Strength and plastic deformation behavior of nanolaminate composites with pre-existing dislocations

M Damadam and S Shao and I Salehinia and I Mastorakos and G Ayoub and HM Zbib, COMPUTATIONAL MATERIALS SCIENCE, 138, 42-48 (2017).

DOI: 10.1016/j.commatsci.2017.06.016

Pre-existing dislocations (PED) are ubiquitous inside crystalline lattices which in turn affect the yield stress and the process of plastic deformation. Hence, understanding the onset of dislocations motion and interaction is critical in modifying or designing new materials with advanced properties so that their mechanical behavior approach realistic conditions. One such family of new materials is the ceramic/ metallic nanolaminates. In this work, we have investigated the effect of pre-existing dislocations on the mechanical behavior of NbC/Nb nanolaminates using molecular dynamics simulations. Upon unloading at different strains from stress-strain curve of 3 nm NbC/7 nm Nb sample, we were able to generate structures with various pre-existing dislocation densities inside the layers. Uniaxial loadings parallel to the interface at two different temperatures (10 K and 300 K) were performed on each structure. Also, the yield locus was determined at 300 K by applying biaxial in-plane loading and fitted with a general flow potential to be used in macroscale analysis. Finally, the tension- compression asymmetry (TCA) was investigated for the structures with pre-existing dislocations along two different in-plane loading directions. (C) 2017 Elsevier B.V. All rights reserved.

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