Three-dimensional phase field microelasticity modeling and simulation capable of representing core structure and elastic interactions of dislocations are used to study a glide dislocation transmission across a coherent sliding interface in face-centered cubic metals. We investigate the role of the interface sliding process, which is described as the reversible motion of interface dislocation on the interfacial barrier strength to transmission. Numerical results show that a wider transient interface sliding zone develops on the interface with a lower interfacial unstable stacking fault energy to trap the glide dislocation leading to a stronger barrier to transmission. The interface sliding zone shrinks in the case of high applied stress and low mobility for the interfacial dislocation. This indicates that such interfacial barrier strength might be rate dependent. We discuss the calculated interfacial barrier strength for the Cu/Ni interface from the contribution of interface sliding comparable to previous atomistic simulations.
Revealing the long-range elastic interaction and short-range core reaction between intersecting dislocations is crucial to the understanding of dislocation-based strain hardening mechanisms in crystalline solids. Phase field model has shown great potential in modeling dislocation dynamics by both employing the continuum microelasticity theory to describe the elastic interactions and incorporating the γ-surface into the crystalline energy to enable the core reactions. Since the crystalline energy is approximately formulated by linear superposition of interplanar potential of each slip plane in the previous phase field model, it does not fully account for the reactions between dislocations gliding in intersecting slip planes. In this study, an improved phase field model of dislocation intersections is proposed through updating the crystalline energy by coupling the potential of two intersecting planes, and then applied to study the collinear interaction followed by comparison with the previous simulation result using discrete dislocation dynamics. Collinear annihilation captured only in the improved phase field model is found to strongly affect the junction formation and plastic flow in multislip systems. The results indicate that the improvement is essential for phase field model of dislocation intersections.
INTRODUCTIONInteractions between dislocations gliding in intersecting slip planes play fundamental roles in the strain hardening during plastic deformation of crystalline materials.1-4 Dislocation intersections lead to the formation of dislocation junctions in minimum energy configurations. In face-centered cubic (FCC) crystals, the sessile junction known as Lomer-Cottrell lock 5,6 is assumed to be the most stable barrier to further dislocation motion in the traditional view.1,3 However, Madec and co-workers 7 reported that the interaction between two intersecting dislocations with collinear Burgers vectors is the strongest of all dislocation reactions. Previous modeling and simulations 7-24 on investigating the dislocation intersections emphasized the importance of the interaction details between individual dislocations, including not only the long-range elastic interactions but also the short-range core reactions. Most of these researches suggested that the dislocation interactions can be studied by multiscale approaches, where the discrete dislocation dynamics (DDD) based on continuum elasticity theory deals with the long-range elastic attraction or repulsion, and atomistic simulations the short-range reaction rules.9 Different from the DDD techniques that require priori rules as inputs, 10 another simulation method also based on continuum elastic theory called phase field model (PFM) 25-30 can straightforwardly account for the effects of short-range core reactions by incorporating the generalized stacking fault energy (γ-surface) 11 from atomistic or first principle calculations, such as dislocation dissociation. [31][32][33][34][35] With this advantage, the PFM model of dislocation shows great potent...
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