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发帖数: 5 | 1 Guangfeng Zhao, Ming Liu and Fuqian Yang, The effect of an electric current
on the nanoindentation behavior of tin, Acta Materialia 60 (2012) 3773-3782
Abstract
Electrical–thermal–mechanical interactions determine the reliability and
performance of microelectromechanical devices and systems.
Using the nanoindentation technique the effect of an electric current
on the indentation deformation of Sn strips was studied for an
indentation load in the range 50–200 lN. During the indentation an electric
current density in the range 993.05–4087.89 A cm2
was
passed through the Sn strips, which introduced electrical–thermal–
mechanical interactions. The experimental results showed that the
reduced contact modulus decreased with increasing electric current density.
For an electric current density less than 4087.89 A cm2
the decrease in the reduced contact modulus with increasing electric current
density was mainly controlled by Joule heating due to an
electrothermal interaction. The electrothermal interaction caused surface
softening of the Sn strips. A simple relation is proposed to
describe the dependence of the reduced contact modulus on the electric
current density. The indentation hardness decreased with increas-
ing indentation load, showing a normal indentation size effect. Using
the relationship between indentation hardness and indentation
depth from strain gradient plasticity theory we curve fitted the
experimental data and found that both the indentation hardness at
the limit of infinite depth and the characteristic length were
dependent on the electric current density. Finite element analysis was per-
formed to analyze the indentation deformation of a two-dimensional tin strip
under the simultaneous action of an electric current. The
simulation results showed that the contact modulus of tin decreased linearly
with the square of the electric current density, qualitatively
in accordance with experimental observations for an electric current density
6 2803.7 A cm2
.
2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: Nanoindentation; Elastic behavior; Hardness |
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