Characterizing interface dislocations by atomically informed Frank-Bilby theory

Abstract

Semicoherent interfaces containing discrete dislocations are more energetically favorable than those containing continuous distributions because of lower chemical energy. The classical Frank-Bilby theory provided a way to determine the interface Burgers vectors content but could not effectively predict the characteristics of discrete dislocations. Atomistic simulations provide insights into analyzing the characteristics of discrete dislocations but the analysis is often disturbed by the reaction of interface dislocations. By combining the classical Frank-Bilby theory and atomistic simulations, an atomically informed Frank-Bilby theory proposed in this work can overcome shortcomings in both the classic Frank-Bilby theory and atomistic simulations, and enable quantitative analysis of interface dislocations. The proposed method has been demonstrated via studying two typical dissimilar metallic interfaces. The results showed that Burgers vectors of interface dislocations can be well defined in a Commensurate/Coherent Dichromatic Pattern (CDP) and the Rotation CDP (RCDP) lattices. Most importantly, the CDP and RCDP lattices are not simply a geometric average of the two natural lattices, that is the lattice misfit and the relative twist take the nonequal partition of the misfit strain and the twist angle.

Spiral Patterns of Dislocations at Nodes in (111) Semi-coherent FCC Interfaces

“…The distance between nodes can be calculated according to Frank-Bilby theory23. The critical distance corresponding to the disappearance of the SP feature is 2.2 nm according to the expanded node in Cu/Ni interface.…”

“…Such interfaces arise, for example, in epitaxial layers, precipitation, and both diffusional and diffusionless displacive phase transformations1. A superposed network of interface dislocations accommodates the attendant coherency strains in the adjacent crystals23. Atomistic simulations combining in situ / ex situ transmission electron microscopy have provided insights into understanding the properties and their dependence on interface dislocation structures.…”

Interface structures and twinning mechanisms of twins in hexagonal metals

“…We focus on the PP interface because of its lower interface energy. Supporting this view, the pattern of Figure 10 A reference CDP for the PP case is constructed in Figure 10(a), where the coherency strain is partitioned between the crystals, as indicated in the rotated CDP [17,86,87] defined in Figure 10(b). The PP interface has a relative rotation of unit cells of 90°.…”

Glide dislocation nucleation from dislocation nodes at semi-coherent {1 1 1} Cu–Ni interfaces

“…These junctions formed via a reaction between intersecting interfacial dislocations under mechanical loading [28][29][30]. The interfaces in these cases were a stepped Kurdjumov-Sachs interface [30,34,35] or a twisted Nishiyama-Wasserman interface [36].…”