Loss of interface coherency around a misfitting spherical inclusion

Abstract

The interfaces between different materials can be coherent (heteroepitaxial), semi-coherent or incoherent. A semi-coherent interface is one in which the misfit between the two phases is partially or fully accommodated by discrete interfacial dislocations. A precipitate-matrix interface may undergo a transition from coherent to semi-coherent through dislocation nucleation or interactions with pre-existing dislocations during plastic deformation. Dislocation-precipitate interactions can also be modified significantly by the degree of coherency of the interface. In this study, we examine how plasticity mediates the change from coherent to semi-coherent interfaces in the case of a misfitting spherical particle, i.e. how the matrix dislocations relax the misfit of the particle and form dislocation structures on the particle-matrix interface. Various stable dislocation structures on the semi-coherent particles are studied. We also examine how dislocation-particle interactions are influenced by the change in the particle from coherent to semi-coherent. These simulations are performed using a three-dimensional level set dislocation dynamics method. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.