Role of Impurities and PSBs on Microcracking of Polycrystalline Copper at Very High Numbers of Cycles

Abstract:

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Fatigue cracks in polycrystalline copper may originate from PSBs or grain boundaries. They usually form at the specimen surfaces, but also internal small stage I (shear) cracks have been observed with the ECC/SEM technique. They are formed together with a strongly elongated dislocation cell structure, which is reflecting in many cases localized deformation in “slip lamellae” with eventual ladder-like features, being typical of PSBs. Both, PSBs and small non-propagating cracks are initiated at cyclic stress/plastic strain amplitudes below the conventionally reported PSB threshold values, if the number of cycles exceeds a minimum, e.g. approximately 5x108 in the VHCF range. The internal small cracks are formed not only in polycrystalline electrolytic copper of 99.98% purity but also in high purity (99.999%) material.

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Periodical:

Edited by:

Pavel Šandera

Pages:

29-34

DOI:

10.4028/www.scientific.net/KEM.465.29

Citation:

S. Stanzl-Tschegg et al., "Role of Impurities and PSBs on Microcracking of Polycrystalline Copper at Very High Numbers of Cycles", Key Engineering Materials, Vol. 465, pp. 29-34, 2011

Online since:

January 2011

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$35.00

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