Keywords: nanostructures, oxide dispersion, tungsten alloys, ball milling, sintering, nanograins, nanograin stability, grain size, nanotechnology, compaction
Evolution of grain size in oxide dispersion strengthened tungsten alloys during their elaboration by ball milling and sintering
Oxide dispersion strengthened tungsten alloys have been elaborated from tungsten and yttrium powders by reactive ball milling, compaction and sintering. The present study focuses on the analyses of the nanostructure of the crystallites and second phases developed during ball milling and underlines the significant grain growth during sintering. The major causes of such an evolution are on the first hand, contamination by oxygen and cobalt during ball milling which lead to liquid state sintering and on the second hand, coarsening of the second phases. Numerous techniques were used, among which thin foil transmission electron microscopy of powder particles, so as to study the evolution of both the size and morphology of the crystallites and the second phases dispersion. At last, various ways of improvement of the elaboration process are suggested.