<p>Two lanthanum microalloyed Al-Si alloys were subjected to single-pass and double-pass intermittent uniaxial hot compression tests at temperatures of 300&#xa0;°C and 400&#xa0;°C and strain rates of 0.1&#xa0;s⁻¹ and 1&#xa0;s⁻¹ to investigate the thermal deformation behavior and correspond microstructural changes of Al-Si alloys with different La additions. The findings suggest that the Al₁₁La₃ phase, characterized by a body-centered orthorhombic arrangement, is formed in the alloy with a 0.068% La addition. This structure is capable of pinning dislocations during hot deformation. Concurrently, La can facilitate the formation of stacking faults and twins in eutectic Si particles by refining and spheroidizing them. These tiny particles can impede dynamic recovery and dynamic recrystallization during hot deformation, increasing peak flow stress and storing a greater quantity of deformation energy during the deformation process. The stored deformation energy drives static recovery and recrystallization in the holding stage between passes.</p>