Ultrahigh pressure consolidation (UHPC) of W-Cu composites

Abstract

Ultrahigh pressure consolidation was used to densify tungsten-copper (W -Cu) green compacts. The consolidation was carried out at temperatures rangingfrom 900 to 1400°C under pressures of 1'25 or 2.0 GPa for 10 min. The density measurements were carried out by Archimedes' method and the microstructure was characterised using SEM. Application of high pressure provides the driving force for the powder compacts to be consolidated to high density. However, the micrographs revealed there was an inhomogeneous distribution of Cu, segregation of Cu to the surface, and abnormal grain growth in some areas. These undesirable results are attributed to the immiscibility of Win Cu, presence of pressure gradients, temperature gradients, and powder agglomeration. Comparison of the densities obtained with the microstructure indicated that Archimedes’method may be unreliablefor small specimens, and larger specimens are requiredfor reliable measurement of densities.