Anomalous hardening of Al-8%Ca eutectic alloy due to a non-equilibrium phase state transition under laser irradiation

•As-cast Al-8%Ca eutectic aluminum alloy was processed by laser irradiation.•Laser irradiation leads to a 4-fold increase in the microhardness of the alloy.•The hardened state has increased thermal stability.•A supersaturated solid solution of calcium in aluminum is formed.•Numerous dislocation loops are formed. The relationship between the change in the structure and the hardening effect of an Al-8%Ca eutectic aluminum alloy under laser irradiation was studied. Laser surface processing of the as-cast alloy was carried out at a laser power of 370 W and a beam velocity of 750 mm/s. It is shown that laser irradiation leads to a 4-fold increase in the microhardness of the alloy (up to 3.6 GPa) due to the creation of a supersaturated solid solution of calcium in aluminum and a multiple increase in the dislocation density.