Effects of sintering temperatures on the thermal conductivity and microstructural evolution of yttrium hydride monoliths by spark plasma sintering

In this study, YHx (where x represents the H/Y ratio) monoliths were fabricated using Spark Plasma Sintering (SPS), employing yttrium hydride powder as the raw material. The effects of different sintering temperatures (800 °C–1200 °C) on the thermal conductivity and microstructural evolution of the YHx monoliths, including porosity, grain size, precipitated phases, and internal defects, were investigated. The results indicate that the sintering temperature exerts a significant influence on thermal conductivity and microstructural evolution. Notably, the thermal conductivity of these samples initially increases with rising sintering temperature, but subsequently decreases under identical testing conditions. This phenomenon is primarily attributed to the effects of porosity and precipitate phase. Furthermore, the presence of twin crystals also contributes to the reduction in thermal conductivity. The procedures provide an initial framework for understanding the relationship between thermal conductivity and the evolution of microstructure.