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Onset of the Portevin-Le Chatelier effect: role of synchronization of dislocations

Abstract : The problem of the onset of the Portevin-Le Chatelier (PLC) effect is revised by combining a study of the kinetics of the flow stress evolution upon abrupt changes in the applied strain rate and acoustic emission (AE) accompanying plastic deformation of an AlMg alloy. The kinetic measurements allow evaluating the strain-rate sensitivity of the flow stress and the time characteristics of transient processes as functions of plastic strain. Using known criteria of plastic instability, domains of instability are constructed in the (strain, strain rate) plane. A particular accent is put on the strain-rate range corresponding to the so-called “inverse” behavior. The comparison of such maps with experimental data on the critical strain testifies to the insufficiency of these criteria for explaining the onset of the PLC effect. Moreover, the slow transient kinetics contradicts observations of the fast development of stress drops. The AE measurements bear witness that the stress serrations are associated with bursts in duration of acoustic events generated by the collective motion of dislocations. The possible role of synchronization of dislocation dynamics on the onset of plastic instability is discussed.
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Submitted on : Thursday, May 4, 2017 - 1:43:56 PM
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  • HAL Id : hal-01518210, version 1


Tatiana Lebedkina, Nikolay P. Skobelev, Mikhail Lebyodkin. Onset of the Portevin-Le Chatelier effect: role of synchronization of dislocations. THERMEC 2013: International Conference on Processing & Manufacturing of Advanced Materials, Dec 2013, Las Vegas (NV), United States. pp.198-203. ⟨hal-01518210⟩



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