Synthesis of W-Y2O3 alloys by freeze-drying and subsequent low temperature sintering: Microstructure refinement and second phase particles regulation

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2020,（1）
• 页码范围: 84-90
• 页数: 7页
• 语种: 英文

摘要

In this work,W-Y2O3 alloys are prepared by freeze-drying and subsequent low temperature sintering.The average size of reduced W-Y2O3 composite powders prepared by freeze-drying method is only 18.1 nm.After low temperature sintering of these composite nanopowders,the formed W-Y2O3 alloys possess a smaller grain size of 510 nm while maintaining a comparatively higher density of 97.8％.Besides a few submicron Y2O3 particles (about 100-300 nm) with a W-Y-O phase diffusion layer on their surface distribute at W grain boundaries,lots of nano Y2WO6 particles (＜20 nm) exist in W matrix.Moreover,many Y6WO12 (＜10 nm) particles exist within submicron Y2O3 particles.The formation of these ternary phases indicates that some oxygen impurities in the W matrix can be adsorbed by ternary phases,resulting in the purification of W matrix and the strengthening of phase boundaries.The combined action of the above factors makes the hardness of the sintered W-Y2O3 alloys in our work as high as 656.6±39.0 HV0.2.Our work indicates that freeze-drying and subsequent low temperature sintering is a promising method for preparing high performance W-Y2O3 alloys.