THE PRESSURE FOR DISLOCATION LOOP PUNCHING BY A SINGLE BUBBLE

A detailed analysis is given on the energetics of bubble growth in a solid by primatic loop punching. Interactions between the bubble and the dislocation loop are included as well as the effect of the loop proximity on the actual bubble volume. It is shown that there exists an attraction between bubble and loop and that the bubble volume increases gradually as the loop recedes from the bubble. As a result, there exists an energy barrier for loop punching which requires a significantly higher pressure than previously assumed. Futhermore, the critical pressure for loop punching reaches a nearly constant value with increasing bubble radius. The calculations are carried out for the case of nickel at room temperature, and it is predicted that helium within the bubbles is in the solid state.