack growth rate (FCGR) evaluation, reveal superior fatigue performance of the composite. EBSD characterization further confirms significant grain refinement, weakened texture intensity, and a predominance of high-angle grain boundaries (15°–65°) in the composite compared with pure Cu, all of which contribute to improved strength and fatigue resistance. The Cu-GP-TaC MMC exhibits higher tensile strength, enhanced strain life, and improved fatigue resistance across strain amplitudes (0.6 %–1.2 %) compared to pure Cu. S-N curve analysis indicates increased fatigue life and superior cyclic stress distribution. The composite also demonstrates greater strain hardening and higher plastic strain energy density at half-life cycles, contributing to an extended transition life. FCGR analysis confirms enhanced resistance to crack propagation under cyclic loading. Scanning electron microscopy (SEM) fractography reveals reduced crack initiation and propagation, attributed to the reinforcement’s strengthening effect. These findings highlight the Cu-GP-TaC MMC’s potential for high-performance structural applications, fatigue-resistant electrical contacts, and thermal management systems requiring enhanced mechanical reliability.