The effects of atomic-scale voids on the strength and mechanical behavior of aluminum at zero temperature are investigated using the total-energy pseudopotential method. A series of calculations are performed in which the defective system is extended by a small increment and then is relaxed to its ground state configuration. The total energy and stress are determined at each level of strain. The ‘‘tensile test’’ of the defective system is compared with the results of an experiment on a perfect system. These simulations employ a quantum mechanical scheme and show the processes of deformation around the defects including the initiation of dislocations and slip. They can also be used as a database on which to test models based on simpler atomistic potentials. We use them in that way to test a Sutton-Chen model tuned to our quantum mechanically simulated system, and a pairwise model by way of contrast to metallic bonding. The Sutton-Chen model shows significant void expansion at about 60% of the failure strain, an effect which is not seen in the ab initio calculations. The ab initio calculations suggest how empirical models such as the Sutton-Chen scheme can probably be improved to reflect better the nature of metallic bonding.

• Received 11 July 1995

DOI:https://doi.org/10.1103/PhysRevB.52.15191