Improved flexural strength of diamond/Cu–Fe composites with Cu–B–B 4 C coating

The interface between diamond and copper (Cu) alloy matrix in the composites significantly affects their mechanical properties. The functionalization of the diamond surface is of great potential for exploiting different advanced mechanical tools. In the present case, copper–boron–boron carbide (Cu–B–B₄C) composite coating was grown simultaneously on the whole surface of diamonds. Subsequently, the diamond particles were reinforced with copper–iron (Cu–Fe) matrix composites through powder metallurgy. The microstructural analysis demonstrated that the composite coatings were composed of two layers: the interior layers of B₄C and B as well as the exterior layer of Cu–B alloy. The bending strength of Cu–B–B₄C composite-coated diamond was determined to be 701 MPa at a sintering temperature of 800°C, which was nearly 27% higher compared to that (553 MPa) of uncoated diamond/Cu–Fe composites.