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Abstract

The Hertzian indentation technique has previously been used to measure fracture surface energies, gamma-f, and fracture toughness, K-Ic, for a number of fuel materials including ThO-2, UO-2, (U, Pu)O-2, as well as advanced fuels (U,Pu)(C,N). A very suitable material to develop the potential of the technique is ThO-2 since it the cracks formed are easy to find and to measure and a good correlation exists between crack formation and acoustic emision, as a second independent means to observe crack formation. ThO-2 was thus used to measure the depth of Hertzian cracks experimentally and to study the effect of sample temperature on gamma-f and K-Ic. In the present communication, the effect of irradiation with doubly charged (He++)-ions (alpha particles) is reported. Hardly any quantitative information is available on the fracture properties of irradiated nuclear fuels. The Hertzian technique is ideally suited to study the effect of irradiation on fracture toughness and fracture surface energy because the small sizes of irradiation on fracture toughness and fracture surface energy because the small sizes of irradiated samples are sufficient and can efectively be used for parametric studies. In the Hertzian indentation technique, a spherical indentor with radius R is pushed into the surface of the specimen until, at a critical load, P-c, a ring crack forms (radius r). The experimental details and the mathematics to deduce gamma-f and K-Ic have been given in detail before. In brief the fracture toughness K-Ic is calculated from the relation where the crack extension function a/c[phi]**-2 depend on the size of the crack and can be obtained from numerical integration provided by Warren, a beta is a numerical constant (=8pi**3/27), k is a measure of the elastic mismatch between indentor and specimen (here k=1.03), and E is elasticity modulus indentor and specimen (here k=1.03), and E is elasticity modulus (here 210 GPa).

Additional information

Authors: MATZKE HJ JRC KARLSRUHE ESTAB. (GERMANY) ROUTBORT J L ARGONNE NATIONAL LABORATORY (USA) , JRC KARLSRUHE ESTAB. (GERMANY);ARGONNE NATIONAL LABORATORY (USA)
Bibliographic Reference: JOURNAL OF NUCLEAR MATERIALS, VOL. 115 (1983), PP. 334-336
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