The study on the microwave sintering of tungsten at relatively low temperature

Tungsten and its alloys have to be of high density and good performance in the application for plasma facing materials in fusion reactors and for target materials in spallation neutron sources. In this paper the relatively high density tungsten was fabricated by microwave sintering at low temperatures (1673-1773 K) in a short time (30 min) using the ball milled micrometer and nanometer powders without any sintering-assistant additives. The density of the microwave-sintered samples increases with sintering temperature. The grain size can be controlled to be smaller than 1 μm and the thermal conductivity can reach 140 W/mK at room temperature when the WC ball milled nanometer tungsten powders were used. However, due to the introduction of some impurity phases during ball milling process, the thermal conductivity of the W samples microwave-sintered from the steel-ball milled powders is only about 50 W/mK at room temperature, even though these samples have higher relative density.