Fabrication of ultrafine W-Cu composite powders and its sintering behavior

Abstract

Ultrafine W-Cu composite powders with various copper (Cu) contents (5, 20 and 40 wt.%) have been fabricated by a method consisting of a carbothermic pre-reduction step and a subsequent hydrogen reduction step. After roasting the mixture of ammonium tungstate ((NH4)10[H2W12O42]·xH2O) and copper nitrate trihydrate (Cu(NO3)2·3H2O), the mixture of CuWO4 and CuO (or WO3) was obtained. Subsequently, this mixture was pre-reduced by insufficient carbon black to generate the products containing W, Cu and a small amount of WO2 which was further reduced to W in the following hydrogen reduction process. Thus, the ultrafine W-Cu composite powders were successfully produced. After sintering the green compacts made of these powders at 1100 ℃, 1150 ℃, 1200 ℃ and 1250 ℃, respectively, the microstructure, relative densities, electric conductivity and thermal conductivity of the sintered alloys were measured. The experimental results indicated that the higher the sintering temperature is, the better the performance of alloys will be. Keywords: Composite powders, Relative density, Hardness, Thermal conductivity, Electric conductivity