The mesh method: accurate determination of two-dimensional energy landscape of dislocation motion in bcc metals and alloys
Date:
2023 Materials Research Socienty Spring Meeting & Exhibition
Abstract
The unusual low-temperature plasticity behaviors of bcc metals and alloys are known to be attributed to the complex core structure of screw dislocations, whose motion is governed by thermally activated kink-pair nucleation mechanisms on the two-dimensional Peierls potential. However, this 2D energy surface is usually estimated by simplified elasticity theory in pure bcc metals, with limited applicability to complex bcc systems such as bcc high-entropy alloys (HEA). Here we present an efficient minimum energy mesh (MEM) method for accurately determining the 2D Peierls potential surface defined by the three ‘easy core’ configurations, to provide a complete picture of the smooth energy landscape of the core structure. The method proceeds by evolving triangulated meshes, i.e., the smooth surfaces with intrinsic parametrization whose dynamics automatically converges to the minimum energy surface in the configurational space. This MEM method accurately determines arbitrary 2D energy landscape, enabling the stress, composition, and short-range order dependence of thermally activated dislocation motion in bcc HEA.