Microstructure Refinement in W-Y2O3 Alloy Fabricated by Wet Chemical Method with Surfactant Addition and Subsequent Spark Plasma Sintering

With the aim of preparing high performance oxide-dispersion-strengthened tungsten based alloys by powder metallurgy, the W-Y 2 O 3 composite nanopowder precursor was fabricated by an improved wet chemical method with anion surfactant sodium dodecyl sulfate (SDS) addition. It is found that the employment of SDS can dramatically decrease W grain size (about 40 nm) and improve the size uniformity. What's more, SDS addition can also remarkably improve the uniform dispersion of Y 2 O 3 particles during the synthesis process. For the alloy whose powder precursor was fabricated by traditional wet chemical method without SDS addition, only a few Y 2 O 3 dispersoids with size of approximate 10-50 nm distribute unevenly within tungsten grains. Nevertheless, for the sintered alloy whose powder precursor was produced by improved wet chemical method, the Y 2 O 3 dispersoids (about 2-10 nm in size) with near spherical shape are dispersed well within tungsten grains. Additionally, compared with the former, the alloy possesses smaller grain size (approximate 700 nm) and higher relative density (99.00%). And a Vickers microhardness value up to 600 Hv was also obtained for this alloy. Based on these results, the employment of SDS in traditional wet chemical method is a feasible way to fabricate high performance yttria-dispersion-strengthened tungsten based alloys.