Influence of non-isothermal aging on mechanical properties and microstructures of an Al-Li alloy

Abstract:

The mechanical properties and micro-structures of a Mg, Ag and Zn multi-microalloyed Al-Li alloy with isothermal T8 aging and non-isothermal (cooling) T8 aging were studied. The results showed that the main strengthening precipitates were T1 (Al2CuLi), some ?? (Al2Cu) and ??(Al3Li) precipitates played a supplementary strengthening effect. Compared to the isothermal T8 aging, the cooling T8 aging enhanced the Al-Li alloy strength but did not lower its elongation. In addition, the precipitation and growth of T1 precipitates were slower during cooling T8 aging process due to its lowered temperature. Meanwhile, the fraction of ?? and ?? precipitates were higher in the alloy with cooling T8 peak aging, which caused a higher supplementary strengthening effect.

Key words:Al-Li alloy; Mechanical property; Micro-structure; Isothermal T8 aging; Non-isothermal T8 aging