ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Two methods of measuring the fracture toughness of films are critically examined using well-characterized films of CrN and Cr2N ˜6 μm 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 molrè and, subsequently, to estimate the crack-tip stress Intensity factor using full-field-displacement equations. The films are prepared by magnetron sputtering on brass substrates heat-treated at various temperatures, thereby altering the microstructure and, hence, the substrate yield stress. Unexpectedly, the same films deposited on various substrates lead to very different in-plane compressive residual stresses. The effect on crack-driving force is discussed, and a comparison between these two methods is made. Both techniques agree reasonably well and reveal that CrN exhibits a higher toughness than Cr2N.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1551-2916.2004.tb20097.x
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