Burst Acoustic Emission During the Bauschinger Effect in F.C.C. and H.C.P. Metals and Alloys

TLDR: In this article, the Bauschinger effect in polycrystalline 99.99% Al, 6061 and 2024A1 alloys, Cu-7.9% Al alloy, 70-30 brass and 99.95% Mg was studied for the first time at ultrasonic frequencies using acoustic emission.

Abstract: Unload burst type acoustic emission during the tension cycle of the stress-strain hysteresis loop during cyclic deformation was studied and related to grain size, Bauschinger strain and stacking fault energy. The Bauschinger effect in polycrystalline 99.99% Al, 6061 and 2024A1 alloys, Cu-7.9% Al alloy, 70-30 brass and 99.95% Mg was studied for the first time at ultrasonic frequencies using acoustic emission. The relationships observed lead to a natural identification of acoustic emission the ultrasonic frequency range during cyclic deformation with the very low frequency strain burst phenomenon of Neumann. We utilize Neumann's edge dipole dissociation-trapping avalanch (EDDTA) theory for the cyclic deformation strain burst phenomenon to explain the burst acoustic emission during the Bauschinger effect reported here. A possible extension of this correspondence to non-cyclic deformation acoustic emission and its possible relation to the monatonic, non-cycle torsion millimicroplastic strain burst phenomenon of Tinder and Trzil is briefly considered.