Archives of Acoustics, 31, 4(S), pp. 75-81, 2006

Anisotropy of acoustic emission and Portevin– Le Châtelier phenomena in polycrystalline aluminium alloys subjected to tensile tests

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

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

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

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

In the present work the acoustic emission (AE) method has been used in the plastic instability
investigations related to the Portevin–Le Châtelier phenomenon (PL effect, nonhomogeneous
strain, jerky flow) occurring in polycrystalline aluminium alloys subjected to
tensile tests at ambient temperature. There have been observed very essential correlations
between AE and PL phenomena and a strong anisotropy of both these effects in samples
cut at various angles with respect to the initial rolling direction has been found. The results
of AE measurements were obtained using a new AE analyser and, for a few samples, they
have been compared with those obtained applying an analyser of older generation, used till
now. Moreover, the new software allowed additionally to carry out the analysis of single AE
events, which, in turn, created better possibility to determine the relations between the nonhomogeneous
strain mechanisms of the PL type and the mechanisms of AE events generation.
The results are discussed also in the context of the existing models of the PL effect and the
theoretical concepts of AE sources.
Keywords: acoustic emission (AE), non-homogeneous strain, Portevin–Le Châtelier phenomenon (PL effect), jerky flow, tensile test, aluminium alloys, dislocations.
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