Consolidation and properties of tungsten by spark plasma sintering and hot isostatic pressing

Abstract The fabrication of dense tungsten was attempted with the combination process of presintering by spark plasma sintering and final hot isostatic pressing. The specimens fabricated by spark plasma sintering (1500–1600 °C) of commercial powder exhibited a relative density above 90.4%. In the case of the post hot isostatic pressing at 1650 °C for 2 h, improved relative density in the range of 96.4% to 97.2% was obtained. X-ray diffractometry and X-ray photoelectron spectroscopy analysis indicated that the sintered specimen was composed mainly of tungsten, and the trace amounts of metallic tungsten are bound with oxygen due to the surface oxidation. Strength measurement was conducted by biaxial bending test using a piston-on-three balls. Maximum flexural strength of 761 MPa were obtained for tungsten consolidated by a combined process of spark plasma sintering and hot isostatic pressing. The strength increase is explained by the increase in relative density rather than the effect of particle size.