Synthesis and characterization of ultrafine tungsten samples produced by plasma-activated sintering

Plasma-activated sintering was used to densify micron-size tungsten powders to obtain bulk samples. This sintering technique offers the capability of producing bulk samples having a very high density. The average size of the starting tungsten powder particles was 4·61 µm. Using a combination of pressure and temperature, during sintering, 11 different samples were prepared. The bulk samples were produced over a range of pressure from 41 to 61 MPa. At selected pressure levels of 47–61 MPa, the bulk samples produced were sintered at different temperatures. Microstructural observations and density measurements provide evidence for the presence of porosity at both the microscopic and macroscopic levels. The extrinsic influence of processing parameters used during sintering, namely, pressure and temperature, on microstructural development to include the presence, size and distribution of porosity, density, microhardness, nanohardness and stiffness is presented and discussed.