The role of interfacial misfit on the interaction between dislocation and heterogeneous interface in Cu/Fe bimetal laminated composites

Abstract

Heterogeneous interface can increase the strength of bimetal laminated composites (BLCs) significantly through interaction effect with dislocation line, and the interfacial misfit plays an important role during interaction process. The present study performed discrete dislocation dynamics on the Cu/Fe BLC to investigate the interaction mechanisms between dislocation and heterogeneous interface with or without misfit. The interfacial misfit dislocations were characterized and stress/strain fields were calculated by TEM and geometric phase analysis. Different dislocations of single dislocation (SD), dislocation pair (DP) and dislocation array (DA) were located at the interface to investigate the interactions between them and dislocation line inside crystal. The results show that one side of SD promotes the motion of dislocation line while the other side prevents its motion. The positive stress field at the center of the DP formed by the superposition of two dislocations accelerates the motion of dislocation line, while the negative stress field has obstruction effect. DA consisting of periodic dislocations distributed at the interface has strong pinning effect on the movement of dislocation line inside crystal, making it difficult to cross the interface. The strengthening effect is more significant when the interface and misfit dislocations act as strong obstruction roles. These findings suggest that the formation of misfit dislocations due to large differences in lattice constant has large strengthening effect on BLCs.