Spark Plasma Sintering of fine-grained ceramic-metal composites YAG:Nd-(W,Mo) based on garnet-type oxide Y2.5Nd0.5Al5O12 for inert matrix fuel

Powders of garnet-type complex oxide Y2.5Nd0.5Al5O12 (YAG:Nd) - x vol% W, Mo (x = 0, 10, 20) were obtained using wet chemistry techniques and precipitation of the metal phase from salt solutions. After synthesis, nanoparticles of YAG:Nd garnet cluster into submicron agglomerates. Spark Plasma Sintering (SPS) was used to obtain fine-grain ceramic-metal composites YAG:Nd - (W, Mo) with a relative density of ∼99%. The effect that metal concentration (tungsten, molybdenum) has on density, microstructure properties, and mechanical properties (microhardness, fracture toughness) of ceramics was studied. SPS activation energies were determined and it was demonstrated that the intensity of shrinkage of the fine-grained YAG:Nd - (W,Mo) ceramic-metal composites close to the activation energy of creep in tungsten (molybdenum). It has been demonstrated that the intensity of creep during SPS of fine-grained composites at medium temperatures is determined by the intensity of volume oxygen diffusion in the lattice of garnet nanoparticles, whereas at high temperatures it is determined by grain-boundary diffusion.