An infinite face-centered cubic single crystal containing an isolated cylindrical μm-sized void, which was subjected to proportional and monotonically uniform equal biaxial tension loading, was adopted to study the scale-dependent void growth and its intrinsic mechanism by employing a two-dimensional planar discrete dislocation dynamic framework. First, a typical dislocation distribution near the micro-voids was presented and the void growth mechanism was revealed by dislocation shear loop expansion for each of three typical face-centered cubic slip systems. The effect of size on void growth was then investigated. The general conclusion that voids at the micron or sub-micron scale were less susceptible to growth than larger ones was drawn. Another result, which could not be deduced from the continuum theories, was also achieved: at the micron or sub-micron scale, larger voids grew smoothly with remote strain, while smaller voids usually grew in a so-called leapfrog manner. Specifically, when the void was even smaller, it grew in an approximately linear-elastic manner since only few dislocations were present around the void. Further analyses indicated that these size effects were closely related to the dislocation density on the void surface and the dislocation mobility around the void. Finally, the influences of the dislocation sources/obstacles density and their random distribution in materials on the void growth were studied briefly. Results showed that there exists remarkable scatter in the micro-void growth due to random distribution of the dislocation sources or obstacles, especially for voids at the sub-micron scale.

Discrete Dislocation Dynamics Modelling of Microvoid Growth and Its Intrinsic Mechanism in Single Crystals. M.Huang, Z.Li, C.Wang: Acta Materialia, 2007, 55[4], 1387-96