Microstructural characteristics and mechanical properties of Al-2.5 wt. percent Li-1.2 wt. percent Cu-xMg alloys

摘要

Microhardness of heat-treated Al-2.5 wt. percent Li-1.2 wt. percent Cu-0.12 wt. percent Zr-xMg alloys was observed to increase with increasing Mg content mainly due to increased solid solution strengthening, reduced grain size and increased amount of fine quasi-crystalline Al_6Cu(Li, Mg)_3 precipitates. Although coarse quasi-crystalline Al_6Cu(Li, Mg)_3 phases were found in all investigated alloys, the quasi-crystalline phase as a fine precipitate could be only observed in the alloys containing high Mg contents. The tensile strength was significantly increased in the alloys with high Mg contents after a heat treatment, owing to the enhanced precipitations of fine Al_3Li and Al_3Zr phases.