Study On Densification Process And Mechanical Properties Of W-Cu Composites

WCu composites have been used widely in the fields of electrical materials,electron,war industry and spaceflight due to their high strength and hardness, good electrical and erosion resistance. However, because of the mutual insolubility between W and Cu, it is difficult to get WCu materials with high relative density by traditional methods of infiltration of a tungsten skeleton with liquid copper and liquid phase sintering. In this paper, a new method to make W-Cu composite with nearly 100% of relatively density has been put forward. That is mixing, compacting, liquid phase sintering and hot hydrostatic extrusion at certain temperature. The fabricated WCu composite is fully densified, and fine microstructure and good mechanical properties can be obtained.In the dissertation, the well-proportioned W-Cu powders are obtained by mechanical milling in short time at low speed. The cold-pressed compacts have been made of such WCu powders, and it is found that the pressure force and loading speed have important effects on the relative density of the compacts.After liquid phase sintering, the WCu composites have been deformed by hot hydrostatic extrusion and subsequent hot extrusion, during which the plastic deformation of tungsten particle is not obvious. The change of conductivity and hardness of WCu composite after deformation has been investigated. The results show that the hardness is increased greatly, however, the conductivity is decreased.The tensile test of WCu composite has been done and the effects of sintering temperature, extrusion deformation on the plasticity of WCu material have been investigated. Meanwhile, the tensile fracture surface is analyzed which indicates that the fracture mechanism is the intergranular fracture of tungsten-copper phase interface and transgranular fracture of copper phase.