Integrated first-principles calculations and crystal plasticity finite element simulations for nickel single crystal deformation

Tuesday, September 14, 2021: 8:40 AM
225 (America's Center)
Prof. Allison Beese , Pennsylvania State University, University Pk, PA
Prof. Zi-Kui Liu , Pennsylvania State University, University Pk, PA
Mr. Shipin Qin , Pennsylvania State University, University Pk, PA
Dr. Shun-Li Shang , Pennsylvania State University, University Pk, PA
Mr. John Shimanek , Pennsylvania State University, University Pk, PA
While the crystal plasticity finite element method (CPFEM) can be used to capture the deformation behavior of single crystals, often the parameters for the material models in this method are calibrated from macroscopic experiments, with unclear direct physical explanations for all parameters. This presentation will discuss recent work in which we propose a multiscale approach consisting of using density functional theory (DFT)-based first-principles calculations of pure Ni deformation to determine CPFEM parameters, where CPFEM simulations are then used to predict the strain hardening behavior of pure Ni single crystal. DFT-based calculations were used to compute the ideal shear stress and elastic constants of pure Ni as a function of an applied deformation used to represent stress/strain fields associated with dislocation motion. From these values, the Peierls stresses for pure edge and pure screw dislocations as a function of applied deformation were computed. We propose a slip system level constitutive law for CPFEM that describes the strain hardening behavior of a slip system as solely having contributions from edge dislocations at small strains, with screw dislocations contributing to the flow stress with applied deformation. This mimics the evolution of purely edge dislocations at small strains to interactions of edge dislocations resulting in screw components with large strain. This framework is able to capture the experimentally reported deformation behavior of pure single crystal Ni up to large deformations.