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Effect of Grain Boundaries and Indentation Load on the Electrical Properties of Nickel Base Super-alloys

Published online by Cambridge University Press:  17 March 2011

Kimberly Pinkos ,
Celestina Laboy  and
Rosario A. Gerhardt
Kimberly Pinkos
Affiliation:
School of Materials Science and Engineering Georgia Institute of Technology, Atlanta, GA 30332-0245
Celestina Laboy
Affiliation:
School of Materials Science and Engineering Georgia Institute of Technology, Atlanta, GA 30332-0245
Rosario A. Gerhardt
Affiliation:
School of Materials Science and Engineering Georgia Institute of Technology, Atlanta, GA 30332-0245
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Abstract

We have used impedance spectroscopy to evaluate the effect of the presence of grain boundaries and plastic deformation, as caused by hardness indentation, on the electrical response of several commercial nickel base super-alloys at room temperature. These alloys consist of a mostly nickel matrix that contains small precipitates of intermetallic phases such as Ni3Al or Ni3Ti(often referred to as gamma prime) as a reinforcing phase. Measurements were made as point contacts so that data could be tracked from point to point. Results indicate that the grain boundaries tend to have higher conductivities than the individual grains in most cases. It is speculated that this is due to the boundary regions having a different compositional profile than the center of the grains(as determined by gamma prime size, shape and distribution). Hardness indentation, on the other hand, had a more dramatic effect, by causing the magnitude of the imaginary impedance to change in size as well as position. Complementary microscopy results are included as supporting evidence for the effects discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 699: Symposium R – Electrically Based Microstructural Characterization III , 2001 , R2.5
Copyright
Copyright © Materials Research Society 2002

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