Influence of Rare Earths Addition on the Properties of Al-Li Alloys

Aluminum alloys are considered one of the best choices as structural material for aerospace applications, guaranteeing lightweight and strength at the same time. In this work Al-Li alloys with 6% (wt %) of Li are used. To increase further the strength of the material, new alloys are produced by adding different quantities (0.01, 0.05, 0.1, and 0.5 wt %) of rare earths (Nd, Y, Ce, Pr). The microstructure of the samples is examined using scanning electron microscope (SEM). The improvement of the mechanical properties is measured by means of Vickers hardness tests. Also the corrosion resistance of the alloys is evaluated with open circuit voltage (OCV) measurements. At the same time, the thermophysical properties are measured as well, at various temperatures, from 80 to 500 degrees C. The results show that an increase in the Rare Earth (RE) content causes an increase in the mechanical properties and a reduction in the thermal conductivity. Regarding the corrosion resistance, a maximum in the corrosion properties can be found for 0.05% of RE.