Dislocation impacts on iron/precipitate interfaces under shear loading

Molecular dynamics simulations are performed to obtain a better understanding of the interactions of single dislocations and dislocation pile-ups with interfaces between iron and a precipitate. The material properties of the precipitate material and the iron-precipitate interaction are varied to understand the influence of interface structure, interface strength and precipitate stiffness on these interactions under shear loading. Our main findings are: (1) the interface adhesion is determined by a combination of the atomic interactions across the interface and the interface structure, (2) the interface structure is the key factor determining the dislocation accommodation capability of the interface: very strong semi-coherent interfaces do accommodate dislocations, while only very weak coherent interfaces are capable of doing this, and (3) a strong precipitate prevents slip transfer into the precipitate. Results of this study combined with those of a forthcoming study under tensile loading can be used to improve the description of interface decohesion in existing larger-scale models, such as discrete dislocation plasticity. (paper)