Fabrication and characterization of nanocrystalline ODS-W via a dissolution-precipitation process. (April 2019) - Wang, R.
Abstract: In this paper, high density nanocrystalline W with uniform dispersion of nanosized oxide particles was fabricated via a dissolution-precipitation process by well controlled high-energy ball milling of the raw powder materials of Y2 O3, Ti and W and the subsequent spark plasma sintering (SPS). XRD and TEM analysis revealed that the Y2 O3 and Ti were dissolved in W matrix during the high-energy ball milling and the Y2 Ti2 O7 particles were precipitated in the SPS process, resulting in the refinement in both W grains and oxide particles. The average grain size of W is 67 nm. The average size of particles in grain interior and at grain boundaries is 8.5 nm and 16.4 nm, respectively. The Vickers microhardness of such a nanostructured W alloy is as high as 1441 Hv, which is 2–3 times that of the ever reported W alloys. Such a dissolution-precipitation process offers a general pathway for manufacturing nanocrystalline refractory metals with dispersion of nanoscale oxides in a controllable manner. Highlights: A novel powder metallurgy approach to fabricate high density nanostructured tungsten based alloys. A WYT alloy contains nanosized tungsten grains (~67 nm) and nano oxide particles (~10 nm). An unprecedented high Vickers microhardness of ~1441 Hv has been achieved. The refining mechanisms include molecular-level dissolution and precipitation.