Microstructure refinement in W–Y2O3 alloys via an improved hydrothermal synthesis method and low temperature sintering

Abstract

In order to prepare high performance oxide-dispersion-strengthened tungsten-based alloys, W–Y₂O₃ composite nanopowders were prepared using an improved hydrothermal synthesis method with the addition of the surfactant polyvinyl pyrrolidone (PVP). The resulting hydrothermally synthesized blue (NH₄)_XWO₃ compound is an excellent tungsten source to use to prepare ultrafine W–Y₂O₃ composite nanopowders with an average W grain size of only 15 nm. Then, low temperature sintering characteristics showed that the sintered W–Y₂O₃ alloys prepared using the hydrothermally synthesized blue (NH₄)_XWO₃ complex as the tungsten source possess refined W grains of about 200 nm, a relatively high density of 97.8%, well-dispersed Y₂O₃ particles (<150 nm), and thus a high hardness value of 732.6 ± 37.0 HV_0.2. It is worth noting that the alloys maintain a relatively high density as well as a fine grain size. Based on our results, the improved hydrothermal synthesis method with surfactant addition is a promising way by which to fabricate high performance oxide-dispersion-strengthened tungsten-based alloys with ultrafine grains.