The theory of blister formation

Abstract

Abstract The generation of blisters due to irradiation by helium ions is investigated theoretically. The possible pressure in helium bubbles in metals, the binding energy of helium atoms and vacancies to a bubble are calculated. The kinetics of bubble growth is studied. Using the known profiles of implanted ions and defects, the gas pressure in bubbles and the stress in a layer are computed as a function of the layer depth, x. Supposing that a crack is formed, at a depth of maximum stress, at the moment, when the stress reaches the point of fracture, expressions for the depth of crack generation and of the critical dose of blister formation are obtained. They are in good agreement with experiment. Estimations of the gas quantity discharged in the crack and of integral lateral stress in an irradiated layer are given. On the basis of these estimations, a conclusion is made of a possibility of blister buckling as being due to pressure inside the blister, on account of the inner stresses in the blister cover....