Fracture Toughness Measurement of Chromium Nitride Films on Brass

Published

July 1, 2004

Author(s)

M Krishnamurthy, Ivar E. Reimanis, J Berger, Elizabeth S. Drexler

Abstract

Two methods of measureing the fracture toughness of films are critically examined using well-characterized films of CrN and Cr₂N approximately 6(mu)m in thickness bonded to brass. The first method invokes a model developed by Beuth and Klingbeil in which the film fracture stress is related to the fracture energy through an expression that accounts for work hardening of the substrate. The second method is to directly measure the displacement field around the crack tip using electron-beam moire, and subsequently to estimate the crack tip stress intensity factor using full field displacement equations. The films were prepared by magnetron sputtering on brass substrates heat treated at different temperatures, thereby altering the microstructure and hence the substrate yield stress. Unexpectedly, the same films deposited on different substrates lead to very different inplane compressive residual stresses. The effect on crack driving force is discussed and a comparison between these two methods is made. Both techniques agree resonably well, and reveal that CrN exhibits a higher toughness that Cr₂N.

Citation

Journal of the American Ceramic Society

Volume

87

Issue

No. 7

Pub Type

Journals

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Keywords

chromium nitride, electron-beam moire, fracture energy, fracture toughness, residual stresses, thin film

Citation

Krishnamurthy, M. , Reimanis, I. , Berger, J. and Drexler, E. (2004), Fracture Toughness Measurement of Chromium Nitride Films on Brass, Journal of the American Ceramic Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851332 (Accessed July 27, 2024)