At elevated temperatures, crystal dislocations impinging onto the grain boundary become trapped and are confined to move in the interface. They form pile-ups at places where their movements are impeded in the interface the strength of which is determined by the rate of slip impingement and that of recovery in the interface. During steady state creep, a ‘steady state’ pile-up of grain boundary dislocations (GBDs) will form in the interface, providing a condition conducive to the formation of creep cavities. Calculations have shown that cavity nucleation ahead of a GBD pile-up during steady state creep is feasible under usual creep conditions in single-phase metals and alloys. It has also shown that solutes and impurities can exert a profound influence on the cavitation behavior of materials. For a solute/impurity which is surface active, which retards boundary diffusion and reduces the creep resistance of the material, it could reduce the threshold stress for cavitation failure by about an order of magnitude, thereby rendering the material highly susceptible to cavitation damage.