Shock Assisted Liquid Phase Consolidation of Nanostructured W-Ag Composites

In order to fabricate and to consolidate different compositions within the W-Ag powder systems and to obtain bulk nanostructured billets near to theoretical densities, nanoscale tungsten precursors we used, with grain sizes... [ view full abstract ]

In order to fabricate and to consolidate different compositions within the W-Ag powder systems and to obtain bulk nanostructured billets near to theoretical densities, nanoscale tungsten precursors we used, with grain sizes under 100nm. Conventional silver powders with grain size around 5µ were then added to the W 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 blended powders were consolidated to near the theoretical density. These investigations showed that the application of nanostructured W-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 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 depends 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 W-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 nanostructured composites together with the detail description of HEC technique.