Defect cluster configurations and mobilities in α-Zr: A comparison of the BMD19 and M07 interatomic potentials

Abstract

Preferred defect cluster configurations and diffusion behavior are calculated with the recently published BMD19 interatomic potential for α-zirconium and compared with results calculated from the M07 potentials. Both potentials predict that small SIA clusters form configurations contained entirely within a single basal plane, while large SIA clusters form perfect dislocation loops on first-order prismatic planes with Burgers vector b→=13<112¯0>. The M07 potentials predict stable void formation for vacancy clusters while the BMD19 potential accurately indicates a preference for planar configurations on either first-order or second-order prismatic planes. Small basal vacancy clusters are found to form faulted pyramidal structures and only transform to faulted c-loops at larger sizes. In evaluating the defect diffusivity, single vacancies and interstitials are both found to exhibit anisotropic diffusion within the basal-plane. Small SIA clusters are found to migrate exclusively in 2-D within a single basal plane with the BMD19 potential but migrate in 3-D with the M07 #3 potential. Small vacancy clusters are either unstable or immobile with the M07 #3 and #2 potentials, while these clusters exhibit appreciable mobility either along the c-axis or in a quasi-isotropic manner with the BMD19 potential. The apparent difference in the diffusional anisotropies of defect clusters, rather than point defects, could be a critical component for improving predictive capabilities for mesoscale modeling of microstructural evolution in α-zirconium.