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.