An experimental investigation on the W–Cu composites

Fabrication of tungsten–copper net-shapes has become an important issue in recent years due to their unique properties which make them suitable for a wide variety of applications. In this investigation, W–Cu composite powders containing 20 wt.% and 30 wt.% Cu were processed by powder metallurgy technique using two types of prepared powders, namely, Cu-coated tungsten and mixtures of elemental powders. The coating method of tungsten powders was carried out using electroless coating technique. The investigated powders were cold compacted and sintered in vacuum at two sintering temperatures, 1250 °C and 1400 °C.The results show that the Cu-coated compacts have higher relative green densities than those of admixed ones for each copper content and compaction pressure, which means that the coated powders have greater compressibility than the uncoated ones. The relative green density increases with increasing compaction pressure and copper content. After sintering, the composites fabricated from uncoated powders show inhomogeneous structure due to formation of large globules of copper and tungsten agglomerates, while the structure of coated tungsten composites reveals the existence of copper within the tungsten grains, forming uniform interconnected structure. In general, composites made from Cu-coated tungsten powders exhibited higher density, hardness, compression strength, and electrical conductivity than those of composites made from admixed elemental powders. However, coefficient of thermal expansion and electrical resistivity of Cu-coated composites showed lower values.