Microstructure and mechanical properties of a 2091 AlLi alloy—III. Quantitative analysis of portevin le chatelier instabilities and relation to toughness in AlLi, AlCuMg and AlLiCuMg (2091) alloys

The microstructure and mechanical properties of a 2091 alloy are studied and compared to simpler AlLi and CuMg alloys. For ageing times between 6 and 24 h at 150°C, the 2091 alloy exhibits a toughness drop and a simultaneous change in PLC characteristics (as evidenced by a combination of local and total strain measurements), but no significant change in microstructure, except for the size of δ′ precipitation. SEM in situ tests show that …