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

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Authors

  • 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

Abstract

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).