On the origin and universality of dislocation creation and void nucleation in FCC ductile metals

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.

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