TRUNCATED DISLOCATION SOURCES IN NANOMETRIC ALUMINUM CRYSTALS: A MOLECULAR DYNAMICS STUDY

In this study, the evolution of dislocation loops truncated by free surfaces in small finite volumes is investigated in aluminum using molecular dynamics simulations. Three types of truncated dislocation loops, U-shaped, C-shaped and L-shaped, are considered. In the absence of truncated dislocation loops and without applied stress, surface effects induce the formation of very large stress gradients, of the order of several GPa's. Under an applied shear strain, the evolution of the truncated loops reveals the occurrence of several major phenomena. Very large stacking faults were formed during motion of the partial dislocations and the development of full and helix dislocations were observed. In addition, cross-slip behavior by the Fleischer mechanism, twin formation and untwinning were identified.