Effect of Y₂O₃ nanoparticles on enhancing microstructure and mechanical properties of oxide dispersion strengthened W alloy

Dispersion of oxide nanoparticles in W, leading to the dispersion strengthening of W alloys, has emerged as a viable strategy to overcome the brittleness of W. In particular, the introduction of stable Y₂O₃ as a secondary phase refines the grain and enhances the densification of W, leading to an increase in the density of sintered alloy. Thus, analyzing the composite effects of Y₂O₃ on the alloy, which has homogeneous dispersion of Y₂O₃ nanoparticles, can allow enhanced mechanical properties of the W-Y₂O₃ alloy. However, to date, most studies have focused on synthesis methodology for nanocomposites, which is advantageous to grain refinement and dispersion. It is worth paying attention to the interaction in the W-Y₂O₃ system, such as the ternary oxide system (W-Y-O) with a low eutectic temperature and the possibility of liquid-phase sintering, which has been reported a few. In this study, the effect of Y₂O₃ nanoparticles on the microstructure and micro-Vickers hardness of W was experimentally evaluated. W-Y₂O₃ alloys with precisely controlled compositions from 1 wt% to 10 wt%Y₂O₃ were successfully fabricated using an ultrasonic spray pyrolysis process and a subsequent spark plasma sintering. The proposed process yielded Y₂O₃ nanoparticles with uniform dimensions and distributions even after sintering. Furthermore, the formation of Y₂WO₆ and a liquid-phase sintered structure, as products of the interaction between W and Y₂O₃ depending on the Y₂O₃ fraction, were observed, and thermodynamical formation routes were suggested. Evidently, the W-2wt%Y₂O₃ sintered alloy, with uniformly dispersed Y₂O₃ nanoparticles (<50 nm), exhibited an improved hardness of 7.21 ± 0.15 GPa, as the W grains were refined to approximately 760 nm, and their density increased to 96.48%.