LAUSR

Abstract La and Ce elements, as additives to aluminum alloys, have significant effects on removing harmful impurities (Fe, Si) and improving electrical conductivity. In the present work, the difference in electrical conductivity by the addition of La and Ce elements was revealed. The results showed that the conductivity of as-cast Al–Ce alloy was higher than that of as-cast Al–La alloy at the same addition content, but their electrical conductivity was the same after heat treatment at 300 °C for 24 h. Firstly, Ce element has a stronger purification of Fe and Si impurities in the aluminum matrix, resulting in the formation of Al–Fe–Si–Ce compounds rather than solid solution in the aluminum matrix. However, the purification capability of La element is a little weaker than that of Ce element, which is prone to form more solid solution atoms in the aluminum matrix. Secondly, the second phase of as-cast Al–La alloy is distributed continuously at grain boundaries, where the amount of the precipitation increases with the increase of addition of La. The second phase of as-cast Al–Ce alloy is distributed in the form of particles and short rods in the matrix when the amount of added Ce is low. While, the second phase concentrated at the grain boundaries when the amount of added Ce is high. The above two points are the main reason why the conductivity of as-cast Al–Ce alloy was higher than that of as-cast Al–La alloys. After heat treatment at 300 °C for 24 h, for Al–La and Al–Ce alloy, most of the solid solution atoms completely precipitated from the aluminum matrix and their micromorphology is similar. There is the main reason why they have the same conductivity.