Thermal Expansion and Elastic Properties of Th–6U–4Zr Alloy

The Th–6wt%U–4wt%Zr alloy—a prospective thorium based metallic fuel for fast reactor applications, has been studied for its microstructural, thermal and elastic properties. The X-ray diffractometer of the alloy annealed at 1423 K and quenched showed α -thorium peaks and shrinkage in lattice parameter as compared to thorium. The scanning electron microscope attached to energy dispersive spectroscope revealed uranium rich precipitates dispersed in α -thorium matrix. The Coefficient of thermal expansion (CTE) of the alloy showed a change in slope at 939 K which corresponds to onset of α -U ⇋ β -U phase transformation along with α -thorium phase. The CTE of the alloy was 12.2 × 10 –6 /K at 1000 K which is comparatively less than uranium alloys fuels. Vickers hardness and elastic properties measurement showed an increase in strength of the alloy due to solid solution strengthening as compared to thorium.