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Observations of Low Cycle Fatigue of Al Thin Films for Mems Applications

Published online by Cambridge University Press:  10 February 2011

G. Cornella
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-2205
R.P. Vinci
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-2205
R. Suryanarayanan Iyer
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-2205
R.H. Dauskardt
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-2205
J.C. Bravman
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-2205
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Abstract

This paper addresses tension-tension (R=0) low cycle fatigue behavior of thin film Al structures released from a substrate. Al beam specimens 2 µm thick, 50 µm wide and 500 µm long (gauge length) were micromachined over a window in a Si substrate. Cyclic load-displacement behavior was investigated using a multiple step test method, in which each specimen was cycled with several blocks of constant maximum displacement amplitude. Load, displacement and temperature were recorded continuously. A load drop and a corresponding stabilized state were observed for each displacement block. Monotonic tension tests to failure were also performed for comparison. Evidence of cyclic creep was observed. SEM images revealed fatigue markings on cyclically loaded specimens but not on monotonically loaded beams.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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