Microstructure and mechanical properties of Al-Mg-Li-Sc-Zr alloy processed by spray deposition and thermo-mechanical processes

Al-Mg-Li-Sc-Zr alloy was prepared by spray deposition followed by extrusion and heat treatment processes. The effects of aging temperature on microstructure, phase transformation, and mechanical properties of the alloy were studied. The results show that the extruded alloy presents a typical fibrous structure with large amounts of secondary phases distributed along the extrusion direction. After solution and aging treatments, recrystallized structures are founded in the alloy, and the proportion of large size grains increases with the aging temperature increasing. TEM observation shows that the δ′(Al3Li) phase particles are homogeneously distributed in the Al matrix, leading to a significant enhancement of tensile strength. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the alloy after aging at 120 °C for 20 h reach 492.3 ± 9 MPa, 568.2 ± 6 MPa, and 5.8% ± 0.25, respectively. When the aging temperature rises from 120 to 160 °C，the dispersed δ′phases are coarsened gradually and the continuous striped S1(Al2MgLi) phases are observed at the grain boundaries, which causes the declination of strength and elongation of the alloy. •Spray deposition of Al-5.5 Mg-2Li alloy with trace amount of Zr and Sc.•Comprehensive hardness testing to study the aging response.•Relationship between aging condition, microstructure, and mechanical properties.