Acoustic emission during stress relaxation of pure magnesium and AZ magnesium alloys

Abstract

Acoustic emission (AE) was monitored and analysed during tensile tests of pure Mg and Mg alloys of AZ series in order to study the influence of the alloy composition on plastic deformation. The Kaiser effect was used to determine the stability of microstructure. During the tests at room temperature, repeated stress relaxations were performed. The solute-dislocation interaction in the alloys leads to ageing phenomenons, which are manifested as the post-relaxation effect and subsequent serrated flow (Portevin-Le Chatelier effect). The post-relaxation effect was sensitive to the alloy composition and to the strain, at which the stress relaxation was performed.

Investigating a twinning–detwinning process in wrought Mg alloys by the acoustic emission technique

“…2a and 3a), suggesting the beginning of dislocation slip before yielding. This was also observed in previous works [29,30]. The twin nucleation was found as the main deformation mechanism at the macroscopic yield, and it significantly influences the yield stress.…”

General framework for acoustic emission during plastic deformation

“…The approach can also be applied to other types of plastic deformations not considered here. For example, the AE technique has been used to study variety of modes of plastic deformation such as load-rate controlled PLC experiments [57], cyclic loading experiments [58] and stress relaxation experiments [22]. Our method is applicable to these cases since the dislocation evolution equations can be coupled to load-rate controlled and cyclic loading conditions instead of the constant strain rate deformation [59].…”

Effect of the loading mode on the evolution of the deformation mechanisms in randomly textured magnesium polycrystals – Comparison of experimental and modeling results

“…In materials science, this approach can be successfully applied for general characterization, when the main goal is the investigation of the influence of the experimental and material parameters on the deformation behavior (e.g. (Dobroň et al, 2007;Chmelik et al, 2007)). Nevertheless, the hitbased AE recording has several drawbacks: (i) in most cases, there is no direct link between the source mechanism and the AE parameters; (ii) the proper setting of the signal extracting parameters is rather difficult, when multiple, strong sources are simultaneously active.…”