Cohesive laws for shearing of iron/precipitate interfaces

The behaviour of 11 differently oriented iron-precipitate interfaces under a shear load is studied with molecular dynamics simulations. We find that the behaviour depends not only on the interface orientation but also on the shear direction. Furthermore, for many interfaces the presence of a dislocation at the interface triggers a structure change in the interface, and with that completely modifies the shear behaviour. Several interface characteristics are inspected for their possibly decisive influence on the observed loading curves. However, none of these characteristics is found to correlate conclusively with the shear behaviour of the different interfaces. This indicates that actual shear behaviour is rooted in a deeper level of complexity than just depending on the properties of the initial interface. Clearly the time evolution of the interface during shearing is crucial. From the observations a comprehensive cohesive law is derived that represents the shear behaviour for every interface and for both shear directions. This cohesive law can be used in numerical methods at a larger length sale, such as discrete dislocation plasticity.