The Effect of Gd Concentration on the Mechanical Properties and Corrosion Behavior of Extruded Mg-8Li-3Al- x Gd ( x = 0, 0.6, 1.2, and 1.8 wt.%) Alloys

The mechanical properties and corrosion resistance of extruded Mg-8Li-3Al alloys with varying Gd contents are investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical tests. The results show that the size of α-Mg grains in extruded Mg-8Li-3Al alloys is obviously refined during the dynamic recrystallization process due to the addition of Gd. The ultimate tensile strength of extruded Mg-8Li-3Al-1.2Gd alloy attains to 278 MPa, which is approximately 35% higher than that of the matrix alloy (206 MPa). The improved mechanical properties of the Mg-8Li-3Al alloys containing Gd are mainly attributed to the formation of the Al 2 Gd phase, which can refine the α-Mg grain as a heterogeneous nucleation substrate and hinder the movement of the dislocations and grain boundaries and the rotation of the grains. The comprehensive electrochemical results show that the corrosion resistance of extruded Mg-8Li-3Al- x Gd ( x = 0.6, 1.2 and 1.8 wt.%) alloys is improved by the addition of Gd. In addition, the corrosion mechanism of extruded Mg-8Li-3Al alloys contained Gd is discussed.