Fabrication of Mo-Y2O3 alloys using hydrothermal synthesis and spark plasma sintering.

Fine-grained Mo alloys doped with uniformly distributed nanoscale Y 2 O 3 particles were successfully prepared by employing two powerful strategies: fabricating high-quality precursor powders using hydrothermal synthesis and subsequent powder consolidation by spark plasma sintering (SPS) technique. In this study, the effect of hydrothermal variables on the morphology and existent form of yttrium and Mo was systematically studied, and the refinement mechanism of reduced mixing powders and the densification under the different sintering parameters were investigated. The results show that spherical Y 2 (CO 3) 3 ·2H 2 O gradually replaced Y(OH)CO 3 owing to the increased concentration of hydrogen bonds and CO 3 2− at excess alcohol and urea, and lamellar (NH 4) 2 Mo 4 O 13 developed into large pillar-shaped h-MoO 3 with decreasing pH. Due to the low calculated lattice mismatch degree of Mo/Y 2 O 3 interfaces ~10.9%, Y 2 O 3 particles further refined and homogenized the reduced mixing powders as heterogeneous nucleating sites. After sintering at 1700 °C for 5 min with a heating rate of 100 °C/min, Mo-Y 2 O 3 alloys possessed fine grains of 1.80 ± 0.17 μm, a high density of 98.18% and the high indentation hardness of 314.77 ± 26.12 HV 0.3 and 4.82 ± 0.53 GPa H IT. The Y 2 O 3 particles were uniformly distributed in the Mo matrix, and semi-coherent with Mo lattice, with the orientation relationships as follows: (010) Y2O3 //(011) Mo , (01-1) Y2O3 //(020) Mo , and [100] Y2O3 //[100] Mo. • Fine-grained Mo alloys doped with nanoscale Y 2 O 3 particles were fabricated by using hydrothermal synthesis and SPS technique. • Y 2 O 3 particles refined and homogenized the reduced mixing powders by acting as heterogeneous nucleation sites. • The Y 2 O 3 particles were uniformly distributed in the Mo matrix, and semi-coherent with Mo lattice. [ABSTRACT FROM AUTHOR]