Fabrication and Characterization of Cu–B₄C Metal Matrix Composite by Powder Metallurgy: Effect of B₄C on Microstructure, Mechanical Properties and Electrical Conductivity

Abstract

Boron carbide-reinforced copper metal matrix composites have been the subject of broad research because of their good mechanical, electrical and tribological properties. In the present research, Cu–B₄C composites containing 5, 10 and 15 wt% of B₄C have been fabricated by cold powder compaction followed by conventional sintering at 900 °C for 1 h under argon atmosphere. The fabricated composites are characterized by X-ray diffraction, optical microscopy and field emission scanning electron microscopy (FESEM). From microscopic study, we have found that B₄C particles are homogeneously distributed in the copper matrix and there is good compatibility between B₄C and Cu. The microstructure analyzed by FESEM shows that the interface between Cu matrix and B₄C is clean and no interfacial product is formed. The effect of B₄C particles and their weight fraction on microstructure, mechanical properties and electrical conductivity is also studied. The Vickers hardness value increases with increasing weight percentage of boron carbide in Cu matrix. The hardness value increases from 38 VHN for pure copper to 79 VHN for Cu-15 wt% B₄C metal matrix composite (MMC). A maximum relative density of 82% is achieved for Cu-5 wt% B₄C MMC. The maximum compressive strength of 315 MPa is achieved for Cu-15 wt% B₄C MMC. The electrical conductivity of pure Cu is found to be 4.5 × 10⁶ S/m, and it decreases to 1.92 × 10⁶, 0.75 × 10⁶ and 0.32 × 10⁶ S/m for Cu-5 wt% B₄C, Cu-10 wt% B₄C and Cu-15 wt% B₄C MMCs, respectively.