A novel dissolution-precipitation strategy to accelerate the sintering of yttrium oxide dispersion strengthened tungsten alloy with well-regulated structure

Abstract

In this work, accelerated sintering of Y2O3 dispersion strengthened tungsten alloy with a well-regulated structure was achieved by a novel dissolution-precipitation strategy. As indicated, yttrium oxide was firstly dissolved into the lattices of W powder precursor during the thermal plasma synthesis process in a one-step and ultra-fast way, and then homogeneously precipitated out within W grains during sintering. The theoretical calculation reveals that the formation process of Y2O3 dispersoids enhanced the driving force of densification by increasing the sintering stress and declining the macroscopic viscosity, resulting in improved diffusion ability for the W skeleton. The microstructural investigation further confirmed the occurrence of mass inter-diffusion at the W-Y2O3 interface, which provides a fast diffusion pathway for W atoms, and is responsible for the accelerated densification kinetics. Being sintered at 1600 °C for 1 h, the as-obtained alloy possesses a high relative density of 98.26%, together with a refined grain size of 970 nm for W and 50 nm for intragranular Y2O3, respectively.