Modes of strain accommodation in Cu-Nb multilayered thin film on indentation and cyclic shear

Mayur Pole, Zexi Lu, Tanvi Anil Ajantiwalay, Matthew Olszta, Shalini Tripathi, Anqi Yu, Hardeep Mehta, Tianhao Wang, Xiaolong Ma, Arun Devaraj, Bharat Gwalani*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

Abstract

Two-phase layered thin films with a high density of semi-coherent interfaces exhibit excellent mechanical properties and thermal stability. In this study, a magnetron-sputtered Cu-Nb dual-layered thin film (∼500 nm for Cu and ∼150 nm for Nb) having an amorphous interface between Cu and Nb with a high density of aligned growth twins in Cu is subjected to severe surface deformation. The material is loaded using indentation and cyclic shear under tribological testing. The strain accommodation in the subsurface microstructure after deformation varies based on the local structure and deformation mode. Grain refinement and crack formations in the stressed region of the Nb layer and localized crystallization of the amorphous interface are observed after indentation and scratch testing. Pronounced detwinning of growth twins in the Cu layer under the cyclic shear strain leaves large dislocations sites and loops which are observed both by high-resolution transmission electron microscopy and experiment-guided molecular dynamic (MD) simulations. Our simulations provided insights into understanding the pathway for the detwinning process under cyclic shear loading. © 2023 Elsevier B.V. All rights reserved.

Original languageEnglish
Article number102712
JournalSurfaces and Interfaces
Volume37
Online published7 Feb 2023
DOIs
Publication statusPublished - Apr 2023
Externally publishedYes

Funding

This research was supported by the Laboratory Directed Research and Development (LDRD) Solid Phase Processing Science Initiative (SPPSi), at the Pacific Northwest National Laboratory (PNNL). Partial TEM experiments of this work were conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research and located at PNNL. PNNL is a multiprogram national laboratory operated by Battelle Memorial Institute for the U.S. Department of Energy (DOE) under contract No. DE-AC05–76RL01830. BG would like to acknowledge the start-up funds provided by NC State University. This research was supported by the Laboratory Directed Research and Development (LDRD) Solid Phase Processing Science Initiative (SPPSi) , at the Pacific Northwest National Laboratory (PNNL). Partial TEM experiments of this work were conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research and located at PNNL. PNNL is a multiprogram national laboratory operated by Battelle Memorial Institute for the U.S. Department of Energy (DOE) under contract No. DE-AC05–76RL01830 . BG would like to acknowledge the start-up funds provided by NC State University.

Research Keywords

  • Coefficient of friction
  • Cu-Nb layered thin films
  • Cyclic shear
  • Deformation mechanism
  • Detwinning

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