Liquid Phase Shock Assisted Synthesis and Consolidation of Nanostructured W-Ag and Ta-Ag Composites

In order to fabricate and to consolidate different compositions within the W-Ag and Ta-Ag powder systems and to obtain bulk nanostructured billets near to theoretical densities, nanoscale tungsten and tantalum precursors we used, with grain sizes 100 and 80nm respectively. Conventional silver powders with grain size around 5µ were then added to the W and Ta matrices. The temperature of heating and loading during the processing ranged from below to above the melting point of silver and up to 10000C. The intensity of loading was under 10GPa. Using Hot Explosive consolidation technology several compositions of nanostructured mixtures of W-Ag and Ta-Ag blended powders were consolidated to near the theoretical density. These investigations showed that the application of nanostructured W(Ta)-Ag blends of powders, followed by their explosive consolidation at near to the melting point of silver preserved the nanoscale of the grains of W and Ta and enabled the fabrication of cylindrical billets with density near to the theoretical values without visible coarsening. The consolidated samples were characterized with good integrity and improved physical and mechanical properties. The structure and characteristics of the obtained samples depend on the phase content, distribution of phases and processing parameters during explosive synthesis and consolidation. Additionally, we observed that the electrical properties (resistance and dependence of the susceptibility) of the consolidated Ta-Ag composites were dependent upon the phase content and the density of the consolidated samples. It also observed that the CTE of the nanostructured W-Ag composites was improved and that the microstructures showed better stability in comparison with existing W-Cu and AlSiC materials. In this paper we present and discuss the processing of the precursors and the fabrication of W-Ag and Ta-Ag nanostructured composites together with the detail description of HEC technique.