Characterization of Cu-Ni multilayer coatings by nanoindentation and atomic force microscopy

Barshilia, Harish C and Rajam, KS (2001) Characterization of Cu-Ni multilayer coatings by nanoindentation and atomic force microscopy. Technical Report. National Aerospace Laboratories.

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Cu-Ni multilayer coatings prepared by RF magnetron sputtering process have been characterized using X-ray diffraction (XRD), nanohardness tester (NHT) and atomic force microscopy (AFM) techniques. Films deposited under certain deposition conditions showed appearance of satellite reflections around the principal reflection in the XRD data indicating the formation of Superlattice structure. Nanohardness measurements have been performed for the films prepared under different deposition conditions, e.g., modulation wavelength (Λ), copper to nickel thickness ratio (tCu/tNi) and substrate temperature. Nanohardness data reveal that the hardness is enhanced by a factor of ~2.5 times that of rule of mixtures value. This enhancement in hardness occurs over limited range in Λ. Our results also indicate that the hardness also depends on copper to nickel thickness ratio and for tCu/tNi  0.30 the films exhibit maximum hardness. The hardness increases almost linearly with substrate temperature up to 200ºC and saturates at 250ºC. No considerable change in the hardness has been observed after vacuum annealing of the coatings. Imaging of the residual imprints by AFM reveal pile-up formation after indentation. The extent of pile-up, a measure of plastic flow of the material, depends on the preparation conditions of the multilayer coatings.

Item Type: Monograph (Technical Report)
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
PHYSICS > Physics(General)
Depositing User: Dr. Harish C. Barshilia
Date Deposited: 25 Oct 2011 04:04
Last Modified: 25 Oct 2011 04:04

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