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Title: Critical issues in measuring the mechanical properties of hard films on soft substrates by nanoindentation techniques

Abstract

This study explores the difficulties encountered when using conventional nanoindentation techniques to measure the Young`s modulus and hardness of hard films on soft substrates. In general, the indentation measurement of film/substrate systems is affected by four material properties: the Young`s modulus and hardness of the film, and the Young`s modulus and hardness of the substrate. For the particular case of a hard film on a soft substrate, there is a tendency for the material around the hardness impression to sink-in which results from the large difference in yielding of the two materials. In this study, a model system consisting of NiP on annealed Cu was used to explore the behavior. This system is interesting because the film and substrate have similar Young`s moduli, minimizing the elastic behavior as a variable. In contrast, the hardness of NiP is approximately 7--8 GPa, and that of the annealed copper is less than 1 GPa, providing a factor of 10 difference in the plastic flow characteristics. Experimental results indicate that standard analytical methods for determining the contact depth, hardness and Young`s modulus do not work well for the case of a hard film on a soft substrate. At shallow contact depths, the measured indentationmore » modulus is close to that of the film, but at larger depths sink-in phenomena result in an overestimation of the contact area, and an indentation modulus which is less than the Young`s modulus of both the film and substrate. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) provide critical details of the physical processes involved, and illustrate how the standard data analyses overestimate the true contact area.« less

Authors:
 [1];  [2]
  1. Oak Ridge National Lab., TN (United States)
  2. Rice Univ., Houston, TX (United States). Dept. of Materials Science
Publication Date:
Research Org.:
Oak Ridge National Lab., TN (United States); Oak Ridge Inst. for Science and Education, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
564256
Report Number(s):
ORNL/CP-95655; CONF-971201-
ON: DE98001932; BR: KC0201010; TRN: AHC29804%%133
DOE Contract Number:  
AC05-96OR22464; AC05-76OR00033
Resource Type:
Technical Report
Resource Relation:
Conference: 1997 fall meeting of the Materials Research Society, Boston, MA (United States), 1-5 Dec 1997; Other Information: PBD: [1997]
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; 36 MATERIALS SCIENCE; MECHANICAL TESTS; COMPOSITE MATERIALS; MECHANICAL PROPERTIES; COPPER; NICKEL PHOSPHIDES; YOUNG MODULUS; HARDNESS; EXPERIMENTAL DATA; LAYERS

Citation Formats

Hay, J C, and Pharr, G M. Critical issues in measuring the mechanical properties of hard films on soft substrates by nanoindentation techniques. United States: N. p., 1997. Web. doi:10.2172/564256.
Hay, J C, & Pharr, G M. Critical issues in measuring the mechanical properties of hard films on soft substrates by nanoindentation techniques. United States. doi:10.2172/564256.
Hay, J C, and Pharr, G M. Wed . "Critical issues in measuring the mechanical properties of hard films on soft substrates by nanoindentation techniques". United States. doi:10.2172/564256. https://www.osti.gov/servlets/purl/564256.
@article{osti_564256,
title = {Critical issues in measuring the mechanical properties of hard films on soft substrates by nanoindentation techniques},
author = {Hay, J C and Pharr, G M},
abstractNote = {This study explores the difficulties encountered when using conventional nanoindentation techniques to measure the Young`s modulus and hardness of hard films on soft substrates. In general, the indentation measurement of film/substrate systems is affected by four material properties: the Young`s modulus and hardness of the film, and the Young`s modulus and hardness of the substrate. For the particular case of a hard film on a soft substrate, there is a tendency for the material around the hardness impression to sink-in which results from the large difference in yielding of the two materials. In this study, a model system consisting of NiP on annealed Cu was used to explore the behavior. This system is interesting because the film and substrate have similar Young`s moduli, minimizing the elastic behavior as a variable. In contrast, the hardness of NiP is approximately 7--8 GPa, and that of the annealed copper is less than 1 GPa, providing a factor of 10 difference in the plastic flow characteristics. Experimental results indicate that standard analytical methods for determining the contact depth, hardness and Young`s modulus do not work well for the case of a hard film on a soft substrate. At shallow contact depths, the measured indentation modulus is close to that of the film, but at larger depths sink-in phenomena result in an overestimation of the contact area, and an indentation modulus which is less than the Young`s modulus of both the film and substrate. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) provide critical details of the physical processes involved, and illustrate how the standard data analyses overestimate the true contact area.},
doi = {10.2172/564256},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1997},
month = {12}
}