Inverse Hall-Petch Behavior in Nanocrystalline Aluminum Using Molecular Dynamics

This work investigates the mechanical behavior of nanocrystalline aluminum, with special focus on deformation mechanisms, using molecular dynamics simulations with an interatomic potential parameterized by the authors. To this end, four nanocrystalline samples with grain sizes ranging from 8,2 to 14,2 nm were constructed, each with a volume of 15 x 15 x 20 nm(3). As expected, the data from the tensile tests at a strain rate of 1,0 x 10(9) s(-1) showed an inverse Hall-Petch relationship. The work hardening behavior revealed no significant gain in mechanical strength. The dislocation analysis indicated that perfect dislocation density decreases during tensile testing, while the Shockley partials increase. Grain boundary-mediated plasticity was evidenced with atomic diffusion along grain boundaries, as well as by grain rotation. Thus, it is concluded that the conventional plastic deformation mechanisms of metals are not preponderant for nanocrystalline aluminum.

Automated summary

This study investigates the mechanical behavior of nanocrystalline aluminum, focusing on deformation mechanisms using molecular dynamics simulations. Four nanocrystalline samples with varying grain sizes were created and subjected to tensile tests. The results showed an inverse Hall-Petch relationship and negligible improvement in mechanical strength. Dislocation analysis revealed a decrease in perfect dislocation density and an increase in Shockley partials during testing. Grain boundary-mediated plasticity was observed through atomic diffusion and grain rotation. This suggests that conventional plastic deformation mechanisms are not dominant in nanocrystalline aluminum.