Phase Field Method to the Interaction of Phase Transformations and Dislocations at Nanoscale

Javanbakht, M.; Levitas, V. I.

doi:10.22060/mej.2017.11892.5209

Phase Field Method to the Interaction of Phase Transformations and Dislocations at Nanoscale

Document Type : Research Article

Authors

M. Javanbakht ¹
V. I. Levitas ²

¹ Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran

² Iowa State University, Departments of Mechanical and Aerospace Engineering, Ames, IA, USA

10.22060/mej.2017.11892.5209

Abstract

In this paper, a new phase field method for the interaction between martensitic phase
transformations and dislocations is presented which is a nontrivial combination of the most advanced
phase field methods to phase transformations and dislocation evolution. Some of the important points in
the model are the multiplicative decomposition of deformation gradient into elastic, transformational and
plastic parts, defining a proper energy to satisfy thermodynamic equilibrium and instability conditions,
including phase-dependent properties of dislocations. The system of equations consists of coupled
elasticity and phase field equations of phase transformations and dislocations. Finite element method
is used to solve the system of equations and applied to study the growth and arrest of martensitic plate
and the evolution of dislocations and phase in a nanograined material. It is found that dislocations play
a key role in eliminating the driving force of the plate growth and their arrest which creates athermal
friction. Also, the dual effect of plasticity on phase transformations is revealed; due to dislocations
pile-up and its stress concentration, the phase transformation driving force increases and consequently,
martensitic nucleation occurs. On the other hand, the dislocation nucleation results in decreasing the
phase transformation driving force and consequently, the phase transformation is suppressed.

Highlights

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Keywords

References