Effects of processing parameters of tungsten-copper composites

Fabrication of net-shape tungsten-copper (W-Cu) composites has attracted more attention in recent years due to its good performance for wide applications. In this research, W-Cu composite including 20 wt.%, 25 wt.% or 30 wt.% Cu. was produced by powder metallurgy technique using wet mixtures of elemental powders. Cold compaction was carried out under pressures from 300 to 1200 MPa, while sintering was achieved in vacuum at 1400 degrees C for 1 h, and 2 h. The particle size and shape of powders, as well as the microstructure after wet mixing, compaction, and sintering were investigated by using SEM. Wet mixed powders were proved to be homogeneous, and the copper flake particles were found semi-coated by fine spherical tungsten particles. The relative green and the as-sintered densities were found to increase with increasing compaction pressure and copper content After sintering, the composite revealed homogeneous structure. The relative as-sintered density was found to increase with sintering time. Tungsten-copper composite compacted under 1200 MPa and sintered at 1400 degrees C for 2 h exhibited the highest relative sintered density. hardness, and compression strength. Also, it exhibited the lowest electrical resistivity and coefficient of thermal expansion. (C) 2012 Elsevier Ltd. All rights reserved.