Characterizing interface dislocations by atomically informed Frank-Bilby theory
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Ruifeng Zhang, Caizhi Zhou, and Irene J. Beyerlein Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
Amit Misra Materials Physics & Applications, The Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (Received 7 November 2012; accepted 1 February 2013)
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.
I. INTRODUCTION
When the spacing between neighboring interfaces is refined down to the nanoscale regime, interface densities increase and interface dynamics dominates. Consequently, interfaces play a critical role in the response of an interface-dense material when exposed to extreme environments such as radiation, elevated temperatures and high strain and strain rates.1–4 Recent atomic scale studies have shown that the behavior of an interface in response to forces or to extrinsic defects is strongly connected to characteristics of their interfacial dislocation network.4–6 The directions of the Burgers vectors of the interfacial dislocations affect its response to an applied interfacial shear stress, determining whether it slides7,8 or it emits dislocations.5,9,10 Such differences have also been found to influence the propensity for deformation twinning11,12 and resistance to shock compression.13 Regarding radiation resistance, the vacancy sink strength has been connected to the number of intersections between distinct interfacial dislocation arrays2,6 and the core of the nonplanar coma)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.34 1646
J. Mater. Res., Vol. 28, No. 13, Jul 14, 2013
http://journals.cambridge.org
Downloaded: 12 Apr 2015
ponent of the Burgers vector.14 Last, the mechanism by which glide dislocations nucleate from the interfa
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