THE EFFECT OF TUNGSTEN PARTICLE-SIZE ON THE PROCESSING AND PROPERTIESOF INFILTRATED W-CU COMPACTS

Three tungsten powders with average particle sizes of 8.7, 23.2, and 6 5.2 mu m were used to make W-15Cu compacts. The compacting pressure an d sintering temperature were adjusted for each powder to attain the de sired skeleton density. Sintered skeletons were then infiltrated with oxygen-free copper at 1200 degrees C in hydrogen and in vacuum. Result s showed that as the tungsten particle size decreased, higher compacti ng pressures and sintering temperatures were required for the same des ired skeleton density. The processing parameters and the tungsten part icle size caused variations in the amount of closed pores and the W-W contiguity, which in turn resulted in different infiltrated densities and resistivities. Direct infiltration on green compacts was also exam ined, and higher infiltration densities and lower electrical resistivi ties were obtained compared to those obtained by infiltrating sintered compacts. These results are discussed based on infiltrated density, d ifferences in microstructure, and the W-W contiguity.