Homogenization of plastic deformation in heterogeneous lamella structures

ABSTRACT

It has been shown that unlike its constituent nanocrystalline (NC) phase, a heterogeneous lamella (HL) composite comprising NC and coarse-grain layers exhibits greatly improved ductility. To understand the origin of this enhancement, we present a 3D discrete dislocation, crystal plasticity finite element model to study the development of strains across this microstructure. Here we show that the HL structure homogenizes the plastic strains in the NC layer, weakening the effect of strain concentrations. These findings can provide valuable insight into the effects of material length scales on material instabilities, which is needed to design heterogeneous structures with superior properties.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

Our work reveals that the coarse-grain layer of a severely heterogeneous lamella composite homogenizes deformation in the nanocrystalline layer, resulting in the enhanced ductility for which this composite is renowned.

KEYWORDS:

• Dislocations
• statistics
• heterogeneous
• strain gradients
• instability

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the grants from The University of Missouri Research Board. C.Z. is also grateful for the partial support provided by Materials Research Center at Missouri University of Science and Technology. I.J.B. gratefully acknowledges an NSF STEM ADVANCE scholarship from the University of New Hampshire.