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Incipient yielding behavior during indentation for gold thin films before and after annealing

Publication ,  Journal Article
Miller, DC; Talmage, MJ; Gall, K
Published in: Journal of Materials Research
October 1, 2006

We studied the deformation mechanisms and mechanics during indentation of polycrystalline gold thin films at depths below 100 nm. The measured material hardness decreased from 2.1 ± 0.1 to 1.7 ± 0.1 GPa after annealing for 4 h at 177 °C. Upon closer inspection, the hardness trends in the gold thin films were discovered to vary according to the indentation depth. At nanometer depths, the material hardness was quantified using multiple parameters, some of which were independent of the area calibration for the tip. The annealed specimen was very "hard" at low indentation depths, relatively soft at moderate indentation depths, and finally harder until the grain-size limit was reached. The as-deposited specimen demonstrated a relatively continuous harness trend as function of indentation depth, exhibiting monotonic convergence to Hall-Petch limited behavior. Discrete displacement jump events (excursions or "pop-ins") were frequently observed for the annealed specimen but not for the as-deposited specimen. Variation in hardness, excursion activity, and displacement during the hold at maximum load was observed according to the applied loading, which was parametrically varied at constant strain rates. Hardness results are explained in terms of the population and evolution of defects present within the specimens. The population of point defects is also influential, and critical thermal fluctuations, as well as the thermally activated process of diffusion, are believed to influence hardness at the specimen's free surface and further into its volume. After converging to a monotonic trend (proper tip engagement), the modulus of the gold was measured to be 106.0 ± 12.9 and 101.3 ± 6.0 GPa for the respective Au/Cr/Si specimens. These values exceeded predictions from the aggregate polycrystalline material theory, a representation used to estimate results for anisotropic single crystals. Exaggerated modulus measurements are explained as the result of the contribution of modulus mismatch with the substrate, pileup at the indentor tip, residual stress in the films, and crystallographic anisotropy of the gold. © 2006 Materials Research Society.

Duke Scholars

Published In

Journal of Materials Research

DOI

ISSN

0884-2914

Publication Date

October 1, 2006

Volume

21

Issue

10

Start / End Page

2480 / 2492

Related Subject Headings

  • Materials
  • 5104 Condensed matter physics
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0204 Condensed Matter Physics
 

Citation

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Miller, D. C., Talmage, M. J., & Gall, K. (2006). Incipient yielding behavior during indentation for gold thin films before and after annealing. Journal of Materials Research, 21(10), 2480–2492. https://doi.org/10.1557/jmr.2006.0303
Miller, D. C., M. J. Talmage, and K. Gall. “Incipient yielding behavior during indentation for gold thin films before and after annealing.” Journal of Materials Research 21, no. 10 (October 1, 2006): 2480–92. https://doi.org/10.1557/jmr.2006.0303.
Miller DC, Talmage MJ, Gall K. Incipient yielding behavior during indentation for gold thin films before and after annealing. Journal of Materials Research. 2006 Oct 1;21(10):2480–92.
Miller, D. C., et al. “Incipient yielding behavior during indentation for gold thin films before and after annealing.” Journal of Materials Research, vol. 21, no. 10, Oct. 2006, pp. 2480–92. Scopus, doi:10.1557/jmr.2006.0303.
Miller DC, Talmage MJ, Gall K. Incipient yielding behavior during indentation for gold thin films before and after annealing. Journal of Materials Research. 2006 Oct 1;21(10):2480–2492.
Journal cover image

Published In

Journal of Materials Research

DOI

ISSN

0884-2914

Publication Date

October 1, 2006

Volume

21

Issue

10

Start / End Page

2480 / 2492

Related Subject Headings

  • Materials
  • 5104 Condensed matter physics
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0204 Condensed Matter Physics