Evolution of Interfacial Dislocation Networks in Particle-Strengthened Alloy Systems During High Temperature Creep: A Discrete Dislocation Dynamics Study

In particle strengthened alloy systems, e.g. precipitation strengthened Ni-base superalloys, high-temperature creep is dictated by the motion of dislocations and their interactions with the particles. In particular, the steady state creep rate at low stress and high temperature is primarily governed by the evolution of interfacial dislocation networks which form as a result of dislocation-particle interactions. Development of back-stress during creep may be attributed to evolution of these networks. To understand the role of dislocation-particle interactions on the evolution of back stress, we have performed systematic discrete dislocation dynamics simulations (using a modified ParaDis code) in three dimensions using a model system composed of coherent cuboidal particles embedded in a matrix. Our model takes into account forces on the dislocations arising due to order strengthening. Our results show that the interparticle spacing critically controls the onset of dynamic recovery process during creep. Also the interparticle spacing and applied stress strongly affects the evolution of interfacial dislocation network.