Are There Limitations to the Hall-Petch Relationship?
Yes, there are limitations. As the grain size continues to decrease to the nanometer range, the Hall-Petch relationship may break down. This is due to the transition from dislocation-mediated plasticity to other deformation mechanisms such as grain boundary sliding or diffusion creep. In extremely fine-grained materials, a phenomenon known as inverse Hall-Petch effect may occur, where further reduction in grain size leads to a decrease in strength.
