Quantitative analysis of columnar-to-equiaxed transition in Mg-Gd-Zn alloys

• The study provides quantitative insights into the columnar-to-equiaxed transition (CET) in Mg-Gd-Zn alloys, showing that grain size, dendrite tip radius, and secondary dendrite arm spacing decrease exponentially with increasing cooling rate. • The CET is promoted by lower temperature gradients and higher cooling rates, which is crucial for controlling solidification microstructures in industrial casting processes. • The experimental results align with established models (Hunt, Bouchard-Kirkaldy, and GTK), validating the use of phase-field simulations for predicting dendrite morphology and CET. • Increasing critical nucleation supercooling inhibits equiaxed crystal formation, while higher nucleation density promotes CET, offering strategies to tailor alloy microstructures for improved mechanical properties.