RADIATION EFFECTS ON ELASTICITY OF METALS

For a metal containing a periodically arranged (three-dimensional) system of voids, explicit analytical expressions are developed for the bulk and the shear moduli (and, consequently, Young's modulus and the Poisson ratio), on the assumption that the metal is initially (nonirradiated) homogeneous and isotropic. These expressions include the effect of the interaction between adjecent voids and the void size, but do not take into account the effects of the void shape. The results are compared with previous estimates by other investigators who did not include the influence of the interaction between adjacent voids. The interaction effect becomes more pronounced with the increasing volume fraction of the voids. Hence, the present results provide more realistic estimates of the material elasticity. These and related results are illustrated by means of numerical examples. Then the mechanism of void and gas bubble formation in irradiated metals is briefly discussed and some relevant theoretical and experimental results are summarized. In particular, curves are developed which relate the reduction in elastic moduli to the neutron fluence, temperature, and other relevant parameters. Finally, on the basis of an approximate model we give a rough estimate for the reduction in the yield stress due to irradiation. © 1979.