Ageing characteristics of Al-2.5% Li rapidly solidified alloy

Abstract

The present work was performed on an Al−2.5 wt% Li alloy produced by melt spinning. The ribbons were aged in the temperature range 180 to 310° C for times between 1 min and 120h. The kinetics of coarsening of σ′(Al₃Li) and σ (AlLi) phase particles were investigated using transmission electron microscopy and hardness measurements. The results show that coarsening of σ′(Al₃Li) follows a simple linear relation with the cube root of Me, whereas coarsening of σ(AlLi) does not follow the same trend. We believe that the σ(AlLi) phase nucleates at the σ′(Al₃Li)/matrix interface and grows by the dissolution of the nearby σ′(Al₃Li) particles. The mechanical properties of the powder metallurgy alloy show that a large volume fraction of PFZ contributes to the alloy ductility, ∼ 11 %, in the aged condition. Also, the yield strength is greatly improved due to refinement effects enhanced by rapid solidification.