Journal of Materials Research

Articles

Continuous electrical in situ contact area measurement during instrumented indentation

Lei Fanga1, Christopher L. Muhlsteina2 c1, James G. Collinsa2, Amber L. Romascoa2 and Lawrence H. Friedmana3

a1 Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802

a2 Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802

a3 Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802

Abstract

The primary tool for mechanical characterization of surfaces and films is instrumented indentation using the Oliver-Pharr data analysis method. However, this method measures contact area between the indenter and sample indirectly, thus confounding instrumented indentation tests when characterizing dynamic properties, thin films, and materials that “pileup” around the indenter. Here, we demonstrate an electrical technique to continuously measure the in situ contact area by relating nonlinear electrical contact current–voltage (I–V) curves to the instantaneous contact area. Using this approach, we can obtain hardness as a continuous function of applied force.

(Received January 25 2008)

(Accepted June 4 2008)

Key Words:

  • Cu;
  • Electrical properties;
  • Hardness

Correspondence:

c1 Address all correspondence to this author. e-mail: clm28@psu.edu

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