The effects of sintering temperature on the microstructural evolution and mechanical properties of yttrium hydride monoliths via spark plasma sintering

Abstract

In recent years, yttrium hydride has garnered significant attention due to its remarkable thermal stability and potential for high hydrogen density. It is regarded as one of the most promising metal hydrides for use as a neutron moderator in microreactors. In this study, yttrium hydride monoliths were synthesized using yttrium hydride powder obtained through direct hydrogenation, facilitated by Spark Plasma Sintering (SPS) at temperatures ranging from 800 to 1200 ℃. The effects of SPS temperatures on the phase composition, microstructure, density, and mechanical properties of yttrium hydride monoliths were studied. The results show that the sintering temperature markedly impacts the hardness, pore evolution, grain size and precipitation of α-Y and Y2O3 phase. Notably, the hardness of the samples escalates significantly with an increase in sintering temperature below 1000 ℃, influenced by a reduction in both the number and size of pores. The occurrence of twin crystals, distribution of grain size and the phase-transformed particles of α-Y within the sintered sample may contribute to an increase in hardness. The procedures described herein affect developing important microstructure-property relationships, as well as correlations in the sintering parameters and mechanical properties.