Aluminum Alloy AA7075 has a high volume fraction of Al-Cu-Fe constituent particles (1.5%-2.5%). Under fatigue loading these particles will crack and nucleate fatigue cracks into the surrounding aluminum matrix. For a given region of interest many (tens to hundreds) of micro-cracks may propagate simultaneously. These micro-cracks will interact through shielding and or coalescence, which can result in discontinuous growth rates and contribute to variability in component lifetime predictions. Digital microstructure reconstructions of the alloy are utilized to simulate the process of micro-crack growth and coalescence. The synthetic digital microstructures are matched to experimental measurements of distributions of grain size, shape and particle characteristics (especially spatial correlation).  In the digital microstructure a 3D volume of grains (with assigned crystallographic orientations) and constituent particles are generated and then subsequently sliced. The resulting 2D field of particles embedded in a polycrystalline matrix is allowed to nucleate fatigue cracks. Linkup events and crack size statistics are tracked as a function of cyclic loading.