Abstract
We report an exploratory investigation into the cause of shear band formation in multilayer thin-films subject to nanoindentation. The material system considered here is composed of alternating aluminum (Al) and silicon carbide (SiC) nanolayers, atop a silicon (Si) substrate. Finite element models are developed in an attempt to reproduce the shear banding phenomenon observed experimentally. By introducing strain softening into the material model for the hard SiC layers, shear bands can be seen to emerge from the indentation site in the finite element analysis. Broad implications, along with possible directions for future work, are discussed.
Highlights
Multilayer thin-film coatings offer mechanical property benefits beyond what single material films can provide
We have demonstrated that strain softening of the hard layer after yielding is a key factor in shear band formation in thinfilm multilayers
The shape and prominence of shear banding are dependent on the relative stress–strain curves of each material in the structure
Summary
Multilayer thin-film coatings offer mechanical property benefits beyond what single material films can provide. Multilayered configurations introduce complex internal stress and strain behaviors, which may affect the derived mechanical property values in ways not yet understood (Bhattacharyya et al, 2011; Jamison and Shen, 2016). Prior work in this area has investigated elastic modulus, hardness, plastic deformation during unloading, imperfect layer geometry, and delamination (Chawla et al, 2008; Tang et al, 2008, 2010; Wang et al, 2012; Jamison and Shen, 2016). The present exploratory work focuses on attempting shear band initiation in finite element models by incorporating strain softening of the SiC layers
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