Deformation mechanism in the mechanical response of nano polycrystalline HCP Zr and Zr-2.5 Nb: An atomistic study

Deformation-induced dislocations in polycrystalline hexagonal close-packed (HCP) metals have a great influence on the mechanical properties of materials. We use atomistic simulations to study the deformation behavior of Zr and Zr-2.5 Nb. We investigate the effects of grain orientation and loading directions on the nucleation and interactions of dislocations. We find that different deformation modes are activated under different loading directions, which may explain experimentally-observed superior mechanical strength under transverse loading than under radial loading. In addition, our simulations show that alloying leads to a more deformation-resistant material, due to the segregation of solute atoms to grain boundaries (GBs) as well as dislocation pinning, which makes emission from GBs more difficult. This study lays the foundation for investigating deformation through atomistic structural analysis.