Deformation processes in polycrystalline Zr by molecular dynamics simulations

Abstract

a b s t r a c tMolecular dynamics simulation is used to characterize the deformation behavior of polycrystalline Zr. The predictions of two different potentials, an embedded atom method potential and a charge optimized many body potential are compared. The experimentally observed prismatic dislocations, pyramidal dislocations and twinning behaviors are produced in the simulations of ½1 1 2 0 and [0 0 0 1] textured structures and in fully 3D structure simulations. The relationship between the generalized stacking fault energy and the mechanical properties is discussed. In particular we find that the different shapes of the generalized stacking-fault energy curve for the two different interatomic descriptions of Zr have a significant effect on the deformation mechanisms. The deformation behavior of Zr is compared with analogous simulations of deformation of polycrystalline Mg.

Nanoindentation of Zr by molecular dynamics simulation

“…As is well known, the stacking fault and unstable stacking fault energies play an important role in determining the dislocation behaviors [18]. A comparison of the stacking fault energies of MA EAM potential and COMB potential was reported previously [20]. Summarizing these previously reported results, the stable and unstable stacking fault energies along the basal partial <a> path for the COMB potential are higher than for the MA EAM potential, while the most reliable DFT values are the lowest.…”

“…Comparing to the DFT results, both potentials also predict relatively accurate unstable and stable stacking fault energy. Most importantly, for both potentials the energy barrier for basal slip is higher than that of prismatic slip, ensuring that the potentials predict the prismatic slip to be the dominant slip mode [20].…”

“…Molecular dynamics (MD) simulation has been used as an effective tool to study the deformation process of metals [15][16][17][18][19][20] at the atomic level. For example, Van Swygenhoven and coworkers have shown that the stable and unstable stacking fault energies have a strong influence on deformation behavior in fcc metals [18].…”

“…For example, Van Swygenhoven and coworkers have shown that the stable and unstable stacking fault energies have a strong influence on deformation behavior in fcc metals [18]. Work on Zr by Lu using polycrystalline models discussed the relationship between deformation behaviors and the stable and unstable stacking fault energies [20]. The nanoindentation process has been studied using molecular dynamics in fcc [21][22][23][24], bcc [25,26] and hcp [27] metals.…”

Atomic-scale modeling of twinning disconnections in zirconium

“…This potential, developed for bulk hcp Zr with a special emphasis on stacking faults controlling dislocation dissociation, has already been shown to give a reliable description of Zr plasticity. [22][23][24][25][26][27][28] Ab initio calculations were performed with the VASP code, 29 using the Perdew-Becke-Erzenhof 30 parameterization for the GGA exchange and correlation functional. The interactions between the core and outer electrons are modeled through the projector augmented wave approximation, considering valence (5s 2 4d 2 ) and semicore electrons (4s 2 4p 6 ) in the outer shell.…”