The physical origin of observed repulsive forces between general dislocations and twin boundaries in FCC metals : An atom-continuum coupling study

The combination of ultrahigh strength and excellent ductility of nanotwinned materials is rooted in the interaction between dislocations and twin boundaries (TBs). Quantifying the interaction between TBs and dislocations not only offers fresh perspectives of designing materials with high strength and ductility, but also becomes the cornerstone of multiscale modeling of materials with TBs. In this work, an atom-continuum coupling model was adopted to quantitatively investigate the interaction between dislocations and TBs. The simulation shows that the dislocation–TB interaction is much weaker than the interaction between dislocations at the same distance. Simulation of the early stage of dislocation pileups further verifies that the experimentally observed repulsive forces are essentially from the dislocations or kink-like steps on TBs. The interaction between TBs and dislocations with different Burgers vectors was demonstrated referring to the elastic theory of dislocations. With the intrinsic interaction between dislocations and TBs being clarified, this work will promote further development of the multiscale simulation methods, such as discrete dislocation dynamics or phase-field method, of materials with TBs by providing a quantitative description of the interactions between TBs and dislocations.