The electric current-induced suppression of the Portevin – Le Chatelier effect in Al–Mg alloys

Abstract

The direct current-induced suppression of the Portevin – Le Chatelier (PLC) effect has been revealed and investigated in Al–5wt% Mg and Al–6wt% Mg alloys during tensile tests at a constant strain rate. Suppression of the PLC effect by direct electric current manifests itself as an increase in the critical strain εc for the onset of serration flow with increasing current density exceeding a certain critical value jc which depends on the weight content of Mg in Al–Mg alloy. The current density range in which the transition from a jerky tensile curve to a smooth one occurs is found to depend on the type of PLC instabilities apart from the testing temperature and an imposed strain rate. The obtained results show that the observed suppression of jerky flow by electric current is not directly associated with Joule heating per se of the whole sample. Possible mechanisms of the phenomenon are discussed.