The Mechanism of Cavitation in Copper during Creep

Abstract

During creep of copper, cavities form on grain boundaries and cause a decrease in density. The fractional change in density during creep is proportional to (time)^1.5, in reasonable agreement with previous work. Cavities are nucleated continuously during creep, the number present being proportional to (time)^0.5. The results suggest that an individual cavity increases its volume at a constant rate in keeping with a growth mechanism that involves diffusion of vacancies along the grain boundary to the cavity surface. When tensile creep specimens are compressed slowly at 400° C or at room temperature the density increases by similar amounts, suggesting that sintering does not occur by reversed grain-boundary sliding. The cavities formed by creep become stabilized by the diffusion of gas into them.