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Instrumented microindentation of nanoporous alumina films

Publication ,  Journal Article
Gall, K; Liu, Y; Routkevitch, D; Finch, DS
Published in: Journal of Engineering Materials and Technology
January 1, 2006

We examine the mechanical behavior of anodic alumina thin films with organized nanometer-scale porosity. The cylindrical pores in the alumina film are arranged perpendicular to the film thickness in a near-perfect triangular lattice. The films used in this work had pore diameters ranging from 35 to 75 nm, and volume fractions ranging from 10% to 45%. Films with both amorphous and crystalline structures were considered. Mechanical properties of the thin films were studied using an instrumented indentor to measure the force-depth response of the films during indentation or the force-deflection response of micromachined beams in bending. The films showed increasing hardness/ modulus with a decrease in pore volume fraction or transformation from amorphous to a polycrystalline alpha-alumina phase. The asymmetric films show higher hardness and modulus on their barrier side (with closed pores) relative to their open pore side. The force-depth response, measured with a spherical ball indentor, demonstrates fairly good agreement with an elastic Hertzian contact solution. The force-depth response, measured with a sharp Vickers indentor, shows an elastoplastic response. Microcracking at the corners of sharp indentations was not observed in amorphous nanoporous films, and rarely in harder, crystalline nanoporous films. High-resolution scanning electron microscopy revealed a collapse of the nanoporous structure beneath the indentor tip during sharp indentation. The results are discussed in light of continuum-based models for the elastic properties of porous solids. In general, the models are not capable of predicting the change in modulus of the films, given pore volume fraction and the properties of bulk crystalline alumina. Copyright © 2006 by ASME.

Duke Scholars

Published In

Journal of Engineering Materials and Technology

DOI

ISSN

0094-4289

Publication Date

January 1, 2006

Volume

128

Issue

2

Start / End Page

225 / 233

Related Subject Headings

  • Materials
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0910 Manufacturing Engineering
 

Citation

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ICMJE
MLA
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Gall, K., Liu, Y., Routkevitch, D., & Finch, D. S. (2006). Instrumented microindentation of nanoporous alumina films. Journal of Engineering Materials and Technology, 128(2), 225–233. https://doi.org/10.1115/1.2172626
Gall, K., Y. Liu, D. Routkevitch, and D. S. Finch. “Instrumented microindentation of nanoporous alumina films.” Journal of Engineering Materials and Technology 128, no. 2 (January 1, 2006): 225–33. https://doi.org/10.1115/1.2172626.
Gall K, Liu Y, Routkevitch D, Finch DS. Instrumented microindentation of nanoporous alumina films. Journal of Engineering Materials and Technology. 2006 Jan 1;128(2):225–33.
Gall, K., et al. “Instrumented microindentation of nanoporous alumina films.” Journal of Engineering Materials and Technology, vol. 128, no. 2, Jan. 2006, pp. 225–33. Scopus, doi:10.1115/1.2172626.
Gall K, Liu Y, Routkevitch D, Finch DS. Instrumented microindentation of nanoporous alumina films. Journal of Engineering Materials and Technology. 2006 Jan 1;128(2):225–233.

Published In

Journal of Engineering Materials and Technology

DOI

ISSN

0094-4289

Publication Date

January 1, 2006

Volume

128

Issue

2

Start / End Page

225 / 233

Related Subject Headings

  • Materials
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0910 Manufacturing Engineering