A comparative study on precipitation behavior of a sand-cast Al-Li-Cu alloy with the different quenching rates

The performance of large-size structural components with varied wall thickness is mainly determined by the quench sensitivity, while there was a blank of the studies on the quench sensitivity of cast Al-Li alloys. In this study, the precipitation behavior of sand-cast Al-2Li-2Cu-0.5Mg-0.15Sc-0.15Zr-0.05Ti alloy subjected to different quenching conditions in room temperature water, boiling water and air was compared. The effect of the quenching rates on the formation mechanisms of delta' (Al3Li) and T-1 (Al2CuLi) precipitates was discussed. It was found that a rapid quenching rate facilitated the precipitation of T-1 phases and the refinement of delta' phases, which contributes to the improvement of the mechanical properties. During the subsequent ageing, the strength and ductility were enhanced with the quenching rate increasing, but the strength did not vary by more than 15%, indicating that the sand-cast Al-Li-Cu alloy owns a lower quench sensitivity. This work is expected to enlighten the understanding of the evolution mechanisms of precipitates during quenching and provide a reference for the heat treatment of complex structural components for cast Al-Li alloys.

Automated summary

This study compared the precipitation behavior of sand-cast Al-Li alloy under different quenching conditions and discussed the effect of quenching rates on the formation mechanisms of precipitates. It was found that rapid quenching facilitated the precipitation and refinement of precipitates, leading to improved mechanical properties. Furthermore, the alloy was found to have a lower quench sensitivity.