Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find 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 are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

Stretchable and conductive fibers are ideal for wearable intelligent electronics, especially wearable strain sensors. However, two main challenges strictly restrict the advancement of wearable strain sensors: the contradictory between sensitivity...

Emergence and time evolution of micro-structured new-phase domains play a crucial role in determining the macroscopic physical and mechanical behaviors of iron under shock compression. Here, we investigate, through molecular dynamics simulations and theoretical modelings, shock-induced phase transition process of iron from body-centered-cubic (bcc) to hexagonal-close-packed (hcp) structure. We present a central-moment method and a rolling-ball algorithm to calculate and analyze the morphology and growth speed of the hcp phase domains, and then propose a phase transition model to clarify our derived growth law of the phase domains. We also demonstrate that the new-phase evolution process undergoes three distinguished stages with different time scales of the hcp phase fraction in the system.

The interface evolution characteristics and deformation mechanisms of Cu/Al multilayers are investigated via systematic molecular dynamics simulations. It is found that both the yield strength and ductility increase slightly with increasing strain rate, and the stress-strain curves exhibit two main yield points for all strain rate loadings. The first yield point correlates with the decomposition of perfect misfit dislocations on the interface and the propagation of partial dislocations inside the Al layer, and the second yield point relates with the dislocation transmission from the Al layer into the Cu layer. The lower the loading strain rate, the more severe the fluctuations on the stress-strain curve. However, the strain rates do not change the evolution way of dislocation networks. The calculated evolution curves of dislocation numbers indicate that the dislocation density inside the Cu layer is lower than that inside the Al layer. The interface region displays a serrated structure without voids or cracks, and the higher the loading strain rate, the more serious the interface roughening deformation. The main deformation mechanisms, respectively, are the formation of a lamellar twin structure in the Cu layer and dislocation slip in the Al layer, and the interface roughening is mainly dominated by the formation of a lamellar twin structure. Furthermore, the deformation mechanisms do not depend on the strain rate applied in this paper. In addition, we also discuss the growth curve of interface thickness which is divided into three stages.