High-dense nanocrystalline W-based alloy prepared by hot isostatic pressing with uniform microstructure, ultrahigh hardness and good thermal stability

High-density uniform microstructure nanocrystalline W-10wt.% Cr-5wt.% Y (W-10Cr-5Y) alloy with an average grain size of 85 nm and a relative density of 99.8% was successfully prepared. W-Cr-Y alloys with different amounts of second-phase particles were prepared by high-energy ball milling and hot isostatic pressing technology. The effects of composition design, ball milling parameters, and sintering parameters on the microstructure of W-Cr-Y alloys were studied. A feasible technology for controlling the synthesis of high-density nanocrystalline W-based alloys has been proposed. The microstructure analysis of nanocrystalline W-10Cr-5Y alloy shows that there are two types of doping in the second phase: intergranular doping and intragranular doping. The “uniform distribution YO_x-rich particles” effectively suppresses the grain growth of W and leads to the formation of nanocrystalline W-10Cr-5Y alloy. W-10Cr-5Y has an ultra-high hardness, with a Vickers hardness of 1312 ± 12 kgf·mm⁻². High-temperature annealing treatment shows that W-10Cr-5Y has good thermal stability at 1000 and 1100 °C, as demonstrated by the comparison of Vickers hardness and grain size between annealed and unannealed alloys.