Kink mechanism in Cu/Nb nanolaminates explored by in situ pillar compression

Interface-Dominated Plasticity and Kink Bands in Metallic Nanolaminates

“…GNDs are generated in the domain due to the inhomogeneity in the material response after yielding from the material inhomogeneity of the laminate structure in NMLs, and the imposition of jump condition on plastic strain rate at the interfaces. It is evident from Figure 3 that the kink-band forms in accordance with the experimental observations in [4,8]. It is evident that the deformation field localizes within the band, and the kink band is inclined (not perpendicular) to the layering in NML as shown in Figure 1.…”

“…The interface conditions in MFDM impose continuity of certain components of the total plastic strain rate, which models continuous plastic flow across the laminate interfaces. We consider a 'minimal' model setup in considering 3 co-planar slip systems for each material in the bi-metallic laminate structure and show that kink bands are formed in qualitative accord with the experimental observations of [4,8]. We also report on other studies within this idealized setup and discuss whether kink bands form or not for different cases.…”

“…Figure 2b,c shows the true and engineering stress-strain curve obtained from our simulation and the experimentally obtained stress-strain curve from [8], and it is clear that the numerically obtained stress-strain curves do not match with the experimental ones. The yield strength obtained from our simulations is between 0.45-0.5 GPa, while in the experimental results from [8], it is close to 1.0 GPa. The strain-hardening response is more prominent in our numerical result as compared to the experimental observation, where after yielding it stays at a more-or-less constant level of stress.…”

“…It was reported there that the samples with layer thickness greater than 250 nm deform homogeneously, while the deformation behavior of samples with thicknesses 65 or 30 nm was inhomogeneous, and enhanced plastic deformation was observed after yield at a more-or-less constant load [4]. Recently, Zhang et al [8] investigated the kink band formation process in Cu/Nb NMLs via in situ micropillar compression along the layer-parallel direction in a scanning electron microscope (SEM). It was reported that after the onset of kinking, dislocations active on the slip systems nearly parallel to the interface in NMLs are responsible for the band evolution.…”

Synchronized Formation of Kink Bands in Al/Al₂Cu Mille-Feuille Structured Alloy

“…2022) Such slow kink growth is also observed in Zn single crystals 22) and Cu/Nb nanolaminates. 23) The difference in growth rate suggests a different mechanism of kink band formation and propagation, which requires further studies. The micro kink-bands appeared only in the lower central part of the specimen, and was not observed in other areas.…”