DUCTILE FRACTURE BY VACANCY CONDENSATION IN FCC SINGLE-CRYSTALS

We explore the feasibility of vacancy condensation as the void-nucleat ing mechanism underlying ductile fracture by void growth and coalescen ce in single crystals at room temperature. Vacancies are presumed to b e primarily generated by the dragging of intersection jogs. The equati ons governing the rate of growth of voids by vacancy condensation are derived. These equations are used to follow the evolution of vacancy c oncentrations and void sizes in the Wang and Anderson [Acta metall. 39 , 779 (1991)] [1] Sigma 9 test. We find that, when pipe diffusions are taken into account, the time required for the nucleation of a macrosc opic void in the near-tip region is of the order of one minute, which is well within the lime-scale of quasistatic fracture tests.