Effect of Nd on the microstructure, mechanical properties, and corrosion of Mg-11 Li-3Al-2Zn-0.2Zr alloy

The effect of Nd on the microstructure, mechanical properties and corrosion of homogenized Mg-11Li-3Al-2Zn-0.2Zr alloy was studied. The cast ingots were fabricated in a vacuum induction furnace. The as-cast Mg-11Li-3Al-2Zn-xNd-0.2Zr (x=0, 0.5, 1.0, 1.5) alloy was homogenized at 280 ℃ for 24 h. XRD and SEM were used to analyze the microstructure of the alloy, and the tensile test and fracture analysis were carried out. The corrosion of alloy in 3.5% NaCl solution was studied by electrochemical method and hydrogen evolution test. The results show that Mg-11Li-3Al-2Zn-0.2Zr alloy mainly consists of β-Li, AlLi, and MgLi₂Al phases. The addition of Nd results in the formation of NdAl3 phase. With the increase of Nd content, the strength and plasticity of the alloy increase first and then decrease. Mg-11Li-3Al-2Zn-1Nd-0.2Zr alloy shows the best mechanical properties, whose tensile strength and elongation increase by 28.8 % and 51.3 % respectively compared with Mg-11Li-3Al-2Zn-0.2Zr alloy. The addition of Nd improves the corrosion resistance of the alloy. Mg-11Li-3Al-2Zn-0.5Nd-0.2Zr alloy, with a more positive corrosion potential and a lower hydrogen evolution rate, shows the best corrosion resistance.