Abstract
Al-doped U3Si2 composite fuels with controlled microstructure were fabricated by spark plasma sintering that display greatly-improved oxidation resistance as compared with monolithic and Al-doped silicides prepared by standard powder metallurgy or arc melting. The effects of Al additives on the thermal-mechanical properties and oxidation resisance of the micron- and nano-sized U3Si2 composites were investigated. A minimal addition of 1.8 at% Al is effective to increase the onset oxidation temperature of as-fabricated U3Si2 pellets to 580 °C, which can be further increased to 610 °C by thermal annealing. The Al-doped U3Si2 composite fuels also display simultaneously higher hardness and fracture toughness than un-doped U3Si2. These results highlight an effective strategy by integrating minimal Al additives, microstructure control and post-thermal annealing to design advanced silicide fuels with excellent oxidation resistance, desired thermal-mechanical properties and maintained high fissile element density.
