Interface-dominated plasticity and kink bands in metallic nanolaminates

TL;DR

This paper uses a mesoscale field dislocation mechanics framework to model and analyze kink-band formation in metallic nanolaminates, providing insights into interface effects and deformation mechanisms through simulations.

Contribution

It introduces a minimal finite element model incorporating interface conditions to simulate kink-band formation in Cu-Nb nanolaminates, linking theory with experimental observations.

Findings

Kink bands form under layer parallel compression consistent with experiments.

Interface conditions enable plastic flow communication across laminate boundaries.

Parametric studies reveal factors influencing kink-band orientation and formation.

Abstract

The theoretical and computational framework of finite deformation mesoscale field dislocation mechanics (MFDM) is used to understand the salient aspects of kink-band formation in Cu-Nb nano-metallic laminates (NMLs). A conceptually minimal, plane-strain idealization of the three-dimensional geometry, including crystalline orientation, of additively manufactured NML is used to model NMLs. Importantly, the natural jump/interface condition of MFDM imposing continuity of (certain components) of plastic strain rates across interfaces allows theory-driven `communication' of plastic flow across the laminate boundaries in our finite element implementation. Kink bands under layer parallel compression of NMLs in accord with experimental observations arise in our numerical simulations. The possible mechanisms for the formation and orientation of kink bands are discussed, within the scope of our idealized framework. We also report results corresponding to various parametric studies that provide preliminary insights and clear questions for future work on understanding the intricate underlying mechanisms for the formation of kink bands.