Multi-scale modeling of dislocation-precipitate interactions in Fe: from molecular dynamics to discrete dislocations

摘要

The stress-driven motion of dislocations in crystalline solids, and thus theensuing plastic deformation process, is greatly influenced by the presence orabsence of various point-like defects such as precipitates or solute atoms.These defects act as obstacles for dislocation motion and hence affect themechanical properties of the material. Here we combine molecular dynamicsstudies with three-dimensional discrete dislocation dynamics simulations inorder to model the interaction between different kinds of precipitates and a$\frac{1}{2}\langle 1 1 1\rangle$ $\{1 1 0\}$ edge dislocation in BCC iron. Wehave implemented immobile spherical precipitates into the ParaDis discretedislocation dynamics code, with the dislocations interacting with theprecipitates via a Gaussian potential, generating a normal force acting on thedislocation segments. The parameters used in the discrete dislocation dynamicssimulations for the precipitate potential, the dislocation mobility, shearmodulus and dislocation core energy are obtained from molecular dynamicssimulations. We compare the critical stresses needed to unpin the dislocationfrom the precipitate in molecular dynamics and discrete dislocation dynamicssimulations in order to fit the two methods together, and discuss the varietyof the relevant pinning/depinning mechanisms.