Suppressing shear band instability in crystal/glass nanolaminates with high strength and plasticity

Overview & Synopsis

Crystal/glass nanolaminates (NLs) present mutually exclusive mechanical properties by combining the strength of the glass phase with the ductility of the crystalline phase. For instance, optimizing the layers thickness of Cu/CuZr NLs suppresses shear band instability and promotes co-deformation, achieving a strength of 2.5 GPa and 40% plasticity in compression [1,2]. However, the role of deformation mechanisms and interface interactions in suppressing shear band instability remains incompletely understood. Additionally, BCC/glass NLs remain largely unexplored despite their proven potential to present high strength and ductility [3]. Here, we synthesized 2 µm-thick Fe/Zr40Cu60 (crystal/glass) NLs by magnetron co-sputtering. We varied the Zr40Cu60 thickness (10-90 nm), keeping the Fe at 10 nm, to investigate the size-dependent deformation-mode transition. In a second approach, we varied the bilayer period between 20-80 nm at equal volume fractions, tuning the interface density. This study aims to establish architectural and interface engineering strategies to suppress shear band instability. The hardness of the Fe/Zr40Cu60 NLs exceeds individual layer values, reaching 9.6 GPa for the 10/10 nm NLs due to the sharp interfaces blocking the shear band. Micropillar compression tests reveal that thicker Zr40Cu60 layers (90 nm) lead to localized shear bands, whereas thinner layers show delayed shear band instability. Combining interface and architecture effects, 20/20 nm exhibits an exceptional 45% compressive plasticity and yield strength of 1.96 GPa due to effective shear band instability suppression. Overall, our findings provide insights into the nanoengineering of crystal/glass NLs interfaces and architectures to enhance their mechanical properties effectively. [1] J. Y. Kim et al., Adv Funct Mater, vol. 21, no. 23, Dec. 2011. [2] W. Guo et al., Acta Mater, vol. 80, 2014. [3] F. Qin et al., Mater. Sci. Eng. A, vol. 891, 2024.