Microscopic Phase Field Modeling of Shear-Dominated Processes during Phase Transformation and Plastic

C. Shen, J. Li, and Y. Wang

Department of Materials Science and Engineering

Ohio State University

Because of its flexibility in treating microstructures of arbitrary geometries, the phase field approach has been widely used in describing microstructures consisting of various types of extended defects. Typical examples include dislocations, homo- and hetero-phase interfaces, and ferromagnetic and ferroelectric domain walls. The elastic energy formulation in the phase field method is based on anisotropic continuum elasticity implemented using exact 3-D Green‚s function to account for the long-range interactions, which forms a super set of the traditional Peierls model that has been the cornerstone of modern nanomechanics. In this presentation, we employ ab initio calculations as the sole inputs and show quantitatively that the microscopic phase field model of dislocations is a 3D generalization of the Peierls model. When applied to straight dislocations, a complete agreement of the phase field model with the Peierls model for core structures has been achieved using the same set of ab initio data of generalized stacking fault (GSF) energies. Three examples of applications of the microscopic phase field models will be discussed: (a) the energy and sliding resistance of Peierls grain boundaries (small angle grain boundaries consisting of regular dislocation networks), (b) the initiation and growth of martensite, and (c) the shearing of gamma prime precipitates in Ni-base superalloys during creep deformation.