Effect of nanoparticle fraction on Portevin-Le Chatelier effect of ZrB2 nanoparticle-reinforced AA6xxx composites

In this paper, the influence of nanoparticle fraction on Portevin-Le Chatelier effect of ZrB2 nanoparticle reinforced AA6xxx composites was investigated and friction stir processing was used to uniformize the distribution of nanoparticles. The results indicated that the population of serrations decreases with increasing the fraction of ZrB2 particles, with stress-drop serrations dominate the early stages of deformation while the stress-up serrations increase with the strain. The stress distribution complies with bimodal configuration, and 2 peaks become closing with the increasing fraction of nanoparticles. The interval for unconstrained motion of dislocation is responsible for the suppression of Portevin-Le Chatelier effect. The mean interval decreases with increasing the nanoparticles fraction. The inter-twisted dislocations in small intervals continuously dedicate to instant balance of stress-drop serrations, strengthen composites and favor the plastic deformation.

Automated summary

The study found that as the fraction of ZrB2 nanoparticles increases, the number of deformation serrations decreases, leading to a shorter interval for constrained dislocation motion and the suppression of the Portevin-Le Chatelier effect.