Tschegg, S., Eichinger, K., Weidner, A., Tschegg, E., Bernardi, J., & Schönbauer, B. (2011). Role of Impurities and PSBs on Microcracking of Polycrystalline Copper at Very High Numbers of Cycles. In Materials Structure & Micromechanics of Fracture IV (pp. 29–34). Trans Tech Publications. https://doi.org/10.4028/www.scientific.net/KEM.465.29
6th international conference “Materials Structure & Micromechanics of Fracture (MSMF-6)"
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Event date:
28-Jun-2010 - 30-Jun-2010
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Event place:
Brno
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Event place:
SK
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Number of Pages:
6
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Publisher:
Trans Tech Publications
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Publisher:
CH-8712 Stafa-Zurieh
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Publisher:
Trans Tech Publications Ltd
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Keywords:
Internal cracks; stage I (shear) cracks; small cracks; persistent slip bands (PSBs); crack nucleation; very high cycle fatigue (VHCF); ECC/SEM; polycrystalline copper
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Abstract:
. 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.
