Study of the domains of Portevin-Le Chatelier plastic instabilities in the aluminium-magnesium alloy AG3

Plastic instabilities associated with the Portevin-Le Chatelier (PLC) effect, were studied in an aluminium-magnesium alloy AG3, in large ranges of temperature as well as of strain and stress rates. Experimental results presented in a log sigma - 1/T or log epsilon - 1/T diagram, show that the region of PLC effect is closed at high loading rates. The critical strain at which the PLC phenomenon appears, increases when the loading rate increases at low temperature or at high loading rates. The ''inverse'' behaviour branches are observed at high temperature and at low loading rates.