Mechanical properties of (U,Ce)O 2

Abstract

Ultrasonic pulse echo and Vickers hardness measurements were performed to estimate the mechanical properties of single crystal UO 2 and sintered (U,Ce)O 2 with various porosities. From the sound velocities obtained for single crystal UO 2 and sintered (U,Ce)O 2, the Young's and shear moduli and Poisson's ratio were estimated. The Young's and shear moduli and Poisson's ratio decreased with the CeO 2 content. By careful measurements with various loads, the Vickers hardness of 100% dense (U,Ce)O 2 (porosity 0%) was obtained. The value for 100% dense UO 2 was in good agreement with the hardness of single crystal UO 2. The Vickers hardness of (U,Ce)O 2 also decreased with the CeO 2 content, irrespective of porosity (0 and 14% porosity). There is a good correlation between the Young's modulus and the Vickers hardness obtained for (U,Ce)O 2 irrespective of porosity. The yield stress of (U,Ce)O 2 evaluated from both the Young's modulus and the Vickers hardness decreased with the CeO 2 content. The diagonal of the radial crack of UO 2 single crystal was also measured, and the fracture toughness K C was estimated to be 1.1±0.2 MPa m 1/2.