Abstract: The diffusion coefficients of lanthnum in liquid Al-Si alloy have been measured successfully by the anodic chronopotentiometry. At 973K, the diffusion coefficient of lanthanum (D_(La(Al-Si))) in liquid Al-5.2wt-%Si alloy equals (0.91±0.01)×10~(-5) cm~2 s~(-1) . In the range of temperatures 953-1053K, the relationship between the diffusion coefficient and the tem- perature is represented by 1gD_(La(Al-Si))=-1.78×10~(-3)-4909/T. The activation energy is Q=94.00kJ·mol~(-1). Using the diffusion data of lanthanum and strontium, the effect of the diffusion of the modifier on the incubation period of modification and cooling rate has been discussed.

Key words: diffusion coefficient, activation energy, lanthanum, Al-+Si alloy