Synthesis and consolidation of W-Cu composite powders with silver addition

Homogeneous and nanostructured W-19 wt.%Cu-1 wt.%Ag and W-10 wt.%Cu-10 wt.%Ag composite powders were prepared via a chemical precipitation method, with the aim of surveying the effect of silver on the properties of tungsten-copper composites. For this purpose, ammonium metatungstate, copper nitrate and silver nitrate with predetermined weight proportion were separately dissolved in distilled water. Furthermore, W-20 wt.%Cu composite powders were provided for comparison. The initial precipitates were obtained by reacting a mixture of the mentioned solutions under certain pH and temperature. The precursor precipitates were then washed, dried, and calcined in air to form oxide powders. In the next step, the reduction was carried out in hydrogen atmosphere to convert them into the final nanocomposite powders. The resulting powders were evaluated using X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM) techniques. The effect of sintering temperature was investigated on densification and hardness of the powders compacts. The results showed that at all sintering temperatures, by increasing in the amount of silver, powders showed better sinterability compared to W-20 wt.%Cu powders. Maximum relative densities of 97.7%, 98.2% and 99.6% were achieved for W-20 wt.%Cu, W-19 wt.%Cu-1 wt.%Ag and W-10 wt.%Cu-10 wt.%Ag compacts sintered at 1200 degrees C, respectively. Moreover, maximum hardness of 359, 349 and 255 Vickers were resulted for W-20 wt.%Cu, W-19 wt.%Cu-1 wt.%Ag and W-10 wt.%Cu-10 wt.%Ag compacts sintered at 1200 degrees C, respectively. (C) 2011 Elsevier Ltd. All rights reserved.