Crystallographic Anisotropy Dependence of Interfacial Sliding Phenomenon in a Cu(16)/Nb(16) ARB (Accumulated Rolling Bonding) Nanolaminate
Résumé
Nanolaminates are extensively studied due to their unique properties such as impact resistance, high fracture toughness, high strength, and resistance to radiation damage. Varieties of nanolaminates are being fabricated to achieve high strength as well as fracture toughness. In this study, one such nanolaminate fabricated through accumulative roll bonded (Cu(16)/Nb(16) ARB nanolaminate, where 16 nm is the layer thickness) is used as a test material. Cu(16)/Nb(16) ARB nanolaminate exhibits crystallographic anisotropy due to the existence of distinct interfaces along the rolling direction (RD) as well as the transverse direction (TD). Nanoindentation was executed using a Berkovich tip with the main axis oriented either along TD or RD of Cu(16)/Nb(16) ARB nanolaminate. Subsequently, height profiles were obtained along the main axis of the Berkovich indent for both TD and RD using scanning Probe Microscopy (SPM), which was later used to estimate the pile-up along RD and TD. TD exhibited more pile-up than RD due to the anisotropy of Cu(16)/Nb(16) ARB interface and material plasticity along TD and RD. An axisymmetric 2D finite element analysis (FEA) was also performed to compare/validate nanoindentation data such as load vs. displacement curves, and pile-up. The FEA simulated load vs. displacement curves matched relatively well with the experimentally generated load-displacement curves, while qualitative agreement was found between simulated pile-up data and experimentally obtained pile-up data. The authors believe that pile-up characterization during indentation is of great importance to documenting anisotropy in nanolaminates.
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