Core-structure and lattice friction of twinning dislocation in platinum

SSR Pulagam and S Kumari and A Dutta, MATERIALS TODAY-PROCEEDINGS, 44, 2968-2971 (2021).

DOI: 10.1016/j.matpr.2021.02.121

Only the coarse-grained fcc metals with low stacking fault energies have a high propensity to deformation twinning; however, nanocrystalline metals with high SFEs may also show deformation twinning with different twinning nucleation paths. Contrary to the convectional twinning routes, a new alternate-shear mechanism for nucleation of twins in nanocrystalline platinum has recently been proposed, though very little information is available regarding the fundamental parameters of the twinning dislocations involved there. In the present study, we examine the core-structure and lattice resistance of these twinning dislocations by employing an integrated approach of atomistic simulations and the variational Peierls Nabarro model. Exploring the core-width and the Peierls stresses of the twinning dislocations is critical in connecting the atomistic scale model to the mesoscale model. Here, we employ the fully anisotropic elasticity formalism and a robust optimization protocol to solve the variational problem. A two-dimensional generalized planar fault energy with negative SFE is obtained in this scheme, and the near-field elastic displacement is estimated. (C) 2021 Elsevier Ltd. All rights reserved.

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