Microstructural characteristics and mechanical properties of Al–2.5 wt.% Li–1.2 wt.% Cu– xMg alloys

Abstract

Microhardness of heat-treated Al–2.5 wt.% Li–1.2 wt.% Cu–0.12 wt.% 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.