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Radiation damage in metals at elevated temperatures produces small dislocation loops and voids. The growth of these sinks is determined by the steady−state diffusion of point defects migrating in the stress field of these sinks. To obtain the steady−state current of point defects to these spherical sinks a perturbation method is developed to deal with the drift term of the diffusion equation. It is shown that the contribution of the drift term to the current can be expressed by a bias factor which differs from unity if the point defects interact with the spherical sink. Explicit expressions of the bias factors for voids and infinitesimal dislocation loops are given. If the metal is subject to external loads the bias factors of voids depend on the elastic dilatation, whereas the bias factors for dislocation loops depend on the deviatoric elastic strain. These results then provide the basis for stress−induced swelling and irradiation creep of metals. Both of these phenomena are briefly discussed.

Flux distributions are determined numerically for quasistatic conditions within the Bean model. The field penetration ranges from 0 to 100%. The moving boundary of this distribution is calculated using an optimization technique to force the field component on the boundary to vanish, the variables being the parameters describing the boundary curve. The hysteresis loss is found using the flux distribution for a variable field superposed on a constant bias; the two fields are parallel to each other and transverse to the wire axis.

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The steady-state diffusion of radiation-produced point defects in the stress field of an edge dislocation is solved by a perturbation method. The drift term entering the diffusion equation includes the size interaction and the inhomogeneity interaction as well as the effects of externally applied loads. By comparing the perturbation solution with the rigorous solution of Ham, we show that the perturbation solution is always adequate provided the drift term is proportional to the gradient of the interaction energy of the point defect with the dislocation. The steady-state distributions of vacancies and interstitials is such that voids or vacancy clusters preferentially grow on the compressive side of the edge dislocation. The external stresses give rise to an orientation-dependent bias of the edge dislocation which is shown to provide a possible mechanism for radiation-induced creep.

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