rapid solidification;  Al-Cr alloy;  competing nuclei;  phase selection;  Continuous supercooling

The nucleation dynamics and microstructure of Al-(1~5)Cr (mass fraction) fast-setting alloy were calculated and studied by continuous cooling, and the relationship between the nucleation gestation period and the cooling rate under different components and different cooling rates was obtained, and the phase selection law in the solidification process was obtained, that is, the preferential precipitation of a certain phase was caused by its nucleation kinetic conditions being more advantageous than other phases. Specific to Al-Cr alloys, with the increase of solute content, the critical cold rate required to inhibit the first nucleation of intermetallic phase increases, that is, the tissue of completely supersaturated single-phase α-Al can only be formed in a large cold rate or a very thin band, and the calculation results are in good agreement with experimental detection.