Properties of Ultrafine-Grained Tungsten Prepared by Ball Milling and Spark Plasma Sintering

Abstract

Tungsten is currently considered as the most suitable plasma facing material for the first wall of a nuclear fusion reactor. First wall will be subjected to harsh conditions that will gradually deteriorate properties of the wall material. Some studies point out that fine-grained tungsten could be more resistant to the structure and property changes than coarse-grained tungsten. However, tailoring of tungsten microstructure is very laborious. Due to its high melting point, tungsten is very often processed mechanically and subsequently sintered into a compact body. In this study, preparation of ultrafine-grained tungsten by mechanical processing in a planetary ball mill was examined. Three types of tungsten samples were compared. One was made from coarse grained tungsten powder consolidated by SPS (spark plasma sintering). Other two samples were prepared from the powder processed in a planetary ball mill with and without addition of Y2O3. After ball milling, the powders were consolidated by SPS, i.e. fast sintering process that allows preserving fine-grained structure of the powder material. Properties of the samples such as hardness and thermal conductivity were examined and correlated with the processing history and microstructure.