Effect of tungsten carbide particles on microstructure and mechanical properties of Cu alloy composite bit matrix

Copper alloy composite bit matrix was prepared by pressureless vacuum infiltration, using at least one of the three kinds of tungsten carbide particles, for example, irregular cast tungsten carbide, monocrystalline tungsten carbide and sintered reduced tungsten carbide particles. The effects of powder particle morphology, particle size and mass fraction of tungsten carbide on the microstructure and mechanical properties of copper alloy composite were investigated by means of scanning electron microscopy, X-ray diffraction and abrasive wear test in detail. The results show that tungsten carbide morphology and particle size have obvious effects on the mechanical properties of copper alloy composites. Cast tungsten carbide partially dissolved in the copper alloy binding phase, and layers of Cu0.3W0.5Ni0.1Mn0.1C phase with a thickness of around 8–15 μm were formed on the edge of the cast tungsten carbide. When 45% irregular crushed fine cast tungsten carbide and 15% monocrystalline cast tungsten carbide were used as the skeleton, satisfactory comprehensive performance of the reinforced copper alloy composite bit matrix was obtained, with the bending strength, impact toughness and hardness reaching 1048 MPa, 4.95 J/cm2 and 43.6 HRC, respectively. The main wear mechanism was that the tungsten carbide particles firstly protruded from the friction surface after the copper alloy matrix was worn, and then peeled off from the matrix when further wear occurred.