Scaling in the Local Strain-Rate Field during Jerky Flow in an Al-3%Mg Alloy

Mikhail Lebyodkin (1) , Youcef Bougherira (2) , Tatiana Lebedkina (1, 3) , Denis Entemeyer (1)

1 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
2 UROP - Unité de recherche en optique et photonique
3 Labex DAMAS

Jerky flow in alloys, or the Portevin-Le Chatelier effect, presents an outstanding example of self-organization phenomena in plasticity. Recent acoustic emission investigations revealed that its microscopic dynamics is governed by scale invariance manifested as power-law statistics of intermittent events. As the macroscopic stress serrations show both scale invariance and characteristic scales, the micro-macro transition is an intricate question requiring an assessment of intermediate behaviors. The first attempt of such an investigation is undertaken in the present paper by virtue of a one-dimensional (1D) local extensometry technique and statistical analysis of time series. The data obtained complete the missing link and bear evidence to a coexistence of characteristic large events and power laws for smaller events. The scale separation is interpreted in terms of the phenomena of self-organized criticality and synchronization in complex systems. Furthermore, it is found that both the stress serrations and local strain-rate bursts agree with the so-called fluctuation scaling related to general mathematical laws and unifying various specific mechanisms proposed to explain scale invariance in diverse systems. Prospects of further investigations including the duality manifested by a wavy spatial organization of the local bursts of plastic deformation are discussed.

Mots clés: Portevin-Le Chatelier effect; aluminum alloys; local extensometry; avalanches; self-organized criticality; synchronization; fluctuation scaling

Domaines: Mécanique des matériaux [physics.class-ph]

Mikhail Lebyodkin, Youcef Bougherira, Tatiana Lebedkina, Denis Entemeyer. Scaling in the Local Strain-Rate Field during Jerky Flow in an Al-3%Mg Alloy. Metals, 2020, 10 (1), pp.134. ⟨10.3390/met10010134⟩. ⟨hal-02443355⟩