Archives of Acoustics, 32, 4(S), pp. 87-93, 2007

Acoustic emission in compressed Mg-Li and Al alloys processed by ECAP, HPT and ARB methods

Andrzej Pawełek
Aleksander Krupkowski Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków
Poland

Andrzej Piątkowski
Aleksander Krupkowski Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków
Poland

Jan Kuśnierz
Aleksander Krupkowski Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków
Poland

Joanna Bogucka
Aleksander Krupkowski Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków
Poland

Zdzisław Jasieński
Aleksander Krupkowski Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków
Poland

Zbigniew Ranachowski
Institute of Fundamental Technological Research, Department of Physical Acoustics, Polish Academy of Sciences, Świętokrzyska 21, 00-049 Warszawa
Poland

Przemysław Ranachowski
Institute of Fundamental Technological Research, Department of Physical Acoustics, Polish Academy of Sciences, Świętokrzyska 21, 00-049 Warszawa
Poland

Jarosław Mizera
Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 14, 02-507 Warszawa
Poland

Stanislav Kúdela
Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Raˇcianska 75, 831 02 Bratislava
Slovakia

Stanislaw Kúdela Jr.
Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Raˇcianska 75, 831 02 Bratislava
Slovakia

In the paper there are presented the results of investigations of the relations between acoustic
emission (AE) and the plastic strain mechanisms during channel-die compression of materials,
based on both Mg-Li and Al alloys, having ultra fine-grained (UFG) or nanocrystalline
structure obtained using the technique of equal channel (of both quadratic and circular section)
angular pressing (ECAP) as well as the technique of high pressure torsion (HPT). Also
the AE in compression and tensile tests of UFG (nanocrystalline) Al alloys obtained by accumulative
roll-bonding (ARB) method have been investigated. The results obtained using a
new generation AE analyzer are compared with those obtained for similar materials but not
subjected to ECAP, HPT and ARB processing. Moreover, the wavelet analysis of the detected
AE signals based on the acoustic maps (acoustograms) and spectral characteristics has been
carried out and the AE behaviour is discussed in the dislocation aspects of both plastic strain
mechanisms and possible superplastic flow in UFG or nanocrystalline materials.
Keywords: acoustic emission, Mg-Li-Al alloys, compression test, nanocrystalline and/or ultra fine-grained (UFG) structures, strain mechanisms, dislocations, intensive strain methods (ECAP, HPT, ARB).
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