The study on low temperature sintering of nano-tungsten powders

Ultrafine grain tungsten is a promising candidate for plasma facing component applications in future fusion reactors. The conventional press-and-sinter powder metallurgy method is a preferred route for producing ultrafine grain tungsten from nanosize tungsten powders. However, controlling grain growth, while simultaneously attempting to achieve maximum densification, has been a challenge for making UGF tungsten by sintering. In this study, the effect of processing parameters on the densification and grain growth of nano-W powders was investigated. Near-fully densified tungsten was obtained at sintering temperatures between 1100 and 1300 degrees C, and both Ar and H-2 sintering atmospheres were investigated. The Ar sintering atmosphere was determined to more favorably promote densification and minimize grain growth. The nanosized tungsten powder compacts were subjected to reduction in H-2 as a part of the sintering cycle. The reduction temperature was found to have significant effects on the sintering of nano-W powder, primarily as a result of grain coarsening, which was seen at temperatures as low as 700 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.