Research on a Novel Mg-8li-3al-1sn Thin Sheet with Excellent Mechanical Stability

Abstract

The Mg-8Li-3Al-1Sn (LAT831) alloy sheets were fabricated through extrusion and on-line warm rolling. The microstructure and mechanical properties of the LAT831 alloy sheets were systematically investigated using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. Additionally, the mechanical stability of the sheet was evaluated at 100 °C for 72 hours. The results indicate that LAT831 alloy sheets are composed of β-Li, α-Mg, MgLiAl2, Mg2Sn, and Li2MgSn. Dynamic recrystallization and dynamic precipitation occur during hot extrusion, leading to grain refinement. The grain sizes of the α-Mg and β-Li phases in the extruded alloy are ~ 2.4 μm and ~ 7.7 μm. The as-extruded LAT831 alloy sheet exhibits an ultimate tensile strength (UTS) of 226 MPa, a yield strength (YS) of 185 MPa, and an elongation (EL) of 21.6% respectively. The as-rolled LAT831 alloy sheet achieves a UTS of 270 MPa, a YS of 233 MPa, and an EL of 12.3%. After undergoing mechanical stability testing at 100 °C for 72 hours, the alloy sheet exhibits a UTS of 275 MPa, a YS of 234 MPa, and an EL of 7.6%, demonstrating excellent mechanical stability.

Keywords: Mg-Li alloy, dynamic precipitation, microstructure, mechanical stability, mechanical properties