  We clarify via molecular dynamic simulations and theoretical analysis the
origin of dislocation creation and void nucleation during uniaxial tensile
process in face-centered-cubic (FCC) ductile metals. We show that the
dislocations are created through three distinguished stages: (i) Flattened
octahedral structures (FOSs) are randomly activated by thermal fluctuations;
(ii) The double-layer defect clusters are formed by self-organized stacking of
FOSs on the close-packed plane; (iii) The stacking faults surrounded by the
Shockley partial dislocations are created from the double-layer defect cluster
due to the relative slip of internal atoms. Whereas, the void nucleation is
shown to follow a two-stages description: (i) The vacancy strings are first
formed by intersection of different stacking faults; (ii) Then the vacancy
strings transform into the voids by emitting dislocations. We demonstrate that
our findings on the origin of dislocation creation and void nucleation is
universal for a variety of FCC ductile metals with low stacking fault energy.
