Fabrication, microstructure, and properties of (NbTi)C particle-reinforced copper matrix composites

Abstract

(NbTi)C particles were prepared by mechanical alloying combined with heat treatment, and Cu matrix composites with different (NbTi)C contents were fabricated by fast hot-press sintering under a low-vacuum environment (10 Pa). The microstructure and structural characteristics of the composites were characterized, and their physical and mechanical properties were evaluated. The results show that, with increasing (NbTi)C particle content, the hardness gradually increased, the ultimate tensile strength first increased and then decreased, whereas the elongation, electrical conductivity, and thermal conductivity gradually decreased. When the (NbTi)C content was 5 wt%, the ultimate tensile strength reached 363.19 MPa, which was 28.8% higher than that of pure Cu, while the room-temperature thermal conductivity remained above 280 W·m⁻¹·K⁻¹. The strengthening of the composites was mainly attributed to grain refinement, particle strengthening, and load transfer, whereas the decreases in electrical and thermal conductivities were associated with enhanced electron and phonon scattering at particles, grain boundaries, and interfaces. These results indicate that an appropriate (NbTi)C content can improve the mechanical properties of Cu while maintaining acceptable electrical and thermal conductivities. These findings provide a theoretical basis for designing Cu matrix composites with a high-strength and high-conductivity combination.